effectiveness of Wildlife Corridors: Literature Review
The science of creating wildlife corridors is relatively new. As a result, it’s important to evaluate projects based on metrics that demonstrate success. Equally important is understanding opportunities for improvement. We have compiled relevant studies from peer-reviewed and grey-literature to develop these insights and highlight important considerations in creating wildlife corridors.
| Topic | Paper | Abstract | Link To Paper |
|---|---|---|---|
| Species Movement and Dispersal, Plant Dispersal, Ecosystem Services | A. Chovanec et. al. Constructed inshore zones as river corridors through urban areas. The Danube in Vienna: preliminary results | Over the last 125 years, river regulation has considerably changed the ecological conditions of the Austrian Danube and its floodplains such that the system is now very fragmented. Within the municipal area of Vienna, these changes have been particularly severe: river embankments and a bypass channel (the "New Danube"), separated from the main river by an artificial island ("Danube Island"), are the key elements of flood control, and river levels are controlled by the Vienna hydroelectric power plant (Freudenau). During construction of the hydroelectric power plant, the previously straight shoreline of the 21-km long Danube island, with its steep embankments, was restructured by creating shallow water areas, gravel banks, small permanent backwaters and temporary waters. This paper describes the scheme and the results from the first year of a 4-year monitoring programme ("Danube Island Monitoring Programme" DIMP) investigating the colonization and successional processes of these areas by monitoring relevant indicator groups (vegetation, dragonflies, amphibians, reptiles, waterfowl). | View Paper |
| Species Movement and Dispersal | A. Saunders and R. J. Hobbs, editors. Nature conservation 2: the role of corridors. | Publishes the proceedings of a conference held in Western Australia in 1989, and presents recent information on landscape corridor function, including practical advice on issues relating to corridor function management. The layout follows that of the conference with 38 chapters divided into four sections: inventory and assessment of corridors; values of corridors; movement of biota; and management, establishment, maintenance and rehabilitation. Each section is introduced by a theoretical review followed by up to six contributed papers, these covering work on all aspects of landscape corridors, mainly in Australia, but also in Belgium, Canada, New Zealand, South Africa and the US. The penultimate chapter contains summaries of most of the workshop discussions held, and the final chapter comprises the editors' views on the outcome of the conference and where research and management should be directed in the future. The majority of papers are abstracted separately. The principal findings of the conference are published separately in a 21-page booklet (ISBN 0 949324 38 8), in a form designed for use by land managers in the management of linear remnants for nature conservation. | View Paper |
| Benefits and Consequences For Local Communities | A.P. Clevenger, A. T. Ford & M. A. Sawaya Banff Wildlife Crossings Project: Integrating Science and Education in Restoring Population Connectivity Across Transportation Corridors. | The Banff Wildlife Crossings Project's (BWCP's) monitoring and wildlife research, coupled with outreach and education, aims to properly inform the transportation community and wildlife managers of the environmental and societal benefits of Banff's highway infrastructure investments. In addition, the Project seeks to share its findings on wildlife crossing design elements, requirements and their effectiveness. The BWCP goal is to increase transportation and wildlife agency understanding and community awareness so that other busy roads in the mountain parks and other locales in the Canadian Rocky Mountains and the United States benefit from the findings of the BWCP. This will allow other communities to develop sustainable transportation practices that provide ecological connectivity for wildlife across their transportation corridors as well as maintain motorist safety. | View Paper |
| Genetic Variation | Aars, J. and Rolf, A. The effect of habitat corridors on rates of transfer and interbreeding between vole demes. Ecology Vol. 80, No. 5 (Jul., 1999), pp. 1648-1655 (8 pages) Published By: Wiley | It has been proposed that habitat corridors enhance exchange of individuals (transfer) and interbreeding between otherwise isolated demes in fragmented populations. However, due to the paucity of experimental studies this proposition has become controversial. We tested these proposed effects of corridors in 12 experimentally fragmented root vole populations. A 50-m long habitat corridor connected two large habitat patches in each of six treatment populations, while equivalent habitat patches in six control populations had no corridor connection. Each of the two patches in each population was initially colonized by founder demes that were monomorphic with respect to two different marker alleles of a single locus. The rate of transfer of individuals and the resultant degree of interbreeding (heterozygosity) between the two demes were monitored by capture-recapture methodology and genetic analyses over the reproductive season. Females were predominantly philopatric in these populations; more than four-fifths of the founder deme females settled and reproduced in their original patch. However, corridors significantly facilitated the transfer of females. The transfer rate of males was generally very high; approximately four-fifths, independent of the experimental factor (absence or presence of corridors). The sex-specific transfer pattern gave rise to very high rates of interbreeding (heterozygosity). The rate of interbreeding was enhanced by the presence of corridors, and more so than expected from the transfer rate. The lack of concordance between expected and observed heterozygosity in the corridor populations was probably due to short-term mating excursions facilitated by the presence of corridors. | View Paper |
| Species Richness | Abson, R. N, & Lawrence, R. E. (2003). Monitoring the use of the Slaty Creek wildlife underpass, Calder Freeway, Black Forest, Macedon, Victoria, Australia. UC Davis: Road Ecology Center. Retrieved from https://escholarship.org/uc/item/6s9970wb | The Slaty Creek Wildlife Underpass was built into the Calder Freeway, Macedon, Victoria, to facilitate safe passage for species between forest block, now affected by this new section of freeway through the Black Forest. A 12-month monitoring regime was established, consisting of 14 monitoring methods to detect a variety of animals. Intensive sampling was conducted for one week per month, within the underpass, and with two control sites on either side of the underpass, along the Slaty Creek. The monitoring sampled for mammals, reptiles, amphibians and birds, encountering a total of 116 species within the Black Forest region, with most of these also being detected within the underpass. | View Paper |
| Benefits and Consequences For Local Communities | Agrawal, Arun & Gibson, Clark. (1999). Enchantment and Disenchantment: The Role of Community in Natural Resource Conservation. World Development. 27. 629-649. 10.1016/S0305-750X(98)00161-2. | The poor conservation outcomes that followed decades of intrusive resource management strategies and planned development have forced policy makers and scholars to reconsider the role of community in resource use and conservation. In a break from previous work on development which considered communities a hindrance to progressive social change, current writings champion the role of community in bringing about decentralization, meaningful participation, and conservation. But despite its recent popularity, the concept of community is rarely defined or carefully examined by those concerned with resource use and management. We seek to redress this omission by investigating “community” in work concerning resource conservation and management. We explore the conceptual origins of the community, and the ways the term has been deployed in writings on resource use. We then analyze those aspects of community most important to advocates for community's role in resource management — community as a small spatial unit, as a homogeneous social structure, and as shared norms — and indicate the weaknesses of these approaches. Finally, we suggest a more political approach: community must be examined in the context of development and conservation by focusing on the multiple interests and actors within communities, on how these actors influence decision-making, and on the internal and external institutions that shape the decision-making process. A focus on institutions rather than “community” is likely to be more fruitful for those interested in community-based na | View Paper |
| Benefits and Consequences For Local Communities | Agrawal, Arun. (2007). Forests, Governance, and Sustainability: Common Property Theory and its Contributions. International Journal of the Commons. 1. 10.18352/ijc.10. | This paper examines the contributions of scholars of commons to forest governance. It outlines the domain of the research on forest-based commons by examining how ownership rights in relation to forests are broadly distributed in different parts of the world. It reviews theoretical and empirical contributions from scholars of forest-based commons by keeping in mind that much of the research on forest-based commons contributes directly to an understanding of policy concerns related to forest governance. Analyzing the contributions of the research on forest-based commons helps identify the importance of property rights arrangements, local levels of use and management, and communal relationships that often frame local governance. The review also assesses gaps related to data, theory, and methods in the study of forest-based commons. The conclusion to the paper outlines some pressing and exciting new areas for future research. | View Paper |
| Genetic Variation | Arens, Paul & van der Sluis, Theo & Westende, Wendy & Vosman, Ben & Vos, Claire & Smulders, Marinus J M. (2007). Genetic population differentiation and connectivity among fragmented Moor frog (Rana arvalis) populations in The Netherlands. Landscape Ecology. 22. 1489-1500. 10.1007/s10980-007-9132-4. | We studied the effects of landscape structure, habitat loss and fragmentation on genetic differentiation of Moor frog populations in two landscapes in The Netherlands (Drenthe and Noord-Brabant). Microsatellite data of eight loci showed small to moderate genetic differentiation among populations in both landscapes (F ST values 0.022 and 0.060, respectively). Both heterozygosity and population differentiation indicate a lower level of gene flow among populations in Noord-Brabant, where populations were further apart and have experienced a higher degree of fragmentation for a longer period of time as compared to populations in Drenthe. A significant isolation-by-distance pattern was found in Drenthe, indicating a limitation in dispersal among populations due to geographic distance. In Noord-Brabant a similar positive correlation was obtained only after the exclusion of a single long-time isolated population. After randomised exclusion of populations a significant additional negative effect of roads was found but not of other landscape elements. These results are discussed in view of improving methodology of assessing the effects of landscape elements on connectivity. | View Paper |
| Species Movement and Dispersal | ARESCO, MATTHEW. (2005). Mitigation measures to reduce highway mortality of turtles and other herpetofauna at a north Florida lake. Journal of Wildlife Management - J WILDLIFE MANAGE. 69. 549-560. 10.2193/0022-541X(2005)069[0549:MMTRHM]2.0.CO;2. | Roads built through or near wetlands cause significant mortality of reptiles and amphibians and create barriers to migration and dispersal. I investigated the number of times turtles and other herpetofauna attempted to cross a 4-lane highway at Lake Jackson, Florida, USA, during a period of severe drought (Feb-Apr 2000). Levels of road mortality were so high that I designed and installed a temporary drift fence system to work with an existing drainage culvert and for the next 2.5 years I evaluated its effectiveness at reducing road mortality and facilitating migration. I monitored roads and fences several times per day for 44 months, during both drought and non-drought conditions. A total of 10,229 reptiles and amphibians of 44 species were found either road killed or alive behind drift fences: 8,842 turtles, 838 frogs, 363 snakes, 152 lizards, 32 alligators, and 2 salamanders. Drift fences combined with intensive monitoring greatly reduced turtle road kills and facilitated the use of an under-highway culvert. Along a 0.7-km section of the highway, turtle mortality before installation of the fence (11.9/km/day) was significantly greater than post-fence mortality (0.09/km/day) and only 84 of 8,475 turtles climbed or penetrated the drift fences. Pre-fence data provided strong evidence that turtles cannot successfully cross all 4 lanes of U.S. Highway 27, as 95% of 343 turtles were killed as they first entered the highway adjacent to the shoulder and the remaining 5% were killed in the first two traffic lanes. According to a probability model, the likelihood of a turtle successfully crossing U.S. Highway 27 decreased from 32% in 1977 to only 2% in 2001 due to a 162% increase in traffic volume. Therefore, at least 98% of turtles diverted by the fences probably would have been killed if fences were not in place. The results of this study represent the highest attempted road-crossing rate ever published for turtles (1,263/km/year). Because of demographic and life history constraints, turtle populations may incur irreversible declines in areas where road mortality is high, especially when mass migrations are triggered by periods of drought. | View Paper |
| Species Richness | Arizona Department of Transportation Research Center Evaluation of Desert Bighorn Sheep Overpass Effectiveness: U.S. Route 93 Long-Term Monitoring | During the planning stage of upgrading U.S. Route (U.S.) 93 from a two-lane highway to a four-lane divided highway, there were concerns for the local desert bighorn sheep (DBS) population. Vehicle collisions with DBS were estimated at 11 per year prior to reconstruction and would likely increase after reconstruction. To overcome collision concerns, the Arizona Department of Transportation (ADOT) integrated three overpass (OP) structures—two 50 feet wide and one 100 feet wide. They are Arizona’s first wildlife OPs and North America’s first OPs for DBS. These OPs, along with three culverts and the dry washes under two bridges, were linked with fencing to limit DBS access to U.S. 93 and guide DBS to the safe crossings. From March 2011 through March 2015, researchers evaluated the success of these mitigation measures with video and still cameras, Global Positioning System collars on DBS, and DBS-vehicle collision monitoring. DBS used the OPs (5862 crossings) more than the dry washes under the bridges (474 crossings) and more than the culverts (195 crossings). Passage rate (crossings/approaches) at the OPs increased by 210 percent from years one to four of the study. Collared DBS crossings and passage rates increased by 100 percent and 1367 percent, respectively, from years one to four. DBS shifted their distribution of crossings more evenly across the study area and crossings became focused at crossing structures. Vehicular collisions with DBS were reduced by 68 percent in the first two years of monitoring until ADOT maintenance personnel addressed DBS breach points, after which only one vehicle-killed DBS was documented during 2011-2015, accounting for an 86 percent reduction overall and a 97 percent reduction in the years following repair of the fence breaches. These findings indicate that appropriately located 50-foot-wide overpasses connected with 7- to 8- foot ungulate-proof fencing, along with animal escape ramps, can reduce DBS-vehicle collisions and promote habitat connectivity. Post-construction monitoring can document effectiveness of mitigation measures and quickly identify areas of DBS access for modification or maintenance, to ensure long-term success of the measures. | View Paper |
| Ecosystem Services, Benefits and Consequences For Local Communities | Aryal, Achyut & Brunton, Dianne & Shrestha, Tej Kumar & Koirala, Raj & Lord, Jennifer & Thapa, Y.am & Adhikari, Bikash & Ji, Weihong & Raubenheimer, David. (2012). Biological Diversity and Management Regimes of the Northern Barandabhar Forest Corridor: An Essential Habitat for Ecological Connectivity in Nepal. Tropical Conservation Science. 5. 38-49. 10.1177/194008291200500105. | Despite the development of progressive policies in forestry and wildlife management sectors in Nepal, over the last ten years it has become clear that protected areas in the country lack the landscape connectivity required to support viable populations of endangered species such as rhino (Rhinoceros unicornis) and tiger (Panthera tigris tigris). Forest resources that provide essential habitat for a diverse array of species, and forest products to many human populations continue to decline. The present study, focusing upon the northern Barandabhar Forest Corridor (BFC) aimed to begin to address these problems by establishing preliminary data concerning the extent, biological diversity and resources available for local communities of the forest in order to promote a community-based management strategy. Results established that the northern BFC covers an area of 10,644 ha between the East-West Mahendra highway and the Mahabharat range, incorporating 15 community forestry areas (3,184 ha). It was found to support a number of IUCN listed threatened and endangered species including rhino and tiger; and contains suitable habitat for a number of other endangered species. Owing to its connectivity, linking Chitwan National Park with the Mahabharat range, BFC has the potential to make an important contribution to improving the ecological integrity in Nepal. Different institutions and governance structures currently exist to manage the northern BFC. Although these institutions differ in resource utilization and benefit sharing mechanisms, they are united to safeguard the habitat of key wildlife species including rhino and tiger. We propose that the northern BFC should be managed through a new participatory scheme, the Barandabhar Forest Management Council, to foster ecological integrity of the area while providing forest products to communities. | View Paper |
| Species Movement and Dispersal, Species Richness | Ascensão, Fernando & Mira, Antonio. (2006). Factors affecting culvert use by vertebrates along two stretches of road in southern Portugal. Ecol Res. 22. 57-66. 10.1007/s11284-006-0004-1. | A major target for environmental managers when trying to minimise the road-barrier effect on wildlife is to improve permeability to animal movements. Previous studies have demonstrated that drainage culverts are used by vertebrates, although knowledge of the main influencing factors remains limited. The use of 34 culverts from two roads in southern Portugal, differing in traffic volume, vehicle speeds and configuration, was evaluated by the analysis of terrestrial vertebrate footprint data (408 passage-operative days). Culvert crossings were related to various explanatory variables by means of canonical ordination techniques. We recorded 901 complete crossings, corresponding to an average of 2.2 crossings/culvert/operative day. Thirteen taxa were detected, all in more than one passage. Animal species included reptiles, small mammals, lagomorphs, carnivores and domestic dogs and cats. Our results suggest that fencing might have a funnelling effect, directing larger animals toward culverts. Also, vegetation covering culvert entrances seems to have a positive effect, particularly on genets; longer passages with entrances far from the pavement were, apparently, avoided by smaller animals; a lower number of crossings was detected on passages with detritus pits; the closest passages to urban areas are more often used by domestic species; forest-living species favour passages with low, open land cover nearby; and smaller species, like lagomorphs and small mammals, appear to use more culverts near the pavement, which probably reflects the importance of road verges as refuges for these species. Although not used by all species present in the study area, constructing numerous passages of different sizes without detritus pits and which are distributed along roads might be an important step in mitigating road fragmentation effects on animal populations. | View Paper |
| Species Movement and Dispersal, Benefits to Local Community | Atela, Joanes. (2013). Governing REDD+ Governing REDD+: global framings versus practical evidence from the Kasigau Corridor REDD+ Project, Kenya. STEPS CENTRE. Working Paper No 55. | This paper explores the governance and feasibility of globally-linked REDD+ projects in local African settings, focusing on the Kasigau project in Kenya – Africa's first REDD+ project accredited under internationally accepted standards. The project is a commercial venture and during the last five years, it has unfolded in a relatively vulnerable Kenyan setting. A policy process analysis, interactive fieldwork and document review explored its interrelationship with local livelihood assets and state institutional capabilities. The paper reveals that while REDD+ institutions are globally standardised through negotiations interlocked with political and development interests, projects are faced with state and local resource histories and perceptions and in responding to such settings, such projects become highly contextual in practice. The paper concludes that communal systems, if well-defined, may provide a better basis for the governance of REDD+ projects, enabling inclusivity, collective action and societal benefits. If projects can genuinely enable local people to manage and benefit from their forest resources, REDD+ promises to be a multi-governance program that bridges the gap between global and local institutions and interests in the sustainable use of forests. | View Paper |
| Species Movement and Dispersal | Baker, L.. (2007). Effect of corridors on the movement behavior of the jumping spider Phidippus princeps (Araneae, Salticidae). Canadian Journal of Zoology. 85. 802-808. 10.1139/Z07-061. | Corridors are a common conservation strategy intended to increase the spatial connectivity among isolated habitat patches. Corridors, however, are not always effective. This study demonstrates that corridors increase movement to new patches for the jumping spider Phidippus princeps (Peckham and Peckham, 1883) (Araneae, Salticidae), a visually oriented predator. I assigned spiders to one of three microlandscape treatments, created in an old field dominated by alsike clover (Trifolium hybridum L.) and alfalfa (Medicago sativa L.), in which patches were connected to (i) vegetated corridors and bare pathways, (ii) only vegetated corridors, and (iii) only bare pathways. The movement of P. princeps was effectively directed by corridors. When given a choice of paths, spiders invariably chose vegetated corridors over bare pathways to emigrate from and to immigrate to new patches. Spiders rarely moved between patches when only bare pathways were available. In the absence of corridors, P. princeps did not risk open ground to move to new habitat even though conspecific density was high. The corridors facilitated the interpatch movement of P. princeps, suggesting that P. princeps is restricted in its habitat use. Thus, a higher degree of spatial connectivity is likely to increase the exchange of individuals for species that are restricted in their movements by unsuitable habitat. | View Paper |
| Species Richness | Barlow, Jos & Louzada, Julio & Parry, Luke & Hernández, Malva & Hawes, Joseph & Peres, Carlos & Vaz-de-Mello, Fernando & Gardner, Toby. (2010). Improving the design and management of forest strips in human-dominated tropical landscapes: A field test on Amazonian dung beetles. Journal of Applied Ecology. 47. 779 - 788. 10.1111/j.1365-2664.2010.01825.x. | 1. The future of tropical forest species depends in part on their ability to survive in human-modified landscapes. Forest strips present a priority area for biodiversity research because they are a common feature of many managed landscapes, are often afforded a high level of legal protection, and can provide a cost-effective and politically acceptable conservation strategy. 2. Despite the potential conservation benefits that could be provided by forest strips, ecologists currently lack sufficient evidence to inform policy and guide their design and management. 3. We used a quasi-experimental landscape in the Brazilian Amazon to test the importance of four management-relevant variables (forest type, isolation distance, forest structure, and large mammal activity) on the potential biodiversity conservation value of narrow forest strips for dung beetles. 4. Information-theoretic model selection based on AICc revealed strong support for the influence of large mammal activity and forest type on dung beetle abundance; isolation distance on species richness; and forest structure on the relative abundance of matrix-tolerant species. Multi-dimensional scaling showed a strong influence of forest type and isolation on community composition and structure, with riparian and dry-land strips having complementary sets of species. 5. Synthesis and applications. To enhance the conservation value and ecological integrity of forest strips in human-modified landscapes we recommend that strip design considers both isolation distance and whether or not the strips encompass perennial streams. In addition, we identify the maintenance of forest structure and the protection of large mammal populations as being crucially important for conserving forest dung beetle communities. | View Paper |
| Population Abundance,Species Movement and Dispersal | Beier, P., & Noss, R. F. (1998). Do habitat corridors provide connectivity?. Conservation biology, 12(6), 1241-1252. | Skeptics have questioned the empirical evidence that corridors provide landscape connectivity. Some also have suggested dangers of corridors. We reviewed published studies that empirically addressed whether corridors enhance or diminish the population viability of species in habitat patches connected by corridors. A randomized and replicated experimental design has not been used — and we argue is not required — to make inferences about the conservation value of corridors. Rather, studies can use observational or experimental analyzes of parameters of target populations or movements of individual animals. Two of these approaches hold the greatest promise for progress, especially if the shortcomings of previous studies are remedied. First, experiments using demographic parameters as dependent variables — even if unreplicated — can demonstrate the demographic effects of particular corridors in particular landscapes. Such studies should measure demographic traits before and after treatment in both the treated area (corridor created or destroyed) and an untreated area (habitat patches isolated from one another). This approach is superior to observing the demographic conditions in various landscapes because of the tendency for corridor presence to be correlated with other variables, such as patch size, that can confound the analysis. Second, observations of movements by naturally dispersing animals in fragmented landscapes can demonstrate the conservation value of corridors more convincingly than can controlled experiments on animal movement. Such field observations relate directly to the type of animals (eg, dispersing juveniles of target species) and the real landscapes that are the subject of decisions about corridor preservation. Future observational studies of animal movements should attempt to detect extra-corridor movements and focus on fragmentation-sensitive species for which corridors are likely to be proposed. Fewer than half of the 32 studies we reviewed provided persuasive data regarding the utility of corridors; other studies were inconclusive, largely due to design flaws. The evidence from well-designed studies suggests that corridors are valuable conservation tools. Those who would destroy the last remnants of natural connectivity should bear the burden of proving that corridor destruction will not harm target populations. Do Habitat Corridors Provide Connectivity? Some skeptics have questioned the empirical evidence that corridors provide connectivity to the landscape. Others have suggested the dangers of corridors. We review published studies that empirically addressed whether corridors enhance or decrease the viability of species populations in patches of habitat connected by corridors. To date, no replicated, randomized experimental design has been conducted to make inferences about the value of corridors in conservation — and we argue that it is not necessary. Instead, studies may employ observational or experimental analysis of parameters from populations of interest or individual movements of animals. Two of these approaches are very promising and can be progressed, especially if the limitations of previous studies are remedied. First, experiments that use demographic parameters as dependent variables — even if they are not replicated — can demonstrate demographic effects of corridors in particular landscapes. These studies should measure demographic characteristics before and after treatment, both in the treated area (corridor created or destroyed) and in an untreated area (habitat patches isolated from each other). This approach is superior to observing the demographic conditions in various landscapes since the presence of a corridor tends to be correlated with other variables, such as the size of the patch, which can confuse the analysis. Second, Observations of movements of normally moving animals in fragmented landscapes can demonstrate the value of corridors in conservation more convincingly than controlled experiments on moving animals. These types of field observations are directly related to the type of animal (eg, juveniles of the species of interest dispersing) and to the type of landscapes that are subject to corridor preservation decisions. Observational studies of animal movements in the future should try to detect extra-corridor movements and focus on species sensitive to fragmentation and for which corridors are feasible to be proposed. Less than half of the 32 studies reviewed provide persuasive data regarding the usefulness of corridors; other studies were inconclusive, mostly due to faulty designs. Evidence from well-designed studies suggests that corridors are valuable conservation tools. Those attempting to destroy the last remnants of natural connectivity should support themselves by demonstrating that the destruction of corridors will not affect populations of interest. | View Paper |
| Genetic Variation, Species Richness, Population Abundance, Species Movement and Dispersal, Plant Dispersal, Invasive Species, Ecosystem Services, Benefits and Consequences For Local Communities | Beier, Paul & Loe, S.. (1992). Checklist for evaluating impacts to wildlife movement corridors. Wildlife Society Bulletin. 20. 434-440. | The authors describe important functions of wildlife corridors, identify 2 classes of corridor users, and propose a series of steps to evaluate wildlife corridors with reference to these functions and user types. Their primary goal is to provide writers and critics of environmental impact analyses with a basis for developing measures that will avoid and mitigate impacts on wildlife movements. A second are related goal is to advocate that development projects bear the cost of monitoring animal use of the corridors created by those projects, so that hypotheses about corridor design can be tested. | View Paper |
| Species Richness | Benítez-López, Ana & Alkemade, Rob & Verweij, P.A.. (2010). The impacts of roads and other infrastructure on mammal and bird populations: A meta-analysis. Biological Conservation. 143. 1307-1316. 10.1016/j.biocon.2010.02.009. | Biodiversity is being lost at an increased rate as a result of human activities. One of the major threats to biodiversity is infrastructural development. We used meta-analyses to study the effects of infrastructure proximity on mammal and bird populations. Data were gathered from 49 studies on 234 mammal and bird species. The main response by mammals and birds in the vicinity of infrastructure was either avoidance or a reduced population density. The mean species abundance, relative to non-disturbed distances (MSA), was used as the effect size measure. The impact of infrastructure distance on MSA was studied using meta-analyses. Possible sources of heterogeneity in the results of the meta-analysis were explored with meta-regression. Mammal and bird population densities declined with their proximity to infrastructure. The effect of infrastructure on bird populations extended over distances up to about 1 km, and for mammal populations up to about 5 km. Mammals and birds seemed to avoid infrastructure in open areas over larger distances compared to forested areas, which could be related to the reduced visibility of the infrastructure in forested areas. We did not find a significant effect of traffic intensity on the MSA of birds. Species varied in their response to infrastructure. Raptors were found to be more abundant in the proximity of infrastructure whereas other bird taxa tended to avoid it. Abundances were affected at variable distances from infrastructure: within a few meters for small-sized mammals and up to several hundred meters for large-sized mammals. Our findings show the importance of minimizing infrastructure development for wildlife conservation in relatively undisturbed areas. By combining actual species distributions with the effect distance functions we developed, regions sensitive to infrastructure development may be identified. Additionally, the effect distance functions can be used in models in support of decision making on infrastructure planning. | View Paper |
| Species Movement and Dispersal | Bennett, A.F., 1990. Habitat corridors: Their role in wildlife management and conservation.Arthur Rulah Institute for Environmental Research. Department of conservation andenvironment, Melbourne. | Habitat loss and isolation associated with land conversion for human activities pose perhaps the most severe threat to the earth's biological diversity. Because the study of habitat fragmentation provides an important link between the concepts of landscape ecology and the practice of landscape architecture and planning, my dissertation research focused on the ecological consequences of changes in the spatial characteristics of native habitats. I completed two major field experiments with insects in a native grassland near Boulder, Colorado, USA, that directly tested ecological hypotheses regarding the influences of habitat spatial characteristics and patterns of land conversion on species loss, recolonization, and movement patterns. The first experiment focused on fragment size and connectivity, while the second experiment mimicked four sequences of land conversion that varied in size, connectivity and spatial arrangement of their remnant habitat patches. Both experiments yielded significant results that contribute to the ecological knowledge-base utilized in landscape architecture and planning projects. Specifically, the major findings of my field research were (1) fragment size influenced species loss; small fragments lost species at a higher rate than did larger fragments; (2) corridors reduced rates of species loss, but only in medium-sized fragments; (3) corridors enhanced recolonization of medium-sized fragments, (4) one of the three insect species examined moved preferentially in corridors; and (5) spatial configuration of land conversion sequences significantly influenced species richness. | View Paper |
| Species Movement and Dispersal | Bennett, Andrew & Saunders, Denis. (2011). Habitat Fragmentation and Landscape Change. 10.1093/acprof:oso/9780199554232.003.0006. | Conceptual approaches used to understand conservation in fragmented landscapes are summarized in this chapter by Andrew F. Bennett and Denis A. Saunders. Destruction and fragmentation of habitats are major factors in the global decline of species, the modification of native plant and animal communities and the alteration of ecosystem processes. Habitat destruction, habitat fragmentation (or subdivision) and new forms of land use are closely intertwined in an overall process of landscape change. Landscape change is not random: disproportionate change typically occurs in flatter areas, at lower elevations and on more-productive soils. Altered physical processes (e.g. wind and water flows) and the impacts of human land-use have a profound influence on fragments and their biota, particularly at fragment edges. Different species have different ecological attributes (such as scale of movement, life-history stages, what constitutes habitat) which influence how a species perceives a landscape and its ability to survive in modified landscapes. Differences in the vulnerability of species to landscape change alter the structure of communities and modify interactions between species (e.g. pollination, parasitism). Changes within fragments, and between fragments and their surroundings, involve timelags before the full consequences of landscape change are experienced. Conservation in fragmented landscapes can be enhanced by: (i) protecting and increasing the amount of habitat: (ii) improving habitat quality; (iii) increasing connectivity; (iv) managing disturbance processes in the wider landscape; (v) planning for the long term; and (vi) learning from conservation actions undertaken. | View Paper |
| Species Movement and Dispersal | Bennett, Andrew. (1990). Habitat Corridors and the Conservation of Small Mammals in a Fragmented Forest Environment. Landscape Ecology. 4. 109-122. 10.1007/BF00132855. | At Naringal in south-western Victoria, Australia, clearing of the original forest environment has created an agricultural landscape dominated by grazed pastures of introduced grasses. Remnant forest vegetation is re-stricted to small patches of less than 100 ha in size, that are loosely linked by narrow forested strips along road reserves and creeks. Six native and two introduced species of small terrestrial mammal (< 2 kg) occur within this environment. The native mammals, being dependent upon forest vegetation, were less tolerant to forest fragmentation than were the introduced species that also persist in farmland and farm buildings. The native mammals displayed an increasing frequency of occurrence in successively larger size-classes of forest patches. Those species with the greatest body-weight were the most vulnerable to habitat loss. All species of small mammal occurred in narrow habitat corridors of forest vegetation on roadsides. The resident status, seasonal variation in relative abundance, patterns of reproduction, and movements of each species were monitored in two habitat corridors during a 25-month trapping study. The corridors were found to facilitate continuity between otherwise-isolated populations of small mammals in this locality in two ways: firstly, by providing a pathway for the dispersal of single animals between patches; and secondly, by enabling gene flow through populations resident within the corridors. The small size of forest remnants at Naringal, and the vulnerability of species with low population sizes, emphasize the importance of preserving a mosaic of numerous habitat patches that together will support regional populations of sufficient size for longer-term persistence. The continuity between remnant habitats that is provided by a network of habitat corridors is an essential, and critical, component of this conservation strategy. | View Paper |
| Species Movement and Dispersal, Species Richness | Bennett, Andrew. (1991). Roads, roadsides and wildlife conservation: a review. Nature conservation 2: the role of corridors. 99-117. | Road reserves provide habitat for wildlife. Roadside vegetation has greatest value as a wildlife habitat when it comprises remnant or regenerated strips of indigenous vegetation. Road, roadside habitats and the aerial space above roads can facilitate the movement of animals along the direction of the road reserve. Road reserves can act as a filter or barrier to the movements of wildlife through the landscape, thus dividing and isolating populations to varying extents. Roads are a source of mortality for wildlife. For some species, particularly those that are large, rare, or are regularly brought into contact with busy roads, road-kills can have a significant effect on conservation status. Road systems are a source of biotic and abiotic effects on the surrounding landscape. -from Author | View Paper |
| Influencing Animal Behavoir | Bider, J. R. (1968). Animal activity in uncontrolled terrestrial communities as determined by a sand transect technique. Ecological Monographs, 38, 269-308. | View Paper | |
| Ecosystem Services, Population Abundance, Species Richness | Blacker, Amy & Jones, Darryl. (2008). Temporal trends in use of fauna-friendly underpasses and overpasses. CSIRO Wildlife Research. 35. 10.1071/WR07027. | The impact of roads on local biodiversity is a major issue associated with urbanisation. A major arterial road in the southern suburbs of Brisbane, south-east Queensland, was upgraded in 2004–05 from two to four lanes. In an attempt to minimise the impact of the larger road on local wildlife populations, a range of fauna crossing structures were constructed at the site. Monitoring of road-kill was undertaken for 4 months before construction and after the completion of construction. Assessment of the use of two underpasses and a large overpass ('land-bridge') started 6 months after construction using sand tracking in underpasses and scat sampling on the land-bridge. An initial 26-week period of intensive monitoring was undertaken from August 2005 to February 2006 followed by monthly monitoring from June 2006 to June 2007. On average, 1–5 tracks per day were detected in the underpasses at the start of the survey, increasing steadily to ~42 tracks per day by February 2006. The monthly survey showed regular use of the underpasses by a wide range of species and species-groups, the most abundant being 'rodents', most likely Rattus species, both native and introduced. The land-bridge was also used continuously by three species of macropod (red-necked wallaby, Macropus rufogriseus; swamp wallaby, Wallabia bicolor; and eastern grey kangaroo, Macropus giganteus) with brown hare (Lepus capensis) becoming increasingly common in summer 2006. The exclusion fencing was extremely effective in preventing most road-kill, at least of larger species, except following human-related breaches in the fence. | View Paper |
| Population Abundance | Boarman, William & SAZAKI, MARC & Jennings, W.. (1997). The Effect of Roads, Barrier Fences, and Culverts on Desert Tortoise Populations in California, USA. Proceedings of the international conference on conservation, restoration and management of tortoises and turtles. | Roads and highways pose several direct and indirect threats to turtle and tortoise populations. As barriers they inhibit dispersal and subsequent gene flow between subpopulations and metapopulations. In providing access to turtle and tortoise populations, they foster such threats as development, vandalism, and collecting. Increased diversity and productivity of vegetation, resulting from enhanced hydrological con- ditions beside roads, attracts tortoises, which place them at greater risk of direct mortality from both preda- tors and motorized vehicles. Roadkills are a substantial source of mortality in desert tortoises, Gopherus agassizii, in California (USA) as evidenced by data on roadkills from two highways. Desert tortoise populations are depauperate along high- ways and this depression may extend for at least 0.8 km or more from the road. Our study of the movements of desert tortoises equipped with radio transmitters suggests that tortoises living near highways move consid- erable distances over short periods of time and that these movements may place the tortoises at great risk of traffic-related mortality. Other studies show that common ravens, Corvus corax, predators on juvenile desert tortoises, are more common along heavily-traveled roads than away from them. A 24 km long tortoise-proof fence was erected along one highway in California. The barrier fence is made of 60 cm wide, l cm mesh hardware cloth, sunk 15 cm into the ground. The fence is supported by a 1.5 m high, six-strand wire fence. Several storm drain culverts span the highway. We report on a project that is now underway to monitor the effectiveness of the fence in preventing roadkills and facilitating the recovery of the local tortoise population. We are also measuring use of the culverts by tortoises to determine whether storm drain culverts are an effective mitigation for the fragmenting effects of the fence and highway. Causes of increased mortality and reduced natality must be investigated when a population of animals is declining to the point of being threatened with extirpation. When the causes are known, actions to reverse the population declines must be developed and implemented. However, before broad application, the action should be tested in a realistic setting, particularly when the action may be costly in terms of resources (financial, material, or human) or public relations. Desert tortoise, Gopherus agassizii, populations in the Mojave and Colorado deserts of the southwestern United States of America are listed as "Threatened" by the United States Fish and Wildlife Service (USFWS, 1990). Several of these populations are suffering rapid declines from many causes including disease, predation by ravens, on- and off- road vehicle traffic, livestock grazing, and loss of habitat (USFWS, 1994). Many various and complex human uses of the desert have cumulative, harmful effects on the tortoises. We report here on the harm highway traffic has on desert tortoise populations and on the progress of research to de- termine the effectiveness of barrier fences to decrease the harm. | View Paper |
| Species Movement and Dispersal | Borda de Agua, Luis & Navarro, Laetitia & Gavinhos, Catarina & Pereira, Henrique. (2011). Spatio-temporal impacts of roads on the persistence of populations: Analytic and numerical approaches. Landscape Ecology. 26. 253-265. 10.1007/s10980-010-9546-2. | Roads can have drastic impacts on wildlife populations. Although there is wide recognition of the negative impacts caused by roads and a wealth of practical studies, there is a lack of theoretical work that can be used to predict the impact of road networks or to implement mitigation measures. Here, using Skellam’s diffusion model, we develop analytic and numerical approaches to analyze the impact of road networks on the survival of populations. Our models show that the viability of a population is determined not only by road density but also by the size and shape of patches. Accordingly, we studied the minimum size of a patch to sustain a population with given diffusion and growth parameters. We provide simple formulas to estimate the minimum patch size, and illustrate the importance of shape with square and rectangular patches. Our models also allow the estimation of time to extinction after road construction for a population in a patch smaller than that of the minimum size. Finally, using numerical computations we illustrate how the spatial arrangement of fences strongly affects both the equilibrium density and the spatial distribution of populations, and that not all fence layouts are equally effective. We anticipate that our methods provide a tool to assess the impact of geometrical features of road networks on wildlife and that they can be used to design mitigation measures to prevent the decline and extinction of populations in an anthropogenically disturbed landscape. KeywordsSkellam’s model–Reaction–diffusion equations–Dispersal–Road mortality–Mitigation measures–Fences–Spatially explicit model–Minimum patch size–Patch shape | View Paper |
| Species Movement and Dispersal | Bowler, Diana & Benton, Tim. (2005). Causes and consequences of animal dispersal strategies: Relating individual behaviour to spatial dynamics. Biological reviews of the Cambridge Philosophical Society. 80. 205-25. 10.1017/S1464793104006645. | Knowledge of the ecological and evolutionary causes of dispersal can be crucial in understanding the behaviour of spatially structured populations, and predicting how species respond to environmental change. Despite the focus of much theoretical research, simplistic assumptions regarding the dispersal process are still made. Dispersal is usually regarded as an unconditional process although in many cases fitness gains of dispersal are dependent on environmental factors and individual state. Condition-dependent dispersal strategies will often be superior to unconditional, fixed strategies. In addition, dispersal is often collapsed into a single parameter, despite it being a process composed of three interdependent stages: emigration, inter-patch movement and immigration, each of which may display different condition dependencies. Empirical studies have investigated correlates of these stages, emigration in particular, providing evidence for the prevalence of conditional dispersal strategies. Ill-defined use of the term 'dispersal', for movement across many different spatial scales, further hinders making general conclusions and relating movement correlates to consequences at the population level. Logistical difficulties preclude a detailed study of dispersal for many species, however incorporating unrealistic dispersal assumptions in spatial population models may yield inaccurate and costly predictions. Further studies are necessary to explore the importance of incorporating specific condition-dependent dispersal strategies for evolutionary and population dynamic predictions. | View Paper |
| Species Movement and Dispersal | Braden, Anthony & Lopez, Roel & Roberts, Clay & Silvy, Nova & Owen, Catherine & Frank, Philip. (2008). Florida Key deer Odocoileus virginianus clavium underpass use and movements along a highway corridor. Wildlife Biology - WILDLIFE BIOL. 14. 155-163. 10.2981/0909-6396(2008)14[155:FKDOVC]2.0.CO;2. | In order to address endangered Florida Key deer Odocoileus virginianus clavium vehicle collisions along a 5.6-km segment of United States Highway I (US 1), the Florida Department of Transportation (FDOT) constructed a 2.6-km long system of fencing, deer guards and two underpasses to exclude deer from roadway. The US I project was completed in 2002 for the purpose of minimizing Key deer mortality and maintaining deer permeability through the Big Pine Key (BPK) corridor, Florida, USA. We evaluated the potential impact of these modifications to Key deer movements by comparing 1) annual ranges and movements of Key deer pre- (January 1998 - December 2000) and post-construction (February 2003 - January 2004), 2) deer-vehicle collisions on US I pre- and post-construction, and 3) underpass use post-construction. Mean female and male annual ranges and core areas did not change (P > 0.05) between pre- and post-construction. Deer movements within the US I project area were comparable pre- (six of 23 radio-collared deer crossed the corridor) and post-project (four of 16). Key deer-vehicle collisions were reduced by 94% inside the fenced segment. Experimental deer guards and fencing minimized Key deer entry into the project area to eight deer during the first-year resulting in two deer mortalities (one deer-vehicle collision, one severe removal injury). Infrared-triggered camera data indicate that underpass movements increased over time, suggesting that an acclimation period is necessary for highway underpasses to be successful. Collectively, post-project data indicate that highway alterations have not restricted Key deer permeability while minimizing Key deer mortality; however, our study results suggest changes in deer movement patterns within the corridor. We recommend continued monitoring to verify accurate trends in deer use of wildlife underpasses and permeability across fenced areas. | View Paper |
| Species Movement and Dispersal | Brinkerhoff, Robert & Haddad, Nick & Orrock, John. (2005). Corridors and olfactory cues affect small mammal behaviour. JOURNAL OF MAMMALOGY. 86. 662-669. 10.1644/1545-1542(2005)086[0662:CAOPCA]2.0.CO;2. | The behavior of prey individuals is influenced by a variety of factors including, but not limited to, habitat configuration, risk of predation, and availability of resources, and these habitat-dependent factors may have interactive effects. We studied the responses of mice to an increase in perceived predation risk in a patchy environment to understand how habitat corridors might affect interactions among species in a fragmented landscape. We used a replicated experiment to investigate corridor-mediated prey responses to predator cues in a network of open habitat patches surrounded by a matrix of planted pine forest. Some of the patches were connected by corridors. We used mark-recapture techniques and foraging trays to monitor the movement, behavior, and abundance of small mammals. Predation threat was manipulated in one-half of the replicates by applying an olfactory predator cue. Corridors synchronized small mammal foraging activity among connected patches. Foraging also was inhibited in the presence of an olfactory predator cue but apparently increased in adjacent connected patches. Small mammal abundance did not change as a result of the predator manipulation and was not influenced by the presence of corridors. This study is among the 1st to indicate combined effects of landscape configuration and predation risk on prey behavior. These changes in prey behavior may, in turn, have cascading effects on community dynamics where corridors and differential predation risk influence movement and patch use | View Paper |
| Species Movement and Dispersal | Brodziewska, J. 2005. Wildlife Tunnels and Fauna Bridges in Poland: Past, Present and Future, 1997-2013. 9. Teixeira, F. Z., Printes, R. C., Fagundes, J. C. G., Alonso, A. C., & Kindel, A. 2013. Canopy bridges as road overpasses for wildlife in urban fragmented landscapes. Biota Neotropica, 13(1), 117–123. doi: 10.1590/s1676-06032013000100013 | In Poland the road and rail network crosses many sensitive areas, such as national parks, landscape parks, wildlife reserves, landscape protection areas and Natura 2000 sites, i.e., the protected area system of the European Union, because of road density, high landscape diversity, and its mosaic pattern. As a consequence of Poland joining the European Union in 2004, many changes have happened and are still happening all over the country, especially in building new roads and railway lines. The harmonization of the Polish legal system with the EU directives required the improvement of environmental legislation making the monitoring before and after the building of such constructions necessary together with the preparation of environmental assessment studies. The animal migration problem has become one of the most important barriers in the decision-making process on where to build new roads and improve others. According to the previous plans, most of the roads that should have become expressways or highways of national or international importance also bring higher traffic and driving speed in those areas. As a consequence, the risk of collisions became higher and many motorists died in fatal accidents. On average, on the 160-km A2 highway running from Nowy Tomyśl to Konin, 40 accidents with mammals were recorded in one month in 2003. The consciousness of the society grew enormously following these events, and it also urged the appropriate governmental institutions, as well as private companies, investors, and non-governmental organizations, to study animals along the roads all over the country, with special attention to their movement. As a first step toward solving this problem, the identification of animal migration routes became an important task. Besides large species that can cause the death of the driver when colliding with a car (such as elk, deer, wild boar), several smaller animals (such as fox, badger, amphibians or reptiles) with vulnerable populations in the surveyed area were also studied, and the building of passages and bridges for wildlife has become not only an obligation but also a necessity both at the constructor as well as at the social level. Since 1997 more than ten overpasses and one underpass were built for large mammals (elk, deer, wolf, wild boar) in Poland. They are located along the E65 international road, Katowice - Kraków and the Przylesie - Nowogowczyce sections of the A4 highway, Poznan - Nowy Tomyśl and Nowy Tomyśl - Konin sections of the A2 highway, Stryszek- Białe Błota section of the no. 10. national road, and Komorniki - Stęszewo section of the no. 5. national road. The decision about the exact location of the game bridges and the game passage was made after detailed interviews with national park officials and foresters, in addition to the results of field work. The monitoring of the effectiveness of these constructions revealed a lot of mistakes and often proved no use of the mitigation measures by the target animals. The main reasons for non-functioning were too-small dimensions, especially width in all of game bridges; lack of screens separating the animals from noise; vibration, light and visual disturbances, no or not enough vegetation on the bridges; lack of guiding structures leading the animals to the passages; and lack of fences along the road. As a consequence of such results, mitigation measures were improved and maintained better. For small mammals, amphibians, and reptiles, nine underpasses were built in 2004 along the Budzisko - Augustów section of the international road called Via Baltica, Jeleniów section of the local road next to the E67 international road, and Chabówka - Rdzawka section of the E 47 expressway. The decision about where to put tunnels was made on the basis of field research (day and night transects, the sound monitoring of amphibians, and amphibian breeding sides investigations) made by national park staff, private companies, and volunteers. The follow-up monitoring of these structures showed that the effectiveness of the tunnels with guiding structures is nearly 100 percent for amphibians and reptiles and 85 percent for small mammals. In the following nine years (2005-2013) several more wildlife passages will be built on Polish roads along the Łódź - Częstochowa section of the A1 highway, Przylesie - Prądy section of the A4 highway, Rosnówek section of the no. 5. national road, Zywiec - Zwardoń section of the S69 international road, Wyszków - Skuszew section of the no. 8. national road, and Poznań - Kórnik section of the no. 11. national road. From among these constructions the most important passages will be along the Zywiec – Zwardoń section of the S69 international road, as they will be aimed to protect wildlife of international importance (bears, lynx, and wolves). | View Paper |
| Species Movement and Dispersal | Brook, B. W., Sodhi, N. S., & Bradshaw, C. J. (2008). Synergies among extinction drivers under global change. Trends in ecology & evolution, 23(8), 453-460. | If habitat destruction or overexploitation of populations is severe, species loss can occur directly and abruptly. Yet the final descent to extinction is often driven by synergistic processes (amplifying feedbacks) that can be disconnected from the original cause of decline. We review recent observational, experimental and meta-analytic work which together show that owing to interacting and self-reinforcing processes, estimates of extinction risk for most species are more severe than previously recognised. As such, conservation actions which only target single-threat drivers risk being inadequate because of the cascading effects caused by unmanaged synergies. Future work should focus on how climate change will interact with and accelerate ongoing threats to biodiversity, such as habitat degradation, overexploitation and invasive species. | View Paper |
| Species Richness | Brown et. al. Comanagement of wildlife corridors: the case for citizen participation in the Algonquin to Adirondack proposal | The debate between top-down and bottom-up planning has recently re-emerged in environmental management. Many commentators agree on the merits of comanagement, in which affected citizens and professional managers share responsibility for planning. Nevertheless, the manifold advantages of comanagement have not always been fully appreciated in environmental planning. For example, a group representing NGOs and academic institutions recently proposed an ecological corridor linking Algonquin Provincial Park in southern Ontario to the Adirondack Park in northern New York. This corridor, known as A2A, was designed to encourage the migration of wolves and other wildlife between the parks. Much of the land in A2A is private property. A survey of households, randomly scattered throughout the United States portion of the corridor, revealed that affected landowners had little knowledge of the proposal and no contact with its advocates. Many respondents were farmers who utilized land for livelihood. Other landowners enjoyed property for a variety of recreational purposes. Regardless of use, survey participants placed high value on the importance of conserving biological diversity. They also expressed great distrust toward restrictions that might be placed on their activities. In general, respondents felt very unsure about A2A, and they were uncertain about personal involvement in the planning process. Certain landowners indicated a willingness to have their land be included in an ecological corridor, despite not knowing about it before the survey was administered. These results suggest that A2A proponents have little to lose and much to gain by disseminating information locally and by embracing comanagement for further formulation of this plan. | View Paper |
| Invasive Species, Species Movement and Dispersal | Brown, Gregory P., Benjamin L. Phillips, Jonathan K. Webb, Richard Shine, Toad on the road: Use of roads as dispersal corridors by cane toads (Bufo marinus) at an invasion front in tropical Australia, Biological Conservation, Volume 133, Issue 1, 2006, Pages 88-94, ISSN 0006-3207, | Determining the factors that influence the rate of spread of invasive species is an important goal for conservation biology. If invasive species utilize specific landscape features as dispersal corridors, control programs can target such corridors. Radio-telemetry was used to determine landscape level factors that influence dispersal of an introduced anuran species (the cane toad) at an invasion front in tropical Australia. Most radio-tracked toads moved along roads and cleared fencelines, avoiding heavily vegetated habitat; they typically sheltered overnight close to these open corridors, returning to the road each evening to recommence dispersal. Surveys of the compass orientation of dispersing toads on roads showed that most animals were oriented along the main axis of the road (and thus, travelling along the road) rather than moving across it. To test the hypothesis that use of roads enables toads to disperse more rapidly than would be possible across more thickly vegetated sites, locomotor performance of toads was quantified under field conditions. As predicted, toads rapidly slowed down in dense roadside vegetation but continued to move rapidly through open areas. These results suggest that simple habitat manipulations of roadside verges might help to reduce the rate of dispersal of cane toads across tropical Australia. | View Paper |
| Influencing Animal Behavoir | Brown, J.H. and Kodric-Brown, A. (1977), Turnover Rates in Insular Biogeography: Effect of Immigration on Extinction. Ecology, 58: 445-449. https://doi.org/10.2307/1935620 | Demographic and genetic contributions from conspecific immigrants tend to reduce extinction rates of insular populations. The MacArthur—Wilson model of island biogeography is modified to provide for this effect of immigration on extinction, which we call the rescue effect. This new model predicts that when immigration rates are high relative to extinction rates, turnover rate is directly related to the distance between an island and the source of colonizing species. A field study of the distribution of arthropods among isolated plants supports the model. | View Paper |
| Species Movement and Dispersal | Brudin, C. O. (2003). Wildlife use of existing culverts and bridges in North Central Pennsylvania . | The Pennsylvania Department of Transportation (PENNDOT) District 3-0 initiated a study in North Central Pennsylvania evaluating existing bridges and culverts for use as underpasses by wildlife. This project was a two-phase study to investigate animal passage through existing drainage box culverts, arch culverts and bridges on existing highway systems. The objective of this study was to (1) determine whether wildlife are using existing structures as passageways based on wildlife sign and remote camera monitoring and (2) determine underpass dimensions, interior characteristics, location, topography, and adjacent habitat features that contribute to and enhance usage of underpass corridors by wildlife. These data will contribute to future highway design and mitigation measures in addressing wildlife corridors. | View Paper |
| Species Richness | Brudvig, L. A. (2016). Interpreting the effects of landscape connectivity on community diversity. Journal of Vegetation Science, 27, 4–5. | Landscape connectivity is considered a key factor regulating species diversity of natural and managed landscapes, yet the influence of connectivity relative to other factors remains poorly resolved. In this issue of Journal of Vegetation Science, Jakobsson and colleagues illustrate how grassland plant species richness is more strongly affected by the age and management of grassland patches than by connectivity. | View Paper |
| Ecosystem Services, Species Movement and Dispersal | Brudvig, L. A., Wagner, S. A., & Damschen, E. I. (2012). Corridors promote fire via connectivity and edge effects. Ecological Applications, 22(3), 937-946. doi: 10.1890/11- 1026.1 | Landscape corridors, strips of habitat that connect otherwise isolated habitat patches, are commonly employed during management of fragmented landscapes. To date, most reported effects of corridors have been positive; however, there are long‐standing concerns that corridors may have unintended consequences. Here, we address concerns over whether corridors promote propagation of disturbances such as fire. We collected data during prescribed fires in the world's largest and best replicated corridor experiment (Savannah River Site, South Carolina, USA), six ∼50‐ha landscapes of open (shrubby/herbaceous) habitat within a pine plantation matrix, to test several mechanisms for how corridors might influence fire. Corridors altered patterns of fire temperature through a direct connectivity effect and an indirect edge effect. The connectivity effect was independent of fuel levels and was consistent with a hypothesized wind‐driven “bellows effect.” Edges, a consequence of corridor implementation, elevated leaf litter (fuel) input from matrix pine trees, which in turn increased fire temperatures. We found no evidence for corridors or edges impacting patterns of fire spread: plots across all landscape positions burned with similar probability. Impacts of edges and connectivity on fire temperature led to changes in vegetation: hotter‐burning plots supported higher bunch grass cover during the field season after burning, suggesting implications for woody/herbaceous species coexistence. To our knowledge, this represents the first experimental evidence that corridors can modify landscape‐scale patterns of fire intensity. Corridor impacts on fire should be carefully considered during landscape management, both in the context of how corridors connect or break distributions of fuels and the desired role of fire as a disturbance, which may range from a management tool to an agent to be suppressed. In our focal ecosystem, longleaf pine woodland, corridors might provide a previously unrecognized benefit during prescribed burning activities, by promoting fire intensity, which may assist in promoting plant biodiversity. | View Paper |
| Genetic Variation | Burkart, Stephanie, et. al.. "Evaluating the functionality of expert-assessed wildlife corridors with genetic data from roe deer." Basic and applied ecology 17.1 (2016): 52-60. | Traffic infrastructure such as fenced motorways may reduce functional connectivity by impeding the movement of wildlife and thus reduce gene flow across landscapes. This may result in increased genetic differentiation, eventually leading to decreasing genetic diversity in wildlife populations owing to genetic drift. Landscape managers and conservation agencies apply a range of measures to mitigate such adverse effects in intensively managed landscapes. Efficient measures to facilitate landscape permeability for wildlife include expert-assessed wildlife corridors. However, whether wildlife corridors are used as such and whether they fulfill their purpose remains largely unknown. Here, we evaluated whether the expert-based categorization of wildlife corridors into functional, impaired and interrupted held true in the Swiss Plateau by testing the landscape's permeability using genetic assessments. We identified the spatial genetic structure of roe deer ( Capreolus capreolus) and tested, whether the estimated gene flow supported the expert categorization of wildlife corridors. Among the four study regions (approx. 300-2600 km 2 ), pairwise genetic differentiation was rather low ( F ST ranging between 0.008 and 0.0264). However, wildlife corridors identified as intact on the basis of expert evaluation showed higher gene flow between populations of roe deer (mean F ST = 0.008) than corridors classified as impaired or interrupted (mean F ST = 0.022). Thus, expert judgment on the functionality of wildlife corridors could be generally confirmed by our genetic assessment on the permeability of landscapes for roe deer. This shows that genetic methods may constitute a useful set of tools to identify the state of management measures and to prioritize action plans for maintaining functional wildlife corridors across landscapes. | View Paper |
| Species Movement and Dispersal | Cain et. al.. Effects of a highway and mitigation projects on bobcats in Southern Texas | Roads are a common landscape feature that may negatively impact wildlife. These impacts may be reduced by altering roads and their right-of-ways. We studied impacts of a 4-lane divided highway on bobcats (Lynx rufus) in southern Texas. From June 1997 to May 1999, 25 bobcats were found dead on the 32.2 km section of highway we studied. Mortalities were more likely adjacent to habitat preferred by bobcats and in sections of the highway in which thornshrub had been left in the median. Bobcats used culverts to cross under the highway and for other activities, such as resting. Culvert use was positively related to the openness ratio (width×height/length) of the culvert and to the amount of thornshrub cover adjacent to the culvert. Sections of fence 100 m long erected to funnel wildlife toward culverts did not increase bobcat use of culverts in an analysis of all culverts, but may have increased use of high-use culverts. Our results highlight the competing nature of techniques to minimize population fragmentation and mortality. Projects to reduce the impact of roads on wildlife should consider which impacts are likely to be most detrimental and ensure that efforts to mitigate one impact will not increase another. | View Paper |
| Invasive Species | Mann, Charles & Plummer, Mark. (1995). Are Wildlife Corridors the Right Path?. Science. 270. 1428-1430. 10.1126/science.270.5241.1428. | The popular strategy of connecting patches of otherwise isolated habitat is at the center of a major conservation debate. Many ecologists and conservation activists argue that such corridors are critical to maintaining biodiversity and could save many endangered species. But others counter that there is little evidence that animals need these corridors and that buying corridor land precludes spending money on more scientifically certain conservation efforts. | View Paper |
| Invasive Species | Canada, E. and C. C. (2007, October 15). Why invasive alien species are a problem [Guidance]. Aem. | According to the World Conservation Union, invasive alien species are the second most significant threat to biodiversity, after habitat loss. In their new ecosystems, invasive alien species become predators, competitors, parasites, hybridizers, and diseases of our native and domesticated plants and animals. It takes the right conditions for an alien species to become established and grow. In fact, most introduced species do not become permanently established in their newly found environment. They either find the wrong type of conditions for survival, or there they are unable to produce enough offspring to maintain a viable population. For those species that are able to reproduce and survive, most never cause significant problems. They survive, spread and reproduce but generally do not pose a risk to Canada’s economy, environment or society. | View Paper |
| Species Richness | Chen, Hsiang & Koprowski, John. (2011). Beckmann, J. P., A. P. Clevenger, M. P. Huijser, and J. A. Hilty (eds.). 2010. Safe Passages: Highways, Wildlife, and Habitat Connectivity. Island Press, Washington, D.C., 383 pp. price (paper), $40.00., ISBN 978-1-5972-6654-3.. Journal of Mammalogy. 92. 1140-1141. 10.1093/jmammal/92.5.1140. | Roads are conspicuous and pervasive features of landscapes throughout the world, measuring nearly 102,000,000 km in length worldwide (Central Intelligence Agency 2010). More than 20% of the land in the United States is affected by roads and traffic (Forman 2000). Road ecology, the study of interactions between organisms and road environments, is a rapidly developing field of inquiry. The thorough review of road impacts by Trombulak and Frissell (2000) set the standard to start the 21st century, and the 2003 edited volume, Road Ecology: Science and Solutions , by Forman et al. marked the emergence of this subdiscipline of ecology. Still an emerging field, the science of road ecology is expanding, with increased interest in integration of scientific research in decision-making on transportation planning, design, and construction. Current research focuses on reducing the barrier effect of roads, increasing landscape permeability, and improving motorists' safety. Safe Passages: Highways, Wildlife, and Habitat Connectivity by Beckmann et al. details the latest developments in road ecology studies and provides a toolbox for individuals and organizations engaged in reducing road–wildlife impacts. The book provides a state-of-our-knowledge assessment of theory and practice organized into 4 major sections: Current practices , Ecologically effective transportation … | View Paper |
| Benefits and Consequences For Local Communities | Chettri, Nakul & Sharma, Eklabya & Shakya, Bandana & Bajracharya, Birendra. (2007). Developing Forested Conservation Corridors in the Kangchenjunga Landscape, Eastern Himalaya. Mountain Research and Development. 27. 211-214. 10.1659/mrd.0923. | The Kangchenjunga landscape in the trans-boundary region of Nepal, Bhutan, and India has rich forest resources offering a wide range of ecosystem services to local people and habitats for many rare plant and animal species. Despite conservation efforts in several fragmented protected areas in the past, forest ecosystems and their multiple functions have been affected by over-extraction of resources, haphazard land use practices, intensive agriculture, overgrazing, unmanaged tourism, and unplanned infrastructure development. We describe a multi-level and multi-stakeholder transboundary process initiated in 2002 with the overall objective of restoring fragmented and deteriorating forest resources through development of conservation corridors and adaptation of conservation measures, moving from a species approach to a landscape approach. In collaboration with governmental and non-governmental organizations, academics, and communities, the International Centre for Integrated Mountain Development (ICIMOD) has been addressing the conservation issue by promoting participatory reforestation and transboundary collaboration, and linking conservation with sustainable use of resources by local communities. | View Paper |
| Invasive Species, Species Movement and Dispersal | Chovanec, Andreas & Schiemer, Fritz & Cabela, A. & Gressler, Sabine & Grötzer, C. & Pascher, Kathrin & Raab, Rainer & Teufl, H. & Wimmer, Reinhard. (2000). Constructed inshore zones as river corridors through urban areas - The Danube in Vienna: Preliminary results. Regulated Rivers: Research & Management. 16. 10.1002/(SICI)1099-1646(200003/04)16:2<175::AID-RRR578>3.0.CO;2-C. | Over the last 125 years, river regulation has considerably changed the ecological conditions of the Austrian Danube and its floodplains such that the system is now very fragmented. Within the municipal area of Vienna, these changes have been particularly severe: river embankments and a bypass channel (the ‘New Danube’), separated from the main river by an artificial island (‘Danube Island’), are the key elements of flood control, and river levels are controlled by the Vienna hydroelectric power plant (‘Freudenau’). During construction of the hydroelectric power plant, the previously straight shoreline of the 21-km long Danube island, with its steep embankments, was restructured by creating shallow water areas, gravel banks, small permanent backwaters and temporary waters. This paper describes the scheme and the results from the first year of a 4-year monitoring programme (‘Danube Island Monitoring Programme’, DIMP) investigating the colonization and successional processes of these areas by monitoring relevant indicator groups (vegetation, dragonflies, amphibians, reptiles, waterfowl). Copyright © 2000 John Wiley & Sons, Ltd. | View Paper |
| Species Movement and Dispersal | Clevenger, Anthony & Sawaya, Michael. (2010). Piloting a Non-Invasive Genetic Sampling Method for Evaluating Population-Level Benefits of Wildlife Crossing Structures. Ecology and Society. 15. 10.5751/ES-03248-150107. | Intuitively, wildlife crossing structures should enhance the viability of wildlife populations. Previous research has demonstrated that a broad range of species will use crossing structures, however, questions remain as to whether these measures actually provide benefits to populations. To assess this, studies will need to determine the number of individuals using crossings, their sex, and their genetic relationships. Obtaining empirical data demonstrating population-level benefits for some species can be problematic and challenging at best. Molecular techniques now make it possible to identify species, individuals, their sex, and their genetic relatedness from hair samples collected through non-invasive genetic sampling (NGS). We describe efforts to pilot a method to assess potential population-level benefits of wildlife crossing structures. We tested the feasibility of a prototype NGS system designed to sample hair from black bears (Ursus americanus) and grizzly bears (U. arctos) at two wildlife underpasses. The piloted hair-sampling method did not deter animal use of the trial underpasses and was effective at sampling hair from more than 90% of the bear crossing events at the underpasses. Hair samples were also obtained from non-target carnivore species, including three out of five (60%) cougar (Puma concolor) crossing events. Individual identification analysis revealed that three female and two male grizzly bears used one wildlife underpass, whereas two female and three male black bears were identified as using the other underpass. Of the 36 hair samples from bears analyzed, five failed, resulting in an 87% extraction success rate, and six more were only identified to species. Overall, 70% of the hair samples from bears collected in the field had sufficient DNA for extraction purposes. Preliminary data from our NGS suggest the technique can be a reliable method to assess the population-level benefits of Banff wildlife crossings. Furthermore, NGS can be an important tool for the conservation value of wildlife crossings for other taxa, and we urge others to carry out evaluations of this emerging methodology. | View Paper |
| Species Richness | Clevenger, Anthony & Waltho, Nigel. (2005). Performance indices to identify attributes of highway crossing structures facilitating movement of large mammals. Biological Conservation. 121. 453-464. 10.1016/j.biocon.2004.04.025. | Studies assessing the efficacy of wildlife crossing structures often lead to spurious results because of their failure to address masking effects of confounding variables. Confounding variables include variation in human activity, density of crossing structures along the highway corridor, and equality of species' perceived access to each crossing structure. We investigated these issues for wide-ranging large carnivores and their prey species in Banff National Park, Alberta, using data obtained from systematic, year-round monitoring of 13 newly constructed crossing structures for wildlife (underpasses and overpasses) for 34 months post-construction. We standardized the first confounding variable by selecting crossing structures remote from areas of human activity. The second confounding variable we standardized by developing probability models of crossing structure usage assuming habitat homogeneity. We standardized the third confounding variable by developing species-specific, performance indices of crossing structures (=observed through passage usage–expected through passage usage). We regressed the species performance indices against 13 crossing structure variables encompassing structural, landscape, and human activity. Our results suggest that in absence of high human activity structural attributes best explained the performance indices for both large predator and prey species, while landscape and human-related factors were of secondary importance. Crossing structures that were high, wide and short in length strongly influenced passage by grizzly bears Ursus arctos, wolves Canis lupus, elk Cervus elaphus, and deer Odocoileus sp. More constricted crossing structures were favoured by black bears Ursus americanus and cougars Puma concolor. Distance to cover was the most important crossing structure landscape attribute for cougars (negative correlation) and was a significant factor determining passage for grizzly bears, elk and deer (all positive correlations). Our findings underscore the importance of: (a) integrating temporal and spatial variability a priori when addressing the efficacy of crossing structures, and; (b) demonstrate that species respond differently to crossing structure features. In light of these results, we suggest that to maximize connectivity across roads for multiple large mammal species, road construction schemes should include a diversity of crossing structures of mixed size classes. Mitigation planning in a multiple-species ecosystem is likely to be a challenging endeavour and long-term research will aid in the decision-making process.prs.rt("abs_end");KeywordsBanff National Park; Habitat fragmentation; Mammals; Road ecology; Wildlife crossing structureFigures and tables from this article: | View Paper |
| Species Movement and Dispersal | Clevenger, A. P., Chruszcz, B., & Gunson, K. (2001). Drainage culverts as habitat linkages and factors affecting passage by mammals. Journal of Applied Ecology , 38 (6), 1340–1349. | 1. Drainage culverts are ubiquitous features in road corridors, yet little is known about the efficacy of culverts for increasing road permeability and habitat connectivity for terrestrial wildlife. Culvert use by small and medium-sized mammals was investigated along roads in Banff National Park, Alberta, Canada. An array of culvert types was sampled varying in dimensions, habitat and road features during the winters of 1999 and 2000. Expected passage frequencies were obtained by sampling relative species abundance along transects at the ends of each culvert. 2. Weasels Mustela erminea and M. frenata and deer mice Peromyscus maniculatus used the culverts for passage most frequently, whereas red squirrels Tamiasciurushudsonicus and snowshoe hares Lepusamericanus were the most common small mammals in the study area according to transects sampled near each culvert. 3. Species performance indices (observed crossing vs. expected crossing) were calculated for five species by comparing their tracks inside and adjacent to 36 culverts. Culvert performance indices were significantly different between the five species: culvert attributes influenced species use but different attributes appeared to affect use by different species. 4. At all scales of resolution (species, species group and community level), traffic volume, noise levels and road width ranked high as significant factors affecting species' use of the culverts. Passage by American martens Martesamericana, snowshoe hares and red squirrels all increased with traffic volume, the most important variable. Coyote Canislatrans use of culverts was negatively correlated with traffic volume. Increasing noise and road width appeared to be negative influences on culvert passage by coyotes, snowshoe hares and red squirrels. 5. Structural variables partially explained passage by weasels and martens. Weasel passage was positively correlated with culvert height but negatively correlated with culvert openness. Martens preferred culverts with low clearance and high openness ratios. High through-culvert visibility was important for snowshoe hares but not for weasels. The passage by weasels and snowshoe hares was positively correlated with the amount of vegetative cover adjacent to culverts. 6. For many small- and medium-sized mammals drainage culverts can mitigate the potentially harmful effects of busy transport corridors by providing a vital habitat linkage. To maximize connectivity across roads for mammals, future road construction schemes should include frequently spaced culverts of mixed size classes and should have abundant vegetative cover present near culvert entrances. Further work is required to assess the effects of culverts on population demography and gene flow adjacent to large roads. | View Paper |
| Species Movement and Dispersal | Clevenger, A. P., Chruszcz, B., & Gunson, K. E. (2001). Highway mitigation fencing reduces wildlife-vehicle collisions. Wildlife Society Bulletin, 646-653. | Road mortality can significantly impact some wildlife populations. However, few studies have assessed the effectiveness of measures to reduce wildlife-vehicle collisions (WVCs). We evaluated highway mitigation fencing to reduce WVCs along 3 4-lane sections (phase 1, 2, 3A) of the Trans-Canada highway in Banff National Park, Alberta. We collected data on WVCs and animal intrusions on the fenced right-of-way from 1981 to 1999. We found that WVCs were distributed nonrandomly after fencing and were associated with and close to fence ends. Wildlife-vehicle collisions were greatest within 1 km of fence ends, but proximity to major drainages also likely influenced location of collisions. Post-fencing WVCs were reduced effectively as ungulate-vehicle collisions declined 80%. Wildlife-vehicle collisions and animal intrusions onto the right-of-way were not associated with fence-access points. We recommend methods of modifying motorist behavior and fence design to decrease accident probability at fence ends. | View Paper |
| Species Movement and Dispersal | Clevenger, A.P. & Waltho, N. 2000. Factors influencing the effectiveness of wildlife underpasses in Banff National Park, Alberta, Canada. Conservation Biology, 14(1), 47-56. | Wildlife crossing structures are intended to increase perineability and habitat connectivity across roads. Few studies, however, have assessed the effectiveness of these mitigation measures in a Guilt species or community level context. We used a null model to test whether wildlife crossing structures serve large manimnal species equally or whether such structtures limit habitat connectivity across roads in species-specific ways. We also modeled species responses to 14 variables related to underpass structure, landscape features, and buman activity. Species perfornmance ratios (observed crossing frequency to expected crossinig frequency) wvere evaluated forfour large carnivore and three unguilate species in 11 underpass structures in Banif National Park, Alberta, Canada. Observed crossing frequencies were collected in 35 months of underpass monitoring. Expected frequencies were developedfrom three independent models: radio telemetry, pellet counts, and habitat-suitability indices. The null model showved that species responded to underpasses differently. In the presence of human activity carnivores were less likely to utse tinderpasses than were ungulates. Apart from hbtman act-ivity, carnivore performance ratios were better correlated to landscape variables, and ungulate performance ratios were better correlated to structural variables. We suggest that future underpasses designed around topography, habitat quality, and location will be minimally successful if human activity is not managed. | View Paper |
| Benefits and Consequences For Local Communities | Clevenger, A.P., Ford, A.T., & Sawaya, M.A. 2009. Banff Wildlife Crossings Project: Integrating Science and Education in Restoring Population Connectivity Across Transportation Corridors. | In 12 years of monitoring, researchers have detected wildlife using these crossing structures more than 185,000 times. Among the findings: • Grizzly bears are making increasing use of the new crossing opportunities. The number of recorded grizzly bear crossings has soared 35-fold, from five instances in 1996 to 177 in 2008. As a proportion of all wildlife crossings, grizzly bear use went from one of every 2000 crossings to a little more than one in 100 crossings. • Use by other species has fluctuated. Elk usage declined by 45 percent as a proportion of all crossings during the period, while deer use of the crossing structures has increased dramatically from 45 percent to over 70 percent in a 10-year period. Banff Wildlife Crossings Project, 2005–2009 Executive Summary • Several unique or unexpected observations of species using the Banff wildlife crossing structures have been made. For instance, red fox, striped skunk and hoary marmot have each been detected using the structures. The presence of boreal toads has been recorded on Wolverine overpass, garter snakes were seen at Duthil wildlife underpass, and beavers were detected using the Redearth Creek underpass. These detections have been aided by the use of remote infrared-operated cameras. • There also have been noteworthy species—primarily moose, wolverine and lynx— detected using the crossing structures less frequently than most large mammals. Current information on the moose population suggests that there are few localized individuals in the middle and lower Bow Valley. Wolverines were detected four times using three different crossing structures. Lynx were detected twice using two crossing structures. To our knowledge, these are the first detections of wolverine and lynx using wildlife crossings in North America. • We found that the presence or absence of an alpha female wolf makes a significant difference in how wolves use the crossing structures. The number of recorded through passages by wolves decreased 13 percent in the month after the mortality of a putative alpha female wolf, despite there being more attempted crossing events during this time than during the month before the mortality. We also found that wolves were more hesitant to use the crossing structures after the mortality event. The number of crossing events where wolves hesitated increased threefold following the death of the alpha female. • In looking at the relative use by wolves, cougars and coyotes, we found that there was a very low probability of any of these three species being detected at the same wildlife crossing structure during the same time interval. This supports the hypothesis that the three conspecifics avoid each other. Interestingly, when they were detected during the same monitoring check interval, coyotes were almost twice as likely to be detected with wolves as with cougars. Cougars and wolves rarely co-occurred at the crossing structures. That cougars and wolves appeared to avoid using the same crossings suggests that interspecies interactions may be a more important factor in determining species use of wildlife crossings than we have previously thought. | View Paper |
| Species Richness | Coffin, Alisa. (2007). From roadkill to road ecology: A review of the ecological effects of roads. Journal of Transport Geography. 15. 396-406. 10.1016/j.jtrangeo.2006.11.006. | Transportation infrastructure affects the structure of ecosystems, the dynamics of ecosystem function, and has direct effects on ecosystem components, including their species composition. Clearly, the construction of transport lines results in the direct destruction and removal of existing ecosystems, and the reconfiguration of local landforms. However, transportation systems, and more specifically, roads, have a wide variety of primary, or direct, ecological effects as well as secondary, or indirect, ecological effects on the landscapes that they penetrate. The effects of roads can be measured in both abiotic and biotic components of terrestrial and aquatic ecosystems. The nature of road systems as network structures renders vast areas of the landscape as road-affected, with small patches of isolated habitat remaining beyond the ecological influence of roads. The increasing attention of scientists to the unintended ecological effects of roads has resulted in the emergence of the science of “Road Ecology,” marked with the publication of a multi-authored volume, Road Ecology: Science and Solutions, in 2003. | View Paper |
| Species Movement and Dispersal | Collinge, S. K. (1996). Ecological consequences of habitat fragmentation: implications for landscape architecture and planning. Landscape and urban planning, 36(1), 59-77. | Habitat loss and isolation associated with land conversion for human activities constitute the most serious threat to the Earth's biological diversity. The study of habitat fragmentation provides an important link between the concepts and principles of landscape ecology and the practice of landscape architecture and planning. Here I review ecological literature to examine current understanding of the ecological consequences of habitat fragmentation, and briefly suggest ways in which the results of these studies may guide decision-making by landscape architects and planners. Two theoretical developments in ecology have informed studies of habitat fragmentation and have provided testable hypotheses for empirical studies: island biogeography theory and metapopulation dynamics. Ecologists have examined the influences of habitat fragment size, shape, degree of isolation, context, and habitat quality or heterogeneity on plant and animal population persistence, community composition, and ecosystem processes. Disruption of continuous habitat usually results in an increase in the length of the boundary between fragments and their surrounding habitats. Newly created edges experience shifts in microclimatic characteristics, which may significantly alter the native plant and animal communities present. The size of a habitat fragment markedly influences the ecological processes occurring therein, largely due to the changes induced by these habitat edges. In general, species richness declines as fragment area decreases. Vegetated corridors may facilitate the movement of plants and animals among habitat fragments, however, more information is needed regarding the efficacy of corridors in reducing species loss from fragmented habitats. Fragments with highly irregular, convoluted boundaries will likely have greater exchange of nutrients, materials, and organisms with adjacent habitats than will those with less convoluted boundaries. Adjacent habitat types, land management regimes, and intensity of human activities influence boundary permeability and thus flow among habitat fragments. Large fragments are likely to be more heterogeneous than small fragments; they contain a greater variety of soil types, greater topographic variation, and a greater number of habitat types. An integrated view of the spatial characteristics of habitat fragments and their ecological consequences improves our ability to predict the outcomes of, and to design, particular patterns of land conversion. | View Paper |
| Species Movement and Dispersal | Connolly-Newman, Hayley R. EFFECT OF COVER ON SMALL MAMMAL ABUNDANCE AND MOVEMENT THROUGH WILDLIFE UNDERPASSES | Crossing structures enable wildlife to safely cross highways by physically separating wildlife and vehicles. Most wildlife underpasses and overpasses are designed to accommodate a wide variety of species. Their suitability for individual species, however, varies by location (surrounding habitat), structure type (e.g. underpass or overpass), and dimensions (height, width, length). For some taxa, the habitat immediately adjacent to and inside an underpass or on top of an overpass is critical. For instance, small mammals, reptiles, amphibians and many invertebrates may avoid open areas because they require cover (e.g., live vegetation, tree stumps, branches, or rocks) to reduce predation risk and because of the microhabitat it provides (e.g., temperature, moisture). I investigated the effect of cover on the abundance and movements of small mammals in ten large mammal underpasses (approximately 7 m wide, 4 m high) along U.S. Hwy 93 North on the Flathead Indian Reservation, Montana. Track tubes recorded abundance of small mammals in and around 10 structures (5 control/ 5 treatment) in 2011 and 2012. I placed cover (dead tree limbs) inside half (five) of the underpasses in winter 2012 (treatment), while the remaining five underpasses served as control with no cover added. Capturemark-recapture using live traps was conducted in the fall of 2012 to record abundance and movement of small mammals in and around the underpasses. There was no statistically significant effect of cover on small mammal abundance detected by track tubes or live traps. . There was a statistically significant effect of cover on movement between the right of way and crossing structure for small mammals detected by live traps. By placing cover inside wildlife underpasses, wildlife managers can increase crossing structure use by small mammals at minimal cost. | View Paper |
| Benefits and Consequences For Local Communities | COOPLANTAR: A Brazilian Initiative to Integrate Forest Restoration with Job and Income Generation in Rural Areas - Mesquita et. al.. 2010 | The focus of this study was on the Monte Pascoal-Pau Brasil Ecological Corridor (MPPBEC) and on the effects of a local cooperative (COOPLANTAR) that restores forests and improves livelihoods. The MPPBEC is an extension of the Central Corridor, and consists of 94,000 ha of adjacent land. The area is primarily for growing eucalyptus, coffee, and papaya therefore much of the Central Corridor forest (120 km wide; 18% of original forest cover) is extremely fragmented. The large cellulose manufacturer, Veracel, has used Eucalyptus production in the MPPBEC as a steady supply of raw materials and has funded a large portion of conservation efforts in the area through COOPLANTAR. Through this cooperative, local communities play an active role in choosing which areas will be reforested. Riparian zones in river basins have been a top priority. Much of the restoration efforts have involved planting native trees on rural properties. By the end of 2009, COOPLANTAR had restored 200 ha of forest on Veracel¢'s land. These restored areas serve to connect several critical forest fragments within the Central Corridor and MPPBEC to form ~4,000 ha of continuous land. Plans for the future include planting a new nursery and getting more local community members involved | View Paper |
| Species Richness | Corbit et. al. Hedgerows as habitat corrdiors for forest herbs in central New York, USA | 1 Samples from 32 hedgerows (c.?6?m wide, with full?grown trees) in central New York included 39 forest herb taxa, comprising nearly 70% of the forest herb taxa found in adjacent forest samples. | View Paper |
| Species Richness, Genetic Variation | Corlatti, Luca & Hackländer, Klaus & Frey-Roos, Fredy. (2009). Ability of Wildlife Overpasses to Provide Connectivity and Prevent Genetic Isolation. Conservation biology : the journal of the Society for Conservation Biology. 23. 548-56. 10.1111/j.1523-1739.2008.01162.x. | We reviewed research on wildlife overpasses in the context of their genetic effectiveness to provide connectivity between population patches that have been isolated by road construction. The potential ecological consequences of such habitat fragmentation include reduction of gene flow between subpopulations and hence an increase in genetic differentiation and a decrease in genetic diversity. Among the solutions to provide connectivity between patches isolated by roads, wildlife overpasses are one of the most expensive alternatives. Despite the high costs associated with their construction, most of the studies assessing their use by wildlife remain observational, reporting evidence for passage use but few data on the number of individual crossings. Moreover, the use itself of wildlife overpasses does not appear sufficient to assess their effectiveness from a genetic viewpoint because a minimum number of individuals is required to assure gene flow between population patches and because the spatiotemporal dimension of individual movements and demographic parameters of subpopulations must be considered. So far, there is no evidence that wildlife overpasses do or do not efficiently address genetic issues. This lack of data is probably due to the fact that few mitigation efforts have implemented monitoring programs that incorporate sufficient experimental designs into pre- and postconstruction evaluation. To assess the genetic effectiveness of wildlife overpasses, long-term monitoring programs, including fieldwork and genetic analyses, are needed. | View Paper |
| Genetic Variation | Corlatti, Luca, Klaus Hacklaender, and F. R. E. D. Y. FREY-ROOS. "Ability of wildlife overpasses to provide connectivity and prevent genetic isolation." Conservation Biology 23.3 (2009): 548-556. | We reviewed research on wildlife overpasses in the context of their genetic effectiveness to provide connectivity between population patches that have been isolated by road construction. The potential ecological consequences of such habitat fragmentation include reduction of gene flow between subpopulations and hence an increase in genetic differentiation and a decrease in genetic diversity. Among the solutions to provide connectivity between patches isolated by roads, wildlife overpasses are one of the most expensive alternatives. Despite the high costs associated with their construction, most of the studies assessing their use by wildlife remain observational, reporting evidence for passage use but few data on the number of individual crossings. Moreover, the use itself of wildlife overpasses does not appear sufficient to assess their effectiveness from a genetic viewpoint because a minimum number of individuals is required to assure gene flow between population patches and because the spatiotemporal dimension of individual movements and demographic parameters of subpopulations must be considered. So far, there is no evidence that wildlife overpasses do or do not efficiently address genetic issues. This lack of data is probably due to the fact that few mitigation efforts have implemented monitoring programs that incorporate sufficient experimental designs into pre- and postconstruction evaluation. To assess the genetic effectiveness of wildlife overpasses, long-term monitoring programs, including fieldwork and genetic analyses, are needed. | View Paper |
| Species Movement and Dispersal | Cushman, S. A., K. S. McKelvey, J. Hayden, and M. K. Schwartz. 2006. Gene flow in complexlandscapes: testing multiple hypotheses with causal modeling. American Naturalist , 168,486–499. | Predicting population‐level effects of landscape change depends on identifying factors that influence population connectivity in complex landscapes. However, most putative movement corridors and barriers have not been based on empirical data. In this study, we identify factors that influence connectivity by comparing patterns of genetic similarity among 146 black bears (Ursus americanus), sampled across a 3,000‐km2 study area in northern Idaho, with 110 landscape‐resistance hypotheses. Genetic similarities were based on the pairwise percentage dissimilarity among all individuals based on nine microsatellite loci (average expected heterozygosity=0.79 heterozygosity=0.79). Landscape‐resistance hypotheses describe a range of potential relationships between movement cost and land cover, slope, elevation, roads, Euclidean distance, and a putative movement barrier. These hypotheses were divided into seven organizational models in which the influences of barriers, distance, and landscape features were statistically separated using partial Mantel tests. Only one of the competing organizational models was fully supported: patterns of genetic structure are primarily related to landscape gradients of land cover and elevation. The alternative landscape models, isolation by barriers and isolation by distance, are not supported. In this black bear population, gene flow is facilitated by contiguous forest cover at middle elevations. | View Paper |
| Invasive Species, Plant Dispersal | Damschen, E. I., Haddad, N. M., Orrock, J. L., Tewksbury, J. J., & Levey, D. J. (2006). Corridors increase plant species richness at large scales. Science (New York, N.Y.), 313(5791), 128-1286. | Habitat fragmentation is one of the largest threats to biodiversity. Landscape corridors, which are hypothesized to reduce the negative consequences of fragmentation, have become common features of ecological management plans worldwide. Despite their popularity, there is little evidence documenting the effectiveness of corridors in preserving biodiversity at large scales. Using a large-scale replicated experiment, we showed that habitat patches connected by corridors retain more native plant species than do isolated patches, that this difference increases over time, and that corridors do not promote invasion by exotic species. Our results support the use of corridors in biodiversity conservation. | View Paper |
| Species Movement and Dispersal, Ecosystem Services | Darryl Jones Vegetation structure on overpasses is critical in overcoming the road barrier effect for small birds | Gliding mammals are sensitive to habitat fragmentation that produces canopy gaps beyond their gliding capability. Specific structures (canopy?bridges and glide poles) are now commonly installed in large road construction projects to enable road crossing by threatened gliding mammals. However, these structures are being installed with limited understanding of how their design features influence their use. We conducted field testing of several design features (horizontal glide launch?beams at the top of poles; rope size and complexity in rope?bridges) using free?ranging gliding mammals, and scaled?down structures at two locations. Our aim was to identify preferred features to optimise structure use. This may confirm current designs or identify the need for refinement. We found that squirrel gliders (Petaurus norfolcensis) and sugar gliders (Petaurus breviceps) preferred a forward?pointing over a sideways?pointing glide beam. A single?rope rope?bridge was favoured over a mesh rope?bridge by sugar gliders but not squirrel gliders. No preference was shown by either species between mesh or ladder?style rope?bridges that differed in rope strand spacing. Large, permanently installed ladder or mesh rope?bridges commonly have single ropes connecting them to the adjacent forest. We investigated the use of a permanently installed 50?m long single?rope rope?bridge. Infra?red camera monitoring over 366 nights detected squirrel gliders on this bridge on 172 nights, common ringtail possums (Pseudocheirus peregrinus) on 144 nights and common brushtail possums (Trichosurus vulpecula) on 120 nights. This confirms acceptance of the single rope by a range of species and provides confidence in installing rope?bridges that may vary in rope size and complexity. | View Paper |
| Species Movement and Dispersal | Davies & Pullin Are hedgerows effective corridors between fragments of woodland habitat? An evidence-based approach | Anthropogenic modification of the countryside has resulted in much of the landscape consisting of fragments of once continuous habitat. Increasing habitat connectivity at the landscape-scale has a vital role to play in the conservation of species restricted to such remnant patches, especially as species may attempt to track zones of habitat that satisfy their niche requirements as the climate changes. Conservation policies and management strategies frequently advocate corridor creation as one approach to restore connectivity and to facilitate species movements through the landscape. Here we examine the utility of hedgerows as corridors between woodland habitat patches using rigorous systematic review methodology. Systematic searching yielded 26 studies which satisfied the review inclusion criteria. The empirical evidence currently available is insufficient to evaluate the effectiveness of hedgerow corridors as a conservation tool to promote the population viability of woodland fauna. However, the studies did provide anecdotal evidence of positive local population effects and indicated that some species use hedgerows as movement conduits. More replicated and controlled field investigations or long-term monitoring are required in order to allow practitioners and policy makers to make better informed decisions about hedgerow corridor creation and preservation. The benefits of such corridors in regard to increasing habitat connectivity remain equivocal, and the role of corridors in mitigating the effects of climate change at the landscape-scale is even less well understood. | View Paper |
| Population Abundance | De Lima, M. G., & Gascon, C. (1999). The conservation value of linear forest remnants in central Amazonia. Biological Conservation, 91(2-3), 241-247. | Riparian forest is protected under federal legislation in Brazil. In the Amazon Basin, numerous streams and rivers provide huge potential for increasing the conservation value of deforested and fragmented landscapes through the protection of linear remnants along watercourses. However, the potential of such remnants to be used as faunal habitat and possibly as movement corridors has never been fully investigated. We surveyed small mammal and litter-frog communities in linear remnants of primary rainforest ranging from 140 to 190 m in width, and in adjacent continuous rainforest, to compare their species richness, composition, and abundance. No significant differences were found in any aspect of community structure or species abundance. This suggests that linear remnants along watercourses provide suitable habitat for at least some forest vertebrates, a conclusion reinforced by the fact that many frogs and small mammals were found reproducing and moving in the remnants. These results highlight the potential of linear remnants to serve as habitat for small forest vertebrates and suggest they could function as corridors for some species to increase landscape connectivity. | View Paper |
| Species Richness | Derugin, V., Silveira, J., Golet, G., & LeBuhn, G. (2015). Response of medium- and large-sized terrestrial fauna to corridor restoration along the middle Sacramento River. Restoration Ecology, 24. | A fundamental challenge in restoration ecology is to understand when species are expected to colonize newly created habitat. Determining this is important for assessing progress toward restoration goals and, more generally, for gaining insight into ecosystem functioning and dynamics. We studied this question as it relates to mid? to large?sized terrestrial fauna in restored riparian habitats at the Sacramento River National Wildlife Refuge, in northern California. We used camera traps to document use of 16 riparian corridor sites of varying restoration age. Comparisons of species richness (diversity) and visitation frequency (activity) were made across different?aged sites. We found that predator diversity and activity levels tended to be higher in restored forests than in remnant forests, and that they tended to be highest in young restored forests. This trend persisted when data from variable sampling periods were pooled, although significant differences occurred more often in wet and cold sampling periods. The trend did not always hold for the animal community at large (consisting of both predator and non?predator species). We conclude that restoration age affects predator diversity and activity levels in restored and remnant floodplain forests, and that predator communities can establish soon after restoration. Our results suggest that restoring natural river processes that promote habitat regeneration may benefit mid? to large?sized terrestrial predators that appear to mostly use early successional habitat. | View Paper |
| Benefits and Consequences For Local Communities | Dettman The Mesoamerican Biological Corridor in Panama and Costa Rica | The Mesoamerican Biological Corridor (MBC) is one of the largest bioregional conservation programs in the world. The core idea behind this program is the creation of a series of protected wildlife corridors stretching from southern Mexico to eastern Panama to protect over 769,000 km2 of land. The MBC funds and oversees local projects in the corridor region that preserve biodiversity and encourage economic development. While the program should be lauded for uniting environmental decision-makers from eight countries, the implementation of the program at the local level has not been effective. One of the greatest shortcomings of the program is the lack of communication between locally-based projects and regional planning departments. Through analysis of the decision process that MBC regional managers undertake, I suggest ways in which managers could become more "problem-oriented." Effective and clearer communication of high-level goals, renewed emphasis on biodiversity preservation, creation of reliable baseline ecological data, promotion of longer tenure for resource managers, local involvement with higher level planning, and defined land use prescriptions are steps necessary for the MBC achieve its goals across Central America. | View Paper |
| Species Movement and Dispersal | Dmowski, Michal Kozakiewicz Influence of a shrub corridor on movements of passerine birds to a lake littoral zone | A pine forest was separated from a lake littoral zone by a meadow on one area (discontinuous) while these habitats were separated by a shrub strip in another area (continuous). This shrub strip acted as an ecological corridor enhancing the movements of birds between the forest and the littoral reed zone. The number of individuals of non-littoral species that visited the reed zone was higher (p < .001) on the area with the connecting shrub strip in autumn but the number of species visiting the littoral zone was not significantly higher. Significantly more (p < .001) autumn movements by birds in the continuous area were oriented along paths between the forest and the littoral zone whereas movements in the discontinuous area paralleled the littoral and forest zones (p < .001). Movements of birds were concentrated along the edge of the shrub strip. The spatial configuration of the landscape facilitated access by some forest birds to the littoral habitat. | View Paper |
| Population Abundance | Dobson, Andrew & Hilty, Jodi & Lidicker, William & Merenlender, Adina. (2007). Corridor Ecology: The Science and Practice of Linking Landscapes for Biodiversity Conservation. Bibliovault OAI Repository, the University of Chicago Press. | Corridor Ecology presents guidelines that combine conservation science and practical experience for maintaining, enhancing, and creating connectivity between natural areas with an overarching goal of conserving biodiversity. It offers an objective, carefully interpreted review of the issues and is a one-of-a-kind resource for scientists, landscape architects, planners, land managers, decision-makers, and all those working to protect and restore landscapes and species diversity. | View Paper |
| Population Abundance, Species Richness, Species Movement and Dispersal | Dodd Jr., C.K., Barichivish, W.J., & Smith, L.L. 2003. Effectiveness of a barrier wall and culverts in reducing wildlife mortality on a heavily traveled highway in Florida. Biological Conservation, 118(5), 619-631. doi: | Because of high numbers of animals killed on Paynes Prairie State Preserve, Alachua County, Florida, the Florida Department of Transportation constructed a barrier wall-culvert system to reduce wildlife mortality yet. al.low for passage of some animals across the highway. During a one year study following construction, we counted only 158 animals, excluding hylid treefrogs, killed in the same area where 2411 road kills were recorded in the 12 months prior to the construction of the barrier wall-culvert system. Within the survey area lying directly in Paynes Prairie basin, mortality was reduced 65% if hylid treefrogs are included, and 93.5% with hylid treefrogs excluded. Sixty-four percent of the wildlife kills observed along the barrier wall-culvert system occurred at a maintenance road access point and along 300 m of type-A fence bordering private property. The 24 h kill rate during the post-construction survey was 4.9 compared with 13.5 during the pre-construction survey. We counted 1891 dead vertebrates within the entire area surveyed, including the ecotone between the surrounding uplands and prairie basin which did not include the barrier wall and culverts. Approximately 73% of the nonhylid road kills occurred in the 400 m section of road beyond the extent of the barrier wall-culvert system. We detected 51 vertebrate species, including 9 fish, using the 8 culverts after the construction of the barrier wall-culvert system, compared with 28 vertebrate species in the 4 existing culverts prior to construction. Capture success in culverts increased 10-fold from the pre-construction survey to the post-construction survey. Barrier wall trespass was facilitated by overhanging vegetation, maintenance road access, and by the use of the type-A fence. Additional problems resulted from siltation, water holes, and human access. These problems could be corrected using design modifications and by routine, periodic maintenance. | View Paper |
| Ecosystem Services | Dosskey, M., Schultz, D., & Isenhart, T. (1997). Riparian Buffers for Agricultural Land. Agroforestry Notes, 3. | • Define what a riparian buffer is • Describe what benefits a riparian buffer can provide in an agricultural landscape • Identify situations where installing a riparian buffer should be considered | View Paper |
| Invasive Species | Doty, L. (2019, January 9). Levins Model—Population Dynamics. Ecology Center. | The objectives of the model are: To understand the basic concepts and dynamics of metapopulation and population stability with the help of mathematical models. To study how parameters c and e affect the population dynamics. To understand how the initial number of patches occupied in a system affect the local extinction after n years. | View Paper |
| Ecosystem Services | Durham, S. (2004). Riparian Buffers Effective. Southeast Farm Press. | Restored riparian wetland buffers retained or removed at least 60 percent of the nitrogen and 65 percent of the phosphorus that entered from an adjacent site where manure was applied, according to results of a nine-year study by Agricultural Research Service scientists in Tifton, Ga., and cooperators at the University of Georgia. | View Paper |
| Species Movement and Dispersal | Ecosystem Services. (n.d.). National Wildlife Federation. Retrieved April 27, 2020, from https://www.nwf.org/Home/Educational-Resources/Wildlife-Guide/Understanding-Conservation/Ecosystem-Services | Wildlife is important to the heritage, culture, and heart of America, and we want to preserve it as a legacy for our children. Although you cannot put a value on all the ways the natural world enriches our lives, there are many tangible benefits to living in a world with strong and healthy ecosystems. We have a stronger economy, diverse food products, and advancements in medical research as a result of wildlife and natural ecosystems. | View Paper |
| Species Movement and Dispersal | Eggers, Britta 1 ; Matern, Andrea; Drees, Claudia; Eggers, Jan; HAeRDTLE, WERNER; Assmann, Thorsten Value of Semi-Open Corridors for Simultaneously Connecting Open and Wooded Habitats: a Case Study with Ground Beetles | The value of nature to people has long been recognized, but in recent years, the concept of ecosystem services has been developed to describe these various benefits. An ecosystem service is any positive benefit that wildlife or ecosystems provide to people. The benefits can be direct or indirect—small or large. | View Paper |
| Species Movement and Dispersal, Species Richness | Elliot et. al.. Effects of a Purpose-Built Underpass on Wildlife Activity and Traffic-Related Mortality in Southern California: The Harbor Boulevard Wildlife Underpass | Conservationists have advocated the construction of wildlife crossing structures for the purpose of reducing traffic mortality of wildlife and maintaining habitat connectivity in increasingly fragmented landscapes. In May 2006, construction was completed on a wildlife underpass beneath Harbor Boulevard, a four-lane road that bisects the Puente Hills, one of the few remaining large tracts of coastal sage scrub habitat in southern Los Angeles County. We monitored the frequency of road-killed wildlife and the activity of medium and large mammals at track-stations in the vicinity of the underpass before, during and after underpass construction. We also used digital remote cameras and track stations to determine wildlife use of the new underpass. Remote cameras were installed in the underpass on 26 May 2006, soon after construction was complete. Our aim was to determine whether such underpasses reduce traffic-related mortality of wildlife and improve functional connectivity of remnant coastal sage scrub and other natural habitats for wildlife populations. Cameras indicated that wildlife began using the underpass almost immediately after construction. Mule deer and coyotes were photographed using the tunnel 3 and 4 weeks, respectively, after cameras were installed. Coyotes have used the underpass fairly regularly, with a sharp increase observed in October 2006, 23 weeks after cameras were installed. Use of the underpass by deer has been less consistent, perhaps due to seasonal changes in habitat use. As of April 2007, coyotes were photographed at the underpass an average of 26.6 times per month, and deer, an average of 2.0 times per month. Additionally, one bobcat was photographed in February 2007. Track-station surveys indicated that coyotes and striped skunks are very common across the study area, but that other rare or more secretive carnivores such as long-tailed weasels, gray foxes and bobcats are also present. Track-station activity, and the diversity of species represented, was especially high in the center of the Puente Hills study area, suggesting that wildlife activity increases as one moves east and away from more intensely urbanized areas of the county. Across the study area, rodents were the most common road-killed animals followed by, in order of abundance, striped skunks, opossums, coyotes, brush rabbits, raccoons, mule deer, and bobcats. One American badger, a species that is considered uncommon in developed parts of Los Angeles County, was also found. Incidence of road-kills increased with higher speed limits. On Harbor Boulevard, coyotes accounted for 39% of the 31 road-kills detected since surveys began in July 2004, followed by opossums (19%) and striped skunks (16%). Two bobcats (6%) were also killed by vehicles on Harbor Boulevard over this period. Incidence of road-kills was very high on Harbor Boulevard relative to the rest of the study area prior to construction; however, to date (10 months post-construction), there has been no reduction in the frequency of road-kills on Harbor Boulevard. There also has been no apparent change in the frequency of road-kills across the study area between comparable pre- and post-construction surveys. Although wildlife use of the underpass has been relatively high, the lack of any decrease in the number of road-killed animals, notably coyotes, suggests that some animals have not found or are not using the underpass, and that other measures such as fencing might be considered in the vicinity to funnel more crossings off of Harbor Boulevard and into the underpass. The underpass was constructed at Harbor Boulevard because it represents an area of significant narrowing of the Puente Hills Wildlife Corridor by urban development, where traffic-related mortality of wildlife was suspected to be high. As such, the new underpass has the potential to facilitate movement between protected areas of the Puente Hills and other undeveloped private and public lands to the east. We hope that our project, which will monitor wildlife activity and traffic-related mortality in the vicinity of the underpass through May 2007, will add to the current body of knowledge on mitigating the negative effects of roads on wildlife. Additionally, our project may also provide information that will help to eventually create and maintain a functional wildlife corridor from the San Gabriel River to the Cleveland National Forest, of which the habitat in Puente Hills will be a critical link. | View Paper |
| Species Movement and Dispersal, Ecosystem Services, Benefits and Consequences For Local Communities | Espinosa, Víctor & Aguilera-Benavente, Francisco & Delgado, Montserrat. (2019). Green infrastructure design using GIS and spatial analysis: a proposal for the Henares Corridor (Madrid-Guadalajara, Spain). Landscape Research. 45. 1-18. 10.1080/01426397.2019.1569221. | Since the late twentieth century, the concept of green infrastructure (GI) has gained increasing recognition as a valuable approach to spatial planning. Although GI is an eminently spatial element, there are still few instances where this type of infrastructure has been given explicit definition and delimitation. It is therefore necessary to develop methods capable of defining these infrastructures through explicit spatial suitability analysis of their component dimensions. Here, we present a methodology based on the use of Geographic Information Systems (GIS) to identify and map potential areas for inclusion in a GI in the Henares Corridor (Madrid-Guadalajara, Spain). We analysed four factors (the contribution to ecosystem services, ecological connectivity, ecological status, and proximity/potential accessibility to the public), combined using multi-criteria evaluation techniques, thus offering different alternatives for defining and designing GI. The GI maps obtained show better results in less restrictive situations, which could be considered to articulate the existing protected areas. | View Paper |
| Plant Dispersal | Evans et. al. Habitat patch shape, not corridors, determines herbivory and fruit production of an annual plant | Habitat corridors confer many conservation benefits by increasing movement of organisms between habitat patches, but the benefits for some species may exact costs for others. For example, corridors may increase the abundance of consumers in a habitat to the detriment of the species they consume. In this study we assessed the impact of corridors on insect herbivory of a native plant, Solanum americanum, in large-scale, experimentally fragmented landscapes. We quantified leaf herbivory and assessed fruit production as a proxy for plant fitness. We also conducted field surveys of grasshoppers (Orthoptera), a group of abundant, generalist herbivores that feed on S. americanum, and we used exclosure cages to explicitly link grasshopper herbivory to fruit production of individual S. americanum. The presence of corridors did not increase herbivory or decrease plant fruit production. Likewise, corridors did not increase grasshopper abundance. Instead, patches in our landscapes with the least amount of edge habitat and the greatest amount of warmer "core" area had the highest levels of herbivory, the largest cost to plant fruit production as a result of herbivory, and the most grasshoppers. Thus habitat quality, governed by patch shape, can be more important than connectivity for determining levels of herbivory and the impact of herbivory on plant fitness in fragmented landscapes. | View Paper |
| Species Movement and Dispersal | Fagan, M. E., DeFries, R. S., Sesnie, S. E., Arroyo-Mora, J. P., & Chazdon, R. L. (2016).Targeted reforestation could reverse declines in connectivity for understory birds in atropical habitat corridor. Ecological Applications , 26 (5), 1456–1474. | Re-establishing connectivity between protected areas isolated by habitat clearing is a key conservation goal in the humid tropics. In northeastern Costa Rica, payments for environmental services (PES) and a government ban on deforestation have subsidized forest protection and reforestation in the San Juan La Selva Biological Corridor (SJLSBC), resulting in a decline in mature forest loss and the expansion of tree plantations. We use field studies and graph models to assess how conservation efforts have altered functional connectivity over the last 25 years for four species of insectivorous understory birds. Field playback studies assessed how reforestation habitat quality affected the willingness of Myrmeciza exsul, Henicorhina leucosticta, Thamnophilus atrinucha, and Glyphorynchus spirurus to travel outside forest habitat for territorial defense. Observed travel distances were greatest in nonnative and native tree plantations with high understory stem density, regardless of overstory composition. In contrast, tree plantations with low stem density had travel responses comparable to open pasture for three of the four bird species. We modeled landscape connectivity for each species using graph models based on varying possible travel distances in tree plantations, gallery forests, and pastures. From 1986 to 2011, connectivity for all species declined in the SJLSBC landscape (5825 km2) by 14% to 21% despite only a 4.9% net loss in forest area and the rapid expansion of tree plantations over 2% of the landscape. Plantation placement in the landscape limited their potential facilitation of connectivity because they were located either far from forest cover or within already contiguous forest areas. We mapped current connectivity bottlenecks and identified priority areas for future reforestation. We estimate that reforestation of priority areas could improve connectivity by 2% with only a 1% gain in forest cover, an impressive gain given the small area reforested. Results indicate key locations where spatial targeting of PES within the SJLSBC study region would protect existing forest connectivity and enhance the connectivity benefits of reforestation. | View Paper |
| Species Richness | Fahrig, Lenore & Rytwinski, Trina. (2009). Effects of Roads on Animal Abundance: an Empirical Review and Synthesis. Ecology and Society. 14. 10.5751/ES-02815-140121. | We attempted a complete review of the empirical literature on effects of roads and traffic on animal abundance and distribution. We found 79 studies, with results for 131 species and 30 species groups. Overall, the number of documented negative effects of roads on animal abundance outnumbered the number of positive effects by a factor of 5; 114 responses were negative, 22 were positive, and 56 showed no effect. Amphibians and reptiles tended to show negative effects. Birds showed mainly negative or no effects, with a few positive effects for some small birds and for vultures. Small mammals generally showed either positive effects or no effect, mid-sized mammals showed either negative effects or no effect, and large mammals showed predominantly negative effects. We synthesized this information, along with information on species attributes, to develop a set of predictions of the conditions that lead to negative or positive effects or no effect of roads on animal abundance. Four species types are predicted to respond negatively to roads: (i) species that are attracted to roads and are unable to avoid individual cars; (ii) species with large movement ranges, low reproductive rates, and low natural densities; and (iii and iv) small animals whose populations are not limited by road-affected predators and either (a) avoid habitat near roads due to traffic disturbance or (b) show no avoidance of roads or traffic disturbance and are unable to avoid oncoming cars. Two species types are predicted to respond positively to roads: (i) species that are attracted to roads for an important resource (e.g., food) and are able to avoid oncoming cars, and (ii) species that do not avoid traffic disturbance but do avoid roads, and whose main predators show negative population-level responses to roads. Other conditions lead to weak or non-existent effects of roads and traffic on animal abundance. We identify areas where further research is needed, but we also argue that the evidence for population- level effects of roads and traffic is already strong enough to merit routine consideration of mitigation of these effects in all road construction and maintenance projects. | View Paper |
| Population Abundance | Fahrig, L. (2003). Effects of habitat fragmentation on biodiversity. Annual review of ecology, evolution, and systematics, 34(1), 487-515. | The literature on effects of habitat fragmentation on biodiversity is huge. It is also very diverse, with different authors measuring fragmentation in different ways and, as a consequence, drawing different conclusions regarding both the magnitude and direction of its effects. Habitat fragmentation is usually defined as a landscape-scale process involving both habitat loss and the breaking apart of habitat. Results of empirical studies of habitat fragmentation are often difficult to interpret because (a) many researchers measure fragmentation at the patch scale, not the landscape scale and (b) most researchers measure fragmentation in ways that do not distinguish between habitat loss and habitat fragmentation per se, i.e., the breaking apart of habitat after controlling for habitat loss. Empirical studies to date suggest that habitat loss has large, consistently negative effects on biodiversity. Habitat fragmentation per se has much weaker effects on biodiversity that are at least as likely to be positive as negative. Therefore, to correctly interpret the influence of habitat fragmentation on biodiversity, the effects of these two components of fragmentation must be measured independently. More studies of the independent effects of habitat loss and fragmentation per se are needed to determine the factors that lead to positive versus negative effects of fragmentation per se. I suggest that the term "fragmentation" should be reserved for the breaking apart of habitat, independent of habitat loss. | View Paper |
| Species Movement and Dispersal, Ecosystem Services | Fan, Zhenggen; Pan, Jiasen; Ding, Dengwei; Yu, Jiang Study on the Construction of Ecological Drainage Pipe with Critter Crossing Function | Critter pasage can to a large extent ensure the safety of living things crossing the road and reduce the traffic mortality of living things arising from crossing the road. Outdoor drainage pipes can eliminate accumulated surface water, alleviate the drainage pressure of urban roads, and reduce the phenomenon of urban stagnant water. At present, there are many studies on the construction methods of drainage pipes, and there are also many studies on critter pasage, but there is little research on the organic combination of critter pasage and drainage pipes. Taking the drainage pipe as the research object, in accordance with the basic requirements of critter pasage, this paper studies the construction methods of ecological drainage pipe with critter pasage function, in order to solve the problem of single function of drainage pipe at present. It can provide a reference for related research in the future. | View Paper |
| Population Abundance | Farmer, Kay H. "A.P.E.S.". Apesportal.Eva.Mpg.De, 2011, | View Paper | |
| Species Richness, Population Abundance | Fernanda Zimmermann TeixeiraI; Rodrigo Cambará Printes; Joo Cláudio Godoy Fagundes; André Chein Alonso; Andreas KindelI | The effects of habitat fragmentation and deforestation are exacerbated by some elements, such as roads and power lines, which may become filters or barriers to wildlife movements. In order to mitigate mortality and restore connectivity, wildlife passages are being constructed as linear corridors. The installation of these mitigation measures must be followed by systematic monitoring, in order to evaluate their use and effectiveness, to assist in their management, and to convince stakeholders of their value. In this paper we present the results of a monitoring study of the use of rope overpasses developed near a protected area in Porto Alegre, southern Brazil. The canopy bridges were installed by the Urban Monkeys Program in places where electric hazards and road-kills of brown howler monkeys (Alouatta guariba clamitans Cabrera, 1940) were recorded. Camera traps were installed at each bridge, and local people were selected and trained to monitor overpass use over 15 months, from August 2008 to October 2009. Three species were recorded using canopy bridges: brown howler monkey (Alouatta guariba clamitans Cabrera, 1940), white-eared opossum (Didelphis albiventris Lund, 1840) and porcupine (Sphiggurus villosus Cuvier, 1823). Rope bridges with the highest number of species recorded had more forest cover and lower urban area around them than overpasses little used. Our results indicate that overpasses, in Porto Alegre, work as a linear corridor between forest remnants, although the outcomes for individual survival, group persistence, population demography or gene flow have not been measured. Furthermore, canopy bridges may be important to mitigate the impact of roads and power lines on wildlife, but electric cables also need to be completely isolated when present, to warrant animals' physical integrity. | View Paper |
| Species Movement and Dispersal | Ferraz, G. G., G. J. Russell, P. C. Stouffer, R. O. Bierregaard, S. L. Pimm, and T. E. Lovejoy.2003. Rates of species loss from Amazonian forest fragments. Proceedings of theNational Academy of Sciences of the USA , 100, 14069–14073. | In the face of worldwide habitat fragmentation, managers need to devise a time frame for action. We ask how fast do understory bird species disappear from experimentally isolated plots in the Biological Dynamics of Forest Fragments Project, central Amazon, Brazil. Our data consist of mist-net records obtained over a period of 13 years in 11 sites of 1, 10, and 100 hectares. The numbers of captures per species per unit time, analyzed under different simplifying assumptions, reveal a set of species-loss curves. From those declining numbers, we derive a scaling rule for the time it takes to lose half the species in a fragment as a function of its area. A 10-fold decrease in the rate of species loss requires a 1,000-fold increase in area. Fragments of 100 hectares lose one half of their species in <15 years, too short a time for implementing conservation measures. | View Paper |
| Ecosystem Services | Fischer, R. A., Martin, C. O., & Fischenich, J. C. (2000). Improving Riparian Buffer Strips and Corridors for Water Quality and Wildlife. American Water Resources Association. | The management and restoration of riparian zones has received considerable attention throughout the United States. Numerous studies have shown that riparian buffer strips of sufficient width protect and improve water quality by intercepting non-point source pollutants. Buffer strips also clearly provide a diversity of other functions, including movement corridors and habitat for a large variety of organisms. However, criteria for determining proper dimensions of buffer strips for most ecological functions are not well established. Although riparian zones are being restored along thousands of streambank miles throughout the country, the ecological benefits of variable buffer strip designs (e.g., width, length, vegetation type, placement within the watershed) have not been adequately recognized. There have been few systematic attempts to establish criteria that mesh water quality width requirements with other riparian functions. Subsequently, management prescriptions (e.g., width recommendations) are frequently based upon anecdotal information with little regard for the full range of effects these decisions may have on other riparian functions. Our objectives are to address the suitability of riparian zones to protect water quality while enhancing biodiversity, and to discuss recent strides in providing improved guidance for corridor and buffer designs based primarily on ecological criteria | View Paper |
| Species Movement and Dispersal | Forman, R. T. T. & Alexander, L. E. 1998. Roads and their major ecological effects. Annual Review of Ecology and Systematics, 29, 207-231. | A huge road network with vehicles ramifies across the land, representing a sur‚prising frontier of ecology. Species-rich roadsides are conduits for few species. Roadkills are a premier mortality source, yet ex:cept for local spots, rates rarely limit population size. Road avoidance, especially due to traffic noise, hasa greater ecological impact. The still-more-importantbarrier effect subdivides populations, with demographic and probably genetic consequences. Road networks crossing landscapes cause local hydrologic and erosion effects, whereas stream networks and distant valleys receive major peak-flow and sediment impacts. Chemical ef‚fects mainly occur near roads. Road networks interrupt horizontal ecological flows, alter landscape spatial pattern, and therefore inhibit important interior species. Thus, road density and network structure are informative landscape ecology assays. Australia has huge road-reserve networks of native vegetation, whereas the Dutch have tunnels and overpasses perforating road barriers to en‚hance ecological flows. Based on road-effect zones, an estimated 15-20% of the United States is ecologically impacted by roads. | View Paper |
| Genetic Variation | Frankham, Richard. "Genetic rescue of small inbred populations: Meta-analysis reveals large and consistent benefits of gene flow." Molecular ecology 24.11 (2015): 2610-2618. | Many species have fragmented distribution with small isolated populations suffering inbreeding depression and/or reduced ability to evolve. Without gene flow from another population within the species (genetic rescue), these populations are likely to be extirpated. However, there have been only ~ 20 published cases of such outcrossing for conservation purposes, probably a very low proportion of populations that would potentially benefit. As one impediment to genetic rescues is the lack of an overview of the magnitude and consistency of genetic rescue effects in wild species, I carried out a meta-analysis. Outcrossing of inbred populations resulted in beneficial effects in 92.9% of 156 cases screened as having a low risk of outbreeding depression. The median increase in composite fitness (combined fecundity and survival) following outcrossing was 148% in stressful environments and 45% in benign ones. Fitness benefits also increased significantly with maternal ΔF (reduction in inbreeding coefficient due to gene flow) and for naturally outbreeding versus inbreeding species. However, benefits did not differ significantly among invertebrates, vertebrates and plants. Evolutionary potential for fitness characters in inbred populations also benefited from gene flow. There are no scientific impediments to the widespread use of outcrossing to genetically rescue inbred populations of naturally outbreeding species, provided potential crosses have a low risk of outbreeding depression. I provide revised guidelines for the management of genetic rescue attempts. | View Paper |
| Genetic Variation | Frankham, Richard. "Genetics and extinction." Biological Conservation 126 (2005): 131-140. | The role of genetic factors in extinction has been a controversial issue, especially since Lande's paper [Genetics and demography in biological conservation, Science 241 (1988) 1455-1460] paper in Science. Here I review the evidence on the contribution of genetic factors to extinction risk. Inbreeding depression, loss of genetic diversity and mutation accumulation have been hypothesised to increase extinction risk. There is now compelling evidence that inbreeding depression and loss of genetic diversity increase extinction risk in laboratory populations of naturally outbreeding species. There is now clear evidence for inbreeding depression in wild species of naturally outbreeding species and strong grounds from individual case studies and from computer projections for believing that this contributes to extinction risk. Further, most species are not driven to extinction before genetic factors have time to impact. The contributions of mutation accumulation to extinction risk in threatened taxa appear to be small and to require very many generations. Thus, there is now sufficient evidence to regard the controversies regarding the contribution of genetic factors to extinction risk as resolved. If genetic factors are ignored, extinction risk will be underestimated and inappropriate recovery strategies may be used. | View Paper |
| Species Movement and Dispersal | Gang Zhou, Shegang Shao, Xiaomin Wu, Yufeng Zhu, Hongfeng Zhang, Zhaoming Wang Evaluation on Utilization Effect of Highway Wildlife Corridor in Desert and Gobi Area | Taking the design of wildlife corridor from Mingshui to Hami section of national expressway from Beijing to Urumqi as an example. From January 2015 to May 2018, the project team monitored and studied the wildlife utilization of 13 corridors along the route from Mingshui to Hami. The results show that wildlife along the highway has begun to use Bridges, culverts and passageways to cross the highway. | View Paper |
| Species Movement and Dispersal | Garci, S., & Akay, A. E. Assessment of ecological passages along road networks within the Mediterranean forest using GIS-based multi criteria evaluation approach. Environmental monitoring and assessment, 187(12), 779. | Major roads cause barrier effect and fragmentation on wildlife habitats that are suitable places for feeding, mating, socializing, and hiding. Due to wildlife collisions (Wc), human-wildlife conflicts result in lost lives and loss of biodiversity. Geographical information system (GIS)-based multi criteria evaluation (MCE) methods have been successfully used in short-term planning of road networks considering wild animals. Recently, wildlife passages have been effectively utilized as road engineering structures provide quick and certain solutions for traffic safety and wildlife conservation problems. GIS-based MCE methods provide decision makers with optimum location for ecological passages based on habitat suitability models (HSMs) that classify the areas based on ecological requirements of target species. In this study, ecological passages along Motorway 52 within forested areas in Mediterranean city of Osmaniye in Turkey were evaluated. Firstly, HSM coupled with nine eco-geographic decision variables were developed based on ecological requirements of roe deer (Capreolus capreolus) that were chosen as target species. Then specified decision variables were evaluated using GIS-based weighted linear combination (WLC) method to estimate movement corridors and mitigation points along the motorway. In the solution process, two linkage nodes were evaluated for eco-passages which were determined based on the least-cost movement corridor intersecting with the motorway. One of the passages was identified as a natural wildlife overpass while the other was suggested as underpass construction. The results indicated that computer-based models provide accurate and quick solutions for positioning ecological passages to reduce environmental effects of road networks on wild animals. | View Paper |
| Species Richness | Garcia-Gonzalez, Claudia & Campo, Daniel & Pola, Ivan & Garcia-Vazquez, Eva. (2012). Rural road networks as barriers to gene flow for amphibians: Species-dependent mitigation by traffic calming. Landscape and Urban Planning - LANDSCAPE URBAN PLAN. 10.1016/j.landurbplan.2011.10.012. | Population structuring based on mitochondrial DNA variation along the rural landscape of the Trubia val-ley in North Iberia revealed significant association between road density and genetic distance between populations of two amphibian species, the midwife toad Alytes obstetricans and the palmate newt Lissotri-ton helveticus. Traffic calming (concentration of flows on minor rural roads at a few highways to decrease volumes and speeds) near urban settlements mitigates the population fragmentation of L. helveticus butnot that of A. obstetricans, indicating that even small roads with low-intensity traffic act as barriers for the latter species. We suggest that the construction of passages for amphibians across rural roads would potentially mitigate population fragmentation of endangered species like the anuran A. obstetricans. | View Paper |
| Species Richness | Gilbert, F., A. Gonzalez, and I. Evans-Freke, Corridors maintain species richness in the fragmented landscapes of a microecosystem. Proceedings of the Royal Society of London. Series B: Biological Sciences, 1998. 265(1396): p. 577-582. | Theory predicts that species richness or single-species populations can be maintained, or at least extinctions minimized, by boosting rates of immigration. One possible way of achieving this is by establishing corridors of suitable habitat between reserves. Using moss patches as model microecosystems, we provide here probably the first field experimental test of the idea that corridors can reduce the rate of loss of species, and therefore help to maintain species richness. Connecting patches of habitat with corridors did indeed slow the rate of extinction of species, preserving species richness for longer periods of time than in disconnected habitat patches. The pattern of biodiversity, the cumulative species richness of entire connected systems, is similarly higher than that of fragmented systems, despite the homogenizing effects of movement. Predators are predicted to be more susceptible to fragmentation because of their greater mobility and smaller population sizes. Our data are consistent with this prediction: the proportion of predator species declined significantly in disconnected as compared with connected treatments. | View Paper |
| Species Movement and Dispersal, Invasive Species | Gilbert-Norton, L., Wilson, R., Stevens, J. R., & Beard, K. H. (2010). A meta-analytic review of corridor effectiveness. Conservation Biology: The Journal of the Society for Conservation Biology, 24(3), 660-668. | Using corridors for conservation is increasing despite a lack of consensus on their efficacy. Specifically, whether corridors increase movement of plants and animals between habitat fragments has been addressed on a case-by-case basis with mixed results. Because of the growing number of well-designed experiments that have addressed this question, we conducted a meta-analysis to determine whether corridors increase movement; whether corridor effectiveness differs among taxa; how recent changes in experimental design have influenced findings; and whether corridor effectiveness differs between manipulative and natural experiments. To conduct our meta-analysis, we analyzed 78 experiments from 35 studies using a conservative hierarchical Bayesian model that accounts for hierarchical and sampling dependence. We found a highly significant result that corridors increase movement between habitat patches by approximately 50% compared to patches that are not connected with corridors. We found that corridors were more important for the movement of invertebrates, nonavian vertebrates, and plants than they were for birds. Recent methodological advances in corridor experiments, such as controlling for the area added by corridors, did not influence whether corridors increased movement, whereas controlling for the distance between source and connected or unconnected recipient patches decreased movement through corridors. After controlling for taxa differences and whether studies controlled for distance in experimental design, we found that natural corridors (those existing in landscapes prior to the study) showed more movement than manipulated corridors (those created and maintained for the study). Our results suggest that existing corridors increase species movement in fragmented landscapes and that efforts spent on maintaining and creating corridors are worthwhile. | View Paper |
| Species Richness | Glista, David & DeVault, Travis & DeWoody, J.. (2009). A review of mitigation measures for reducing wildlife mortality on roadways. Landscape and Urban Planning. 91. 1-7. 10.1016/j.landurbplan.2008.11.001. | A growing literature in the field of road ecology suggests that vehicle/wildlife collisions are important to biologists and transportation officials alike. Roads can affect the quality and quantity of available wildlife habitat, most notably through fragmentation. Likewise, vehicular traffic on roads can be direct sources of wildlife mortality and in some instances, can be catastrophic to populations. Thus, connectivity of habitat and permeability of road systems are important factors to consider when developing road mortality mitigation systems. There are a variety of approaches that can be used to reduce the effects of roads and road mortality on wildlife populations. Here, we briefly review wildlife-crossing structures, summarize previous wildlife road mortality mitigation studies, describe common mitigation measures, and discuss factors that influence the overall effectiveness of mitigation strategies. Because there are very few road mortality studies “before” and “after” the installation of wildlife-crossing structures, their efficiency is nearly impossible to evaluate. However, simple and relatively inexpensive measures reviewed herein can almost certainly reduce the number of collisions between wildlife and automobiles. | View Paper |
| Species Movement and Dispersal | Gloyne, C. C., & Clevenger, A. P. (2001). Cougar Puma concolor use of wildlife crossingstructures on the Trans-Canada highway in Banff National Park, Alberta. WildlifeBiology , 7 (3), 117–124. | Large carnivores are vulnerable to road effects because of their great mobility and extensive spatial requirements for survival. Wildlife crossing structures have mitigated harmful effects of roads for ungulate species, but there is limited information on how effective these structures are for large predators. We investigated the response of cougars Puma concolor to wildlife crossing structures along 45 kilometers of the Trans-Canada highway in Banff National Park, Alberta, Canada. Twenty-two crossing structures were monitored year-round for wildlife passage during 1996-2000. Cougar consistently used the wildlife crossing structures more than expected during winter months and less than expected during the summer. There was a significant positive correlation between passages made by cougar through wildlife crossing structures and those made by mule deer Odocoileus hemionus and white-tailed deer O. virginianus. There was no correlation between cougar and human use of the wildlife crossing structures. Cougar use of the five structure types differed from that expected. Open-span bridge underpasses were used more than expected, whereas creek bridge underpasses were used in proportion to their availability. All other crossing structure types were used significantly less than expected. The wildlife crossing structures that received the highest numbers of cougar passages were those situated close to high quality cougar habitat. The pattern of structure use was partly explained by the quality and distribution of cougar habitat near the structures as opposed to their physical features. Our results indicated that cougars tended to use underpasses more than wildlife overpass structures, and our study documents that cougars used crossing structures in a way that ensures habitat connectivity. | View Paper |
| Species Movement and Dispersal | Goldingay, Taylor, Parkyn Can field trials improve the design of road?crossing structures for gliding mammals? | Gliding mammals are sensitive to habitat fragmentation that produces canopy gaps beyond their gliding capability. Specific structures (canopy?bridges and glide poles) are now commonly installed in large road construction projects to enable road crossing by threatened gliding mammals. However, these structures are being installed with limited understanding of how their design features influence their use. We conducted field testing of several design features (horizontal glide launch?beams at the top of poles; rope size and complexity in rope?bridges) using free?ranging gliding mammals, and scaled?down structures at two locations. Our aim was to identify preferred features to optimise structure use. This may confirm current designs or identify the need for refinement. We found that squirrel gliders (Petaurus norfolcensis) and sugar gliders (Petaurus breviceps) preferred a forward?pointing over a sideways?pointing glide beam. A single?rope rope?bridge was favoured over a mesh rope?bridge by sugar gliders but not squirrel gliders. No preference was shown by either species between mesh or ladder?style rope?bridges that differed in rope strand spacing. Large, permanently installed ladder or mesh rope?bridges commonly have single ropes connecting them to the adjacent forest. We investigated the use of a permanently installed 50?m long single?rope rope?bridge. Infra?red camera monitoring over 366 nights detected squirrel gliders on this bridge on 172 nights, common ringtail possums (Pseudocheirus peregrinus) on 144 nights and common brushtail possums (Trichosurus vulpecula) on 120 nights. This confirms acceptance of the single rope by a range of species and provides confidence in installing rope?bridges that may vary in rope size and complexity. | View Paper |
| Species Movement and Dispersal, Species Richness | Goosem, M., Weston, N., & Bushnell, S. (2005). Effectiveness of rope bridge arboreal overpasses and faunal underpasses in providing connectivity for rainforest fauna. UC Davis. | Rope bridge overpasses and faunal underpasses were effective in restoring rainforest habitat connectivity for many tropical rainforest species that suffer high levels of road mortality or that avoid large clearings, such as those for roads, and, therefore, suffer barrier effects. Faunal underpasses furnished with logs and rocks to provide cover were constructed in 2001 at a hotspot for tree-kangaroo mortality. The narrow road and 120-m-wide strip of abandoned pasture divided two blocks of rainforest severing an important highland wildlife corridor through an agricultural landscape. No rainforest small mammals were recorded crossing the gap in six months of trapping prior to the road upgrade. During the upgrade, corridors of rainforest trees were planted through the pasture to connect with underpass entrances. Underpass use was monitored weekly using sand tracking beds complemented by infrared-triggered digital cameras. Weekly road kill data were collected for 12 months prior to construction and continues on two 0.5-km road transects in the vicinity of the underpasses and two transects along a highway dividing similar rainforest habitat 5km to the north. In 2004, bird and small mammal use of the planted corridors was investigated. Many terrestrial rainforest species use the underpasses, including medium-sized and smaller mammals and terrestrial birds, together with two confirmed passages of the rare target species, Lumholtz's tree-kangaroo. Road mortality near the underpasses has remained low, whereas road kill rates are much greater along the narrow rainforest highway without underpasses. Community composition of rainforest birds within the corridors is approaching that of edge rainforest nearby, demonstrating effectiveness at this early stage of growth. However, although rainforest small mammals reside in the corridors, feral and pasture species still dominate, emphasizing the need for longer growth periods to encourage greater use by rainforest specialist mammals of the connectivity afforded by corridors and underpasses. Several rope bridges erected 7m above narrow roads and designed for use by rare arboreal rainforest mammals have also proven effective and are regularly used by the obligate arboreal Lemuroid ringtail possum, which will not cross roads on the surface or via underpasses. Several other possums that rarely venture to ground level are also regular crossers. Structures also provide safe crossing routes for arboreal species that otherwise suffer road mortality. Monitoring using active infrared-triggered cameras, scat and hair collection, and spotlighting has shown all target rainforest ringtails and other possums using rope tunnel and cheaper rope ladder designs. Similar designs have since been installed elsewhere in Australia over four-lane highways. Subsequent rainforest studies will investigate use of longer rope bridges above a wide highway using mark-recapture and radio-tracking to determine home range and provide population information prior to construction, followed by systematic monitoring of the rope bridges. | View Paper |
| Species Movement and Dispersal | Goran Gunvica et. al. Comparative Analysis of Three Different Methods for Monitoring the Use of Green Bridges by Wildlife | Green bridges are used to decrease highly negative impact of roads/highways on wildlife populations and their effectiveness is evaluated by various monitoring methods. Based on the 3-year monitoring of four Croatian green bridges, we compared the effectiveness of three indirect monitoring methods: track-pads, camera traps and active infrared (IR) trail monitoring system. The ability of the methods to detect different species and to give good estimation of number of animal crossings was analyzed. The accuracy of species detection by track-pad method was influenced by granulometric composition of track-pad material, with the best results obtained with higher percentage of silt and clay. We compared the species composition determined by track-pad and camera trap methods and found that monitoring by tracks underestimated the ratio of small canids, while camera traps underestimated the ratio of roe deer. Regarding total number of recorder events, active IR detectors recorded from 11 to 19 times more events then camera traps and app. 80% of them were not caused by animal crossings. Camera trap method underestimated the real number of total events. Therefore, an algorithm for filtration of the IR dataset was developed for approximation of the real number of crossings. Presented results are valuable for future monitoring of wildlife crossings in Croatia and elsewhere, since advantages and disadvantages of used monitoring methods are shown. In conclusion, different methods should be chosen/combined depending on the aims of the particular monitoring study. | View Paper |
| Benefits and Consequences For Local Communities | Governing REDD+: global framings versus practical evidence from the Kasigau Corridor REDD+ Project, Kenya - Atela, 2013 | The Kasigau Corridor built by Wildlife Works is 500,000 acres and links Tsavo East and Tsavo West National Parks, the two largest wildlife protection areas in Kenya. These parks contribute significant revenue to Kenya's GDP through eco-tourism. Kasigau is the first project to issue carbon credits under the international system of Voluntary Carbon Standards (VCS) and the Climate Community and Biodiversity Standard (CCBS). This has allowed for a shift away from traditional practices such as hunting for game meat, cropping, and harvesting wood products. The tourism industry has led to an increase in human-wildlife conflict, as communities resist being totally cut off from subsistence resources. However, with the introduction of the REDD+ framework, local people are beginning to have more favorable attitudes towards conservation efforts. The Kasigau corridor project has been so successful largely because the project developers (Wildlife Works) have worked in the area since 1998 and so have long-standing relationships with the community. The area chief and other community leaders were told about the project long before any work got under way, and communication traveled largely through traditional cultural means such as chiefs' barazas (meetings), to avoid top-down dictation. The community was included and engaged in all phases of development. While attitudes are favorable at present, the continued success of the Kasigau project will hinge on navigating through the complicated political waters of land rights and use. | View Paper |
| Species Movement and Dispersal | Green, S. E., Davidson, Z., Kaaria, T., & Doncaster, C. P. (2018). Do wildlife corridors link or extend habitat? Insights from elephant use of a Kenyan wildlife corridor. African Journal of Ecology. | Human encroachment on wildlife habitats is leading to increased fragmentation; hence, there is an increasing focus on improving connectivity between remaining habitat. Large, wide‐ranging species such as the African elephant, (Loxodonta africana), are particularly vulnerable due to their extensive habitat requirements. Wildlife corridors have been created to facilitate movement, with little knowledge to date on whether they serve their intended function as transit routes, or whether they simply extend the available habitat for occupancy. We collected data on elephant behaviour in the Mount Kenya Elephant Corridor, with the aim of quantifying the utility of the corridor. A grid of 25 camera traps was used to survey the 478 ha corridor over 11 weeks. Cameras recorded over 43,000 photos with 694 separate events triggered by elephants. Patterns of use varied spatially and temporally, indicating that certain areas were treated as habitat extension, while others were predominantly for transit. These differences were likely due to variation in vegetation cover and levels of human disturbance. Corridor use differed amongst individuals, suggesting that use may depend on both the characteristics of the corridor itself and the social or resource needs of individual elephants. | View Paper |
| Species Movement and Dispersal | GURRUTXAGA, M., & SAURA, S. (2014). Prioritizing highway defragmentation locations for restoring landscape connectivity. Environmental Conservation, 41(2), 157-164. doi:10.1017/S0376892913000325 | This study evaluated the effectiveness of highway defragmentation in maintaining the passages of wildlife, upholding the importance of such defragmentation in ensuring continuity of habitat corridors. | View Paper |
| Species Movement and Dispersal | Gužvica, G., Bošnjak, I., Bielen, A., Babić, D., Radanović-Gužvica, B., & Šver, L. (2014).Comparative analysis of three different methods for monitoring the use of green bridgesby wildlife. PLoS ONE , 9(8). | Green bridges are used to decrease highly negative impact of roads/highways on wildlife populations and their effectiveness is evaluated by various monitoring methods. Based on the 3-year monitoring of four Croatian green bridges, we compared the effectiveness of three indirect monitoring methods: track-pads, camera traps and active infrared (IR) trail monitoring system. The ability of the methods to detect different species and to give good estimation of number of animal crossings was analyzed. The accuracy of species detection by track-pad method was influenced by granulometric composition of track-pad material, with the best results obtained with higher percentage of silt and clay. We compared the species composition determined by track-pad and camera trap methods and found that monitoring by tracks underestimated the ratio of small canids, while camera traps underestimated the ratio of roe deer. Regarding total number of recorder events, active IR detectors recorded from 11 to 19 times more events then camera traps and app. 80% of them were not caused by animal crossings. Camera trap method underestimated the real number of total events. Therefore, an algorithm for filtration of the IR dataset was developed for approximation of the real number of crossings. Presented results are valuable for future monitoring of wildlife crossings in Croatia and elsewhere, since advantages and disadvantages of used monitoring methods are shown. In conclusion, different methods should be chosen/combined depending on the aims of the particular monitoring study. | View Paper |
| Species Movement and Dispersal | H.-J. Mader, Animal habitat isolation by roads and agricultural fields, Biological Conservation, Volume 29, Issue 1, 1984, Pages 81-96, ISSN 0006-3207. | Natural areas are continuously disappearing. Surviving patches resemble islands in terms of limited area, isolation and distance from each other. Road construction and agricultural activities contribute to habitat isolation. Field studies suggest that roads represent barriers and cut off the gene flow by dividing animal populations into fractions on either side of the road. Several mobility diagrams show significant isolation effects of roads on populations of forest-dwelling mice (Apodemus flavicollis) and carabid beetles. Small habitat islands tend to hold more animal species than expected according to the island biogeographic theory. The NsNi ratio is highest in small isolates, indicating continuous movement of individual animals from surrounding agricultural areas resulting in unstable species composition. | View Paper |
| Species Movement and Dispersal | Haas, C. A. (1995). Dispersal and use of corridors by birds in wooded patches on an agricultural landscape. Conservation biology, 9(4), 845-854 | Dispersal behavior has important effects on the persistence and recolonization of populations, but is one of the least understood traits of most organisms. Knowledge of patterns of fledgling, natal, and breeding dispersal of birds in a patchy environment will assist in decisions regarding reserve design and protection or construction of corridors. I present data on movement patterns of three migratory bird species, American Robin ( Turdus migratorius ), Brown Thrasher ( Toxostoma rufum ), and Loggerhead Shrike ( Lanius ludovicianus). These birds are relatively common breeders in south-central North Dakota (US) in riparian woodlands and in shelterbelts (woodlots planted as windbreaks in the open agricultural environment). Field assistants and I individually marked and monitored the movements of more than 500 adults breeding in a network of shelterbelts across an 8 — 11 km study area. Most movement occurred at relatively short distances within a shelterbelt. Movements by adults between shelterbelt sites, although rare, occurred significantly more frequently between sites connected by a wooded corridor than between unconnected sites. For robins, there were on average 2.5 dispersal events between each pair of connected sites, but only 0.17 dispersal events between each pair of unconnected sites (Mann-Whitney test, significant at p<0.009). Because unconnected and connected sites were similar in average area (1.7 to 1.9 ha), distance to next wooded habitat, and tree-species composition, this result provides a test of the hypothesis that organisms disperse preferentially along connecting corridors. | View Paper |
| Invasive Species | Haddad et. al. CORRIDOR AND DISTANCE EFFECTS ON INTERPATCH MOVEMENTS: A LANDSCAPE EXPERIMENT WITH BUTTERFLIES | The hypothesis that corridors increase animal movement between habitat fragments, a central tenet of conservation biology, has been virtually untested. This study demonstrates that corridors increase interpatch movement rates of two butterfly species. The hypothesis was tested in a large?scale, replicated experiment, in which 27 equal?sized (1.64?ha) patches of early successional habitat were created within large areas of pine forest. Patches varied in whether or not they were connected to another patch by a corridor, and in their distance from other patches (64x384 m). The results of mark-release-recapture studies showed that two open habitat butterfly species, Junonia coenia and Euptoieta claudia, moved more frequently between patches connected by corridors than between unconnected patches. Interpatch movement was significantly, negatively related to interpatch distance. Interpatch movement rates of J. coenia were significantly, positively related to the density of its host and nectar resource, Linaria canadensis. Corridor effects were stronger for males than for females and were most pronounced within three days after butterflies were marked. Pine forest was not a complete barrier to butterfly movement; both species moved between unconnected patches, even at the longest distances. However, the results of this study suggest that corridors will increase long?distance movements of habitat?restricted species. | View Paper |
| Species Movement and Dispersal | Haddad et. al. Corridor Use Predicted from Behaviors at Habitat Boundaries | Through empirical studies and simulation, I demonstrate how simple behaviors can be used in lieu of detailed dispersal studies to predict the effects of corridors on interpatch movements. Move- ment paths of three butterfly species were measured in large (1.64 ha) experimental patches of open habitat, some of which were con- nected by corridors. Butterflies that "reflected" off boundaries be- tween open patches and the surrounding forest also emigrated from patches through corridors at rates higher than expected from random movement. This was observed for two open-habitat species, Eurema nicippe and Phoebis sennae; however, edges and corridors had no effect on a habitat generalist, Papilio troilus. Behaviorally based sim- ulation models, which departed from correlated random walks only at habitat boundaries, predicted that corridors increase interpatch movement rates of both open-habitat species. Models also predicted that corridors have proportionately greater effects as corridor width increases, that movement rates increase before leveling off as corridor width increases, and that corridor effects decrease as patch size in- creases. This study suggests that corridors direct movements of hab- itat-restricted species and that local behaviors may be used to predict the conservation potential of corridors in fragmented landscapes. | View Paper |
| Population Abundance | Haddad, N. M., & Baum, K. A. (1999). An experimental test of corridor effects on butterfly densities. Ecological Applications, 9(2), 623-633. | In a large-scale experiment, we found that three habitat-restricted butterfly species reached higher densities in patches connected by corridors than in similar, isolated patches. We conducted our study in 27 equal-sized (1.64-ha) patches that varied in whether or not they were connected to another patch by a corridor. Patches and corridors were open, early=successional habitat that contrasted strongly with the surrounding pine forest. Of four butterfly species studied, three open-habitat specialists (Junonia coenia, Euptoieta claudia, and Phoebis sennae) reached higher densities in patches connected by corridors than in isolated patches. A fourth species, Papilio troilus, showed no preference for open habitat or pine forest, and its density did not differ in connected or isolated patches. Although butterfly densities were often significantly, positively associated with densities of host plant or flower resources, plant densities did not confound corridor effects on butterfly densities. Higher densities in patches connected by corridors may have been caused by three different factors. First, species with higher densities in connected patches also moved more frequently between connected patches, and higher movement rates may have helped to sustain higher population sizes. Second, species with higher densities in connected patches also had higher densities farther from the forest edge. Corridors increased the area of a patch that was farther from the forest edge, which increased the "effective area" of connected patches and may have increased butterfly densities. Third, corridors may have acted as "drift fences" intercepting dispersers from the surrounding forest and directing them to connected patches. We could not determine the relative contribution of each factor, and it is possible that all three contributed to higher densities of habitat-restricted butterflies in patches connected by corridors. | View Paper |
| Species Movement and Dispersal, Species Richness | Haddad, N. M., Bowne, D. R., Cunningham, A., Danielson, B. J., Levey, D. J., Sargent, S., & Spira, T. (2003). Corridor use by diverse taxa. Ecology, 84(3), 609-615. doi:10.1890/0012-9658(2003)084[0609:CUBDT]2.0.CO;2 | One of the most popular approaches for maintaining populations and conserving biodiversity in fragmented landscapes is to retain or create corridors that connect otherwise isolated habitat patches. Working in large-scale, experimental landscapes in which open-habitat patches and corridors were created by harvesting pine forest, we showed that corridors direct movements of different types of species, including butter?ies, small mammals, and bird-dispersed plants, causing higher movement between connected than between unconnected patches. Corridors directed the movement of all 10 species studied, with all corridor effect sizes .68%. However, this corridor effect was signi?cant for ?ve species, not signi?cant for one species, and inconclusive for four species because of small sample sizes. Although we found no evidence that corridors increase emigration from a patch, our results show that movements of disparate taxa with broadly different life histories and functional roles are directed by corridors. | View Paper |
| Invasive Species | HADDAD, N. M., BRUDVIG, L. A., DAMSCHEN, E. I., EVANS, D. M., JOHNSON, B. L., LEVEY, D. J., WELDON, A. J. (2014). Potential Negative Ecological Effects of Corridors. Conservation Biology, 28(5), 1178-1187. | Despite many studies showing that landscape corridors increase dispersal and species richness for disparate taxa, concerns persist that corridors can have unintended negative effects. In particular, some of the same mechanisms that underlie positive effects of corridors on species of conservation interest may also increase the spread and impact of antagonistic species (e.g., predators and pathogens), foster negative effects of edges, increase invasion by exotic species, increase the spread of unwanted disturbances such as fire, or increase population synchrony and thus reduce persistence. We conducted a literature review and meta-analysis to evaluate the prevalence of each of these negative effects. We found no evidence that corridors increase unwanted disturbance or non-native species invasion; however, these have not been well-studied concerns (1 and 6 studies, respectively). Other effects of corridors were more often studied and yielded inconsistent results; mean effect sizes were indistinguishable from zero. The effect of edges on abundances of target species was as likely to be positive as negative. Corridors were as likely to have no effect on antagonists or population synchrony as they were to increase those negative effects. We found 3 deficiencies in the literature. First, despite studies on how corridors affect predators, there are few studies of related consequences for prey population size and persistence. Second, properly designed studies of negative corridor effects are needed in natural corridors at scales larger than those achievable in experimental systems. Third, studies are needed to test more targeted hypotheses about when corridor-mediated effects on invasive species or disturbance may be negative for species of management concern. Overall, we found no overarching support for concerns that construction and maintenance of habitat corridors may result in unintended negative consequences. Negative edge effects may be mitigated by widening corridors or softening edges between corridors and the matrix. Other negative effects are relatively small and manageable compared with the large positive effects of facilitating dispersal and increasing diversity of native species. | View Paper |
| Species Movement and Dispersal | Hamer, A. J., Van der Ree, R., Mahony, M. J., & Langton, T. Usage rates of an under-road tunnel by three Australian frog species: implications for road mitigation, 17(4), 379-387. | Many amphibians in Europe and North America regularly use under-road tunnels during dispersal. However, such structures have not been shown to mitigate the impacts of road mortality on frog populations in Australia. We tested the behavioural response of three Australian frog species to a 12-m amphibian under-road tunnel in controlled ex situ conditions. In April and October 2012, we tested 34 striped marsh frogs Limnodynastes peronii, 54 green and golden bell frogs Litoria aurea, and 15 broad-palmed frogs Lit. latopalmata. The overall proportion of frogs entering the tunnel (tunnel usage), and entering and exiting the tunnel at the opposite end (tunnel efficiency), among the three species was 0.13 and 0.05, respectively. The proportion of usage for Lim. peronii, Lit. aurea and Lit. latopalmata was 0.21, 0.07 and 0.13, respectively. The mean time taken for an individual to enter the tunnel was 14-min 22-s. There was some evidence of directionality in the movement of Lim. peronii and Lit. aurea within the experimental arena. Tunnel usage was not likely related to air temperature, humidity or light levels inside the tunnel, but requires further investigation. Our study showed that there was low usage of the under-road tunnel compared with the relatively high usage rates of tunnels by amphibians in the Northern Hemisphere. Our results demonstrate that the effectiveness of wildlife tunnels in mitigating the impact of roads on frog species in Australia and tropical regions requires further investigation. We recommend testing these tunnels once installed under several roads near wetlands to assess how frogs respond to them during the breeding period. | View Paper |
| Species Movement and Dispersal | Hanski, I. (1998) Metapopulation dynamics. Nature 396, 41–49. | View Paper | |
| Genetic Variation | Haponski, A.E. and Stepien, C.A. Genetic connectivity and diversity of walleye (Sander vitreus) spawning groups in the Huron-Erie Corridor. | The Huron-Erie Corridor (HEC) The Huron “Erie Corridor (HEC) connects the upper and lower Great Lakes, providing key fish passage. A cen-tury of channelization, dredging, and pollution has led to habitat loss and declining fish numbers. Since 2004, the multi-agency HEC initiative augmented fish spawning habitat at Belle Isle and Fighting Island in the Detroit River, whose populations are examined here. We analyze genetic patterns among seven spawning groups (N = 311) of walleye Sander vitreus, a key fishery species, using nine nuclear DNA microsatellite loci and mitochondrial DNA control region sequences. Results reveal that all spawning groups contained appre-ciable genetic diversity (microsatellites: H O = 0.72; mtDNA: H D = 0.73) and showed a mixture of connectivity and divergence. Genetic relationships did not fit an isolation by geographic distance hypothesis, with some closely spaced populations being very different. Notably, the Flint River “Lake Huron spawning group was the most divergent, showing no genetic exchange. The Belle Isle and Fighting Island populations markedly differed, with the latter showing some genetic exchange with the Grosse Ile (Detroit River) and the Huron River (northwest Lake Erie) populations to the south. Walleye spawning at Fighting Island experienced no significant change in overall genetic diversity pre-versus post-habitat augmentation, but the allelic frequency changed. Our results comprise an important baseline for future population analyses and habitat assessment of these habitat augmentation areas. Despite habitat degradation and pollution, it appears that historic walleye spawning groups have persisted along the HEC, meriting continued genetic monitoring and further restoration efforts to conserve and enhance this important and diverse fishery. | View Paper |
| Invasive Species | Harris, Ian & Mills, Harriet & Bencini, Roberta. (2010). Multiple individual southern brown bandicoots (Isoodon obesulus fusciventer) and foxes (Vulpes vulpes) use underpasses installed at a new highway in Perth, Western Australia. CSIRO Wildlife Research. 37. 127-133. 10.1071/WR09040. | Context. Although wildlife crossing structures are often included when new roads are built, their effectiveness at reconnecting wildlife populations is still largely unknown. A new highway was built in 2005 through an area of remnant vegetation in Perth, Western Australia. Assessment of the area before construction identified potential impacts on a population of southern brown bandicoots (Isoodon obesulus fusciventer). Aims. We aimed to determine the use by bandicoots of three underpasses constructed to provide a linkage between habitats that were fragmented by the highway, focussing on how many different individuals used them, which is an essential step to demonstrate their effectiveness at reconnecting fragmented populations. Methods. We used detection of tracks in sand pads for 1 year to establish the use of the underpasses by bandicoots. We then captured 56 bandicoots and fitted them with passive integrated transponders (PIT), and installed a Trovan 650 scanner/decoder within the most frequently used underpass to establish whether multiple individuals used it. Key results. By using sand pads, we demonstrated that bandicoots used the underpasses, with a total of 278 passes between August 2005 and August 2006. One underpass accounted for 71% of these passes and was used already during construction. Eight different bandicoots were recorded using this underpass between August 2006 and August 2007, demonstrating use by multiple individuals. A dramatic decline in the use of this underpass was observed after foxes (Vulpes vulpes) also started using it in August 2006, and a fox built a den near the entrance of this structure. Because we also failed to recapture any of the bandicoots implanted with PITs we suspect that they had been killed by foxes. Conclusions. A severe decline in bandicoots coinciding with underpass use by foxes raises questions as to the long-term success of fauna crossings. Clearly, the relationship between underpass use by predators and the target species, in this case bandicoots, needs to be examined further. Implications. Our work demonstrated that although underpasses have the potential to reconnect populations because multiple individuals used them, their installation may be detrimental to wildlife populations if predators are not controlled. | View Paper |
| Population Abundance | Harrison, R., Wardell-Johnson, G., & McAlpine, C. (2003). Rainforest Reforestation and biodiversity benefits: a case study from the Australian Wet Tropics. Annals of Tropical Research, 25(2), 65-76. | This paper examines the effectiveness of a rainforest reforestation program (the Community Rainforest Reforestation Program in north-eastern Queensland, Australia) in providing amenity and biodiversity benefits. This program involved small areas of mainly mixed native timber species on private farmland. Government support was provided for the program, for both timber production and environmental reasons. Survey results reveal that landholders have planted trees, and intend to manage plantations, for diverse reasons, including conservation purposes. The plantings appear to be of environmental value, forming wildlife corridors and buffer areas. In this respect, the CRRP has achieved a limited success in meeting the implicit goal of biological conservation. | View Paper |
| Species Richness | Harrison, S. & Bruna, E. (1999). Habitat fragmentation and large-scale conservation: what do we know for sure? Ecography, 22, 225-232. | Habitat fragmentation has been a central preoccupation in conservation biology since the field began. One reason for this is that fragmentation is occurring to natural habitats throughout the world; the other is that ecologists have felt they had something to offer in terms of understanding and mitigating its effects. MaeArthur and Wilson's (1967) theory of island biogeography was the iirst to offer the prospect that an elegant and general ecological model could lead to a powerful set of conservation prescriptions. Although island biogeography has faded from the scene somewhat, the hope of a general understanding of fragmentation lives on, as evidenced by a continued proliferation of models oi" fragmented habitats. At the same time, a growing number of empirical studies have examined how ecological processes of all kinds are altered when continuous habitats are turned into sets of isolated remnants. The literature on fragmentation grows ever richer, yet we still lack a synthesis between general principles and consistent field evidence. In this brief and opinionated essay, we will not attempt such a synthesis, but we will address three related questions: First, what ecological theories are being applied to habitat fragmentation, and how have they contributed to our understanding? Second, what do and don't we know about the ecological effects of habitat fragmentation based on existing empirical evidence? And finally. are we arriving at any general conclusions about fragmentation, and what are our most significant unanswered questions? | View Paper |
| Species Richness | Hawes, J., et. al.., The value of forest strips for understorey birds in an Amazonian plantation landscape. Biological Conservation, 2008. 141(9): p. 2262-2278. | Remnant forest strips are frequently proposed as valuable conservation tools in fragmented tropical landscapes, yet we currently lack evidence to evaluate their potential conservation value for native biota. We examined the potential value for understorey forest birds of 30-year-old riparian and‚ terra firme‚ (unflooded) primary forest strips within a large silvicultural landscape in the north-east Brazilian Amazon, where the matrix is dominated by Eucalyptus plantations. We conducted mist-netting in eight forest strips connected to continuous forest (four of each forest type), with a total of 24 replicate sampling sites located near to (<1‚ km), far from (2.5-9-km), and within undisturbed forest controls (i.e. 16 samples within the strips, and 8 in controls). Bird communities in both strip types changed with increasing distance along forest remnants into the plantation matrix. Matrix-embedded samples were characterised by a higher representation of birds typical of secondary growth forest but not those typical of the Eucalyptus-dominated matrix. While the long-term viability of the bird populations in these remnants remains unclear, our data demonstrate that forest strips can provide important habitat for many bird species that are otherwise rarely found outside primary forest. Forest strips therefore provide an important tool to enhance biodiversity conservation in plantation landscapes. The relative practical ease with which these areas can be selected and maintained means that the protection of forest strips as part of a wider conservation strategy is likely to have particular appeal to policy makers and landscape managers working in the human-dominated tropics. | View Paper |
| Influencing Animal Behavoir | Hein, C. D., Castleberry, S. B., & Miller, K. V. (2008). Sex-specific summer roost-site selection by seminole bats in response to landscape-level forest management. Journal of Mammalogy, 89(4), 964-972. | Although importance of forested corridors to navigating and foraging bats has been documented, the relationship between corridors and roost-site selection has not been studied. From late May to mid-August 2003-2006, we used radiotelemetry to investigate roost-site selection by Seminole bats (Lasiurus seminolus) on an intensively managed landscape with forested corridors in southern South Carolina. We tracked 27 (10 males and 17 females) adult Seminole bats to 90 (41 males and 49 females) diurnal roosts. We found 61% (n‚ = 25) of male and 63% (n‚ = 31) of female roosts in forested corridors, which comprised 11% of the landscape. We modeled roost-site selection with logistic regression and used Akaike's information criterion for small samples (AICc) and Akaike weights to select models relating roost-site selection to landscape-level features. Our results indicated that several factors (i.e., distance to nearest corridor and distance to nearest mature pine stand) influenced roost-site selection and that differences existed between males and females, and among female reproductive condition. Examination of our data suggests that landscape-level features are more important than tree- and plot-level characteristics for roosting by Seminole bats on this managed forest. Corridors may represent a feasible approach to maintaining suitable roosting habitat for Seminole bats in managed forest landscapes. | View Paper |
| Influencing Animal Behavoir | Hein, C. D., Miller, K. V., & Castleberry, S. B. (2009). Evening bat summer roost-site selection on a managed pine landscape. Journal of Wildlife Management, 73(4), 511-517. | Creation and maintenance of forested corridors to increase landscape heterogeneity has been practiced for decades but is a new concept in intensively managed southern pine (Pinus spp.) forests. Additionally, more information is needed on bat ecology within such forest systems. Therefore, we examined summer roost-site selection by evening bats (Nycticeius humeralis) in an intensively managed landscape with forested corridors in southeastern South Carolina, USA, 2003-2006. We radiotracked 53 (26 M, 27 F) adult evening bats to 75 (31 M, 44 F) diurnal roosts. We modeled landscape-level roost-site selection with logistic regression and evaluated models using Akaike's Information Criterion for small samples. Model selection results indicated that mature (‰¥40 yr) mixed pine-hardwood stands were important roost sites for male and lactating female evening bats. Upland forested corridors, comprised of mature pine or mixed pine-hardwoods, were important roosting habitats for males and, to a lesser extent, lactating females. Male roosts were farther from open stands and lactating female roosts were farther from mid-rotation stands than randomly selected structures. Our results suggest roost structures (i.e., large trees and snags) in mature forests are important habitat components for evening bats. We recommend maintaining older (>40 yr old) stand conditions in the form of forest stands or corridors across managed landscapes to provide roosting habitat. Furthermore, our results suggest that an understanding of sex-specific roost-site selection is critical for developing comprehensive guidelines for creating and maintaining habitat features beneficial to forest bats. | View Paper |
| Invasive Species, Species Movement and Dispersal | Hess, George R. “Conservation Corridors and Contagious Disease: A Cautionary Note.” Conservation Biology, vol. 8, no. 1, 1994, pp. 256–262. JSTOR, www.jstor.org/stable/2386739. Accessed 16 Apr. 2021. | Recent conservation proposals frequently include the establishment of corridors to connect isolated patches of wildlife habitat. Much attention has been focused on the potential benefits of corridors with little note given to potentially adverse consequences. A simulation model is developed here to study the effect of corridors on the survival of a metapopulation in the presence of a fatal disease that is spread by direct contact between susceptible and infected individuals. For the disease modeled here, a landscape of patches connected by corridors generally suffers fewer metapopulation extinctions than a landscape of isolated patches. However, under a narrow range of conditions, results suggest that corridors may dramatically increase the probability of metapopulation extinction. This occurs when disease-induced mortality is low enough to allow infected individuals to spread the disease, but high enough to reduce population levels to the point that random demographic and environmental events cause frequent metapopulation extinctions. This has important implications for the design and management of conservation reserve networks. Although discussion focuses primarily on conservation corridors, the model results apply to any management techniques that increase the movement of individuals among populations. | View Paper |
| Ecosystem Services | Hoctor, T. S., Allen, W. L., Carr, M. H., Zwick, P. D., Huntley, E., Smith, D. J., & Buch, R. (2008). Land Corridors in the Southeast USA: Connectivity to Protect Biodiversity and Ecosystem Services . Journal of Conservation Planning, 4, 90-122. | In this issue paper, land corridors are discussed as an integral element of regional conservation planning. Land corridors most commonly refer to landscape linkages or conservation corridors that are designed to combat impacts of habitat fragmentation (Wilcox and Murphy 1985; Harris and Scheck 1991; Noss 1993; Bennett 1999; Anderson and Jenkins 2006). Landscape linkages and conservation corridors if designed and managed properly facilitate connectivity, which maintains listed and other focal species populations (Lambeck 1997) and ecosystem services (Costanza et. al.. 1997; Daily 1997). Interconnected systems of conservation lands are often called "ecological networks" (Hoctor et. al.. 2000; Noss 2003; Jongman and Pungetti 2004; Clevenger and Wierzchowski 2006). Data, tools, and planning products for designing ecological networks are increasing and will significantly enhance efforts to achieve sustainable landscapes. Various regional conservation projects in the southeastern United States focused on protecting and restoring landscape connectivity are discussed in this paper | View Paper |
| Genetic Variation | Horskins, Kerrilee. (2005). The Effectiveness of Wildlife Corridors in Facilitating Connectivity: Assessment of a Model System from the Australian Wet Tropics. | Wildlife corridors have become a widely adopted management strategy for the conservation of species in fragmented habitats. Fragmentation reduces the size of habitat patches and increases the isolation of the populations within them, potentially resulting in extinction due to stochastic processes. The provision of a corridor between habitat patches is believed to increase the level of connectivity through the integration of populations into a single demographic unit, thus increasing the probability of survival. This assumption remains largely untested due to both a lack of investigation, and design limitations in some of the few studies performed. Connectivity is often assumed to occur simply from the presence of individuals within the corridor. Design criteria essential for the rigorous assessment of connectivity were identified and a landscape meeting these criteria selected. The vegetation within the corridor was found to be comparable in both structure and species composition to that of the patches that it connected. Two target species (Melomys cervinipes and Uromys caudimaculatus) were shown to occur along the corridor but not within the surrounding matrix. The combination of these factors indicated that the corridor was suitable for use as a model system and ensured that any subsequent results truly reflected the capacity of the corridor to function in the desired manner. The population structure was similar within the corridor and the connected patches for both species. Weights of individuals, sex ratios and the percentage of juveniles were consistent between the two system components, suggesting that the corridor contained breeding populations. Connectivity was therefore possible via generational gene flow for both species, while long distance movement events for U. caudimaculatus also indicated that direct movement between habitat patches maybe possible for this larger species. Despite all ecological parameters indicating that connectivity was likely, genetic markers (mtDNA and nDNA) revealed significant population differentiation between the connected patches for both species. Populations linked by the corridor and those in isolated habitats were found to show the same level of genetic differentiation. Sampling at a finer spatial scale within connected patches and a continuous control habitat showed that population differentiation was common for M. cervinipes. Given the continuity of suitable vegetation, and the presence of individuals of breeding age along the corridor system, this was attributed to social structuring. U. caudimaculatus populations also showed evidence of genetic differentiation within a connected patch and along the corridor, despite panmixia within the continuous habitat. Having investigated a model system, the data from this study has implications for other wildlife corridor studies and for landscape managers. Firstly, the advantages of using an integrated ecological and genetic approach have been demonstrated. While genetic data determined the level of connectivity, the ecological data provided an understanding of the processes operating within the system. Secondly, the level of scale at which wildlife corridor studies are conducted may need addressing. Most studies currently treat a fragmented landscape in a binary manner and consider the connected patch to be the finest "grain". However, the processes responsible for the lack of connectivity were found to operate at the much finer within-patch scale. Finally, this study clearly indicated that not all wildlife corridors will provide connectivity between the connected populations and that connectivity cannot be inferred from the presence of individuals within the corridor. Given that social behaviour such as territorial defence and philopatry are common in many species, especially small mammals, a lack of connectivity via a wildlife corridor may be more common than currently assumed. The successful use of wildlife corridors as a management strategy, and the accurate assessment of their effectiveness therefore requires careful consideration of not only structural attributes of the corridor, but also behavioural, demographic and genetic parameters of the target species. | View Paper |
| Species Movement and Dispersal | Huijser, M.P., Fairbank, E.R., Camel-Means, W., Graham, J., Watson, V., Basting, P., & Becker, D. 2015. Effectiveness of short sections of wildlife fencing and crossing structures along highways in reducing wildlife-vehicle collisions and providing safe crossing opportunities for large mammals. Biological Conservation, 197, 61-68. | Wildlife fencing in combination with crossing structures is commonly regarded as the most effective and robust strategy to reduce large mammal -collisions while also maintaining wildlife connectivity across roads. However, fencing and associated measures may affect landscape esthetics and are sometimes considered costly and unpopular. Therefore fence length is often minimized. We investigated 1) whether short fenced road sections were similarly effective in reducing large mammal vehicle collisions as long fenced road sections (literature review), and 2) whether fence length influenced large mammal use of underpasses (two field studies). We found that: 1) short fences (? 5 km road length) had lower (52.7%) and more variable (0-94%) effectiveness in reducing collisions than long fences (> 5 km) (typically > 80% reduction); 2) wildlife use of underpasses was highly variable, regardless of fence length (first field study); 3) most highway crossings occurred through isolated underpasses (82%) rather than at grade at fence ends (18%) (second field study); and 4) the proportional use of isolated underpasses (compared to crossings at fence ends) did not increase with longer fence lengths (up to 256 m from underpasses) (second field study). If the primary success parameter is to improve highway safety for humans by reducing collisions with large ungulates, the data suggest fence lengths of at least 5 km. While longer fence lengths do not necessarily guarantee higher wildlife use of underpasses as use varies greatly between locations, wildlife fencing can still improve wildlife use of an individual underpass. | View Paper |
| Invasive Species | Hunt, A., H.J. Dickens, and R.J. Whelan. 1987. Movement of mammals through tunnels under railway lines. Australian Zoologist 24:89-93. | Fragmentation of extensive natural ecosystems by roads, railways and other barriers poses major threats to populations of native animals. Attempts have been made to reduce the magnitude of these threats by constructing "underpasses" designed to permit exchange of animals. We compared mammal use of long-established drainage culverts and newly constructed tunnels under the Maldon-Dombarton rail line, near Wollongong, New South Wales. Small mammals used the established culverts, but use of the new tunnels was predominantly by feral predators. We predict that frequent use by small, native mammals will not occur until native vegetation regenerates around the tunnel entrances, establishing a connection between undisturbed vegetation on the two sides of the track. We also argue that follow-up studies such as this one should be an integral part of the environmental impact study of a proposed development. | View Paper |
| Species Richness | J. Michael Scott, Blair Csuti, James D. Jacobi and John E. Estes, BioScience, Species Richness, Vol. 37, No. 11 (Dec., 1987), pp. 782-788 (7 pages), Published By: Oxford University Press | View Paper | |
| Species Movement and Dispersal | J. Pander M. Mueller J. Geist, ECOLOGICAL FUNCTIONS OF FISH BYPASS CHANNELS IN STREAMS: MIGRATION CORRIDOR AND HABITAT FOR RHEOPHILIC SPECIES | The introduction of weirs into stream ecosystems resulted in modifications of serial continuity and in the decline of riverine fish species. Successful river restoration requires information on the ecological functionality of fish bypass channels that are considered an ecological improvement according to the European Water Framework Directive. In this study, we compared the functionality of three nature?oriented fish passes as compensatory habitats and migration corridors for fishes. Fish passes differed significantly from upstream and downstream reaches of the weirs, revealing higher current speed, lower water depth, smaller channel width and greater habitat variability. Following these structural differences, they provided key habitats for juvenile, small and rheophilic fishes that are typically underrepresented in highly modified water bodies. All fish passes were used as migration corridors, with increased fish movements during high discharge and at spawning periods. Because river stretches with high variability of current speed and water depth are scarce in highly modified water bodies, fish passes can play an important role as compensatory habitats and should thus be considered more intensively in habitat assessments and river restoration. Ideally, fish bypasses should mirror the natural discharge dynamics and consider all occurring fish species and sizes. | View Paper |
| Genetic Variation, Population Abundance | J.D. Dixon, M.K. Oli, M.C. Wooten, T.H. Eason, J.W. McCown & D. Paetkau Effectiveness of a Regional Corridor in Connecting Two Florida Black Bear Populations | Corridors may mitigate the adverse effects of habitat fragmentation by restoring or maintaining connectivity between disjunct populations. The efficacy of corridors for large carnivores, however, has rarely been evaluated objectively. We used noninvasive sampling, microsatellite analysis, and population assignment tests to evaluate the effectiveness of a regional corridor in connecting two Florida black bear (Ursus americanus floridanus) populations (Osceola and Ocala). Bear movement was predominantly unidirectional, with a limited mixing of individuals from the two populations in one area of the corridor. We also documented bears in Osceola that were genetically assigned to Ocala and bears in Osceola that may be offspring from an Osceola?Ocala mating. Our results indicate that the Osceola?Ocala corridor is functional and provides a conduit for gene flow between these populations. Human development, however, may hinder the use of the Osceola?Ocala corridor by bears. The noninvasive sampling and genetic methods we used provide a means of evaluating corridor effectiveness that can help identify linkages necessary for maintaining metapopulation structure and population viability. | View Paper |
| Species Movement and Dispersal | Janis Fedowick A landscape restoration framework for wildlife and agriculture in the rural landscape | Landscape restoration is increasingly becoming a necessary management directive for the rural landscape. The addition of patches and corridors in a fragmented agricultural landscape is considered to restore ecological integrity to the landscape by enhancing the biogeochemical cycle. Agricultural benefits of erosion reduction and nutrient cycling, as well as wildlife enhancements in terms of providing habitat, movement corridors, etc., can also be attained by diversifying the fragmented landscape. The challenge lies in developing a restoration method which establishes a symbiotic relationship between agriculture and wildlife. This research has developed one such method of implementing a regional landscape restoration design. The number and location of the additional patches and corridors necessary to restore the landscape were determined for a case study site in southern Ontario. Three alternative restoration designs were then generated to simulate the structural and functional changes in landscape composition. The placement of patches and corridors in the first alternative emphasizes wildlife enhancement. The second alternative emphasizes the existing grid-like pattern of the cultural features (e.g. road alignment, lot layout). The third alternative provides a compromise between maximizing either wildlife or agricultural benefits thereby emphasizing landscape functioning. | View Paper |
| Population Abundance, Species Richness | Jansen, A. (2005). Avian use of restoration plantings along a creek linking rainforest patches on the Atherton Tablelands, North Queensland. Restoration Ecology, 13(2), 275-283. | Rainforest fragmentation and creek degradation are major problems on the Atherton Tablelands in North Queensland. Lake Barrine and Wooroonooran National Parks are separated by a 1.5-km length of Toohey's Creek which has been cleared except for small remnant rainforest patches. The creek has been fenced and replanted to create a corridor between the two national parks. The aim of this study was to monitor the success of the corridor in providing habitat for rainforest birds. Avian communities were monitored in the corridor and in adjacent rainforest sites using point counts over the period of reestablishment of a continuous rainforest canopy. In terms of bird community composition, within 3 years of planting, the replanted sites were on a trajectory toward the rainforest sites. Although specialist rainforest species were not yet found in the plantings, after 3 years those species which mainly inhabit rainforest but also utilize edges and riparian strips were found in similar numbers in the plantings and in the small remnant patches along the corridor. Frugivorous species were quite abundant even in the youngest plantings. Thus, replanting of rainforest trees along Toohey's Creek has begun to provide habitat for some rainforest birds. It also shows good potential to act as a corridor to connect the previously isolated patches of rainforest for these species and to develop in habitat complexity as the frugivorous birds bring in rainforest plant species from nearby areas. | View Paper |
| Species Movement and Dispersal, Species Richness | Jensen, Alex Crossing Corridos:Wildlife use of jumpouts and undercrossings along a highway with wildlife exclusion fencing | Roads pose two central problems for wildlife: wildlife-vehicle collisions (WVCs) and habitat fragmentation. Wildlife exclusion fencing can reduce WVCs but can exacerbate fragmentation. In Chapter 1, I summarize the relevant studies addressing these two problems, with a focus on large mammals in North America. Chapters 2 and 3 summarize field assessments of technologies to reduce WVCs and maintain connectivity, specifically jumpout ramps and underpasses, along Highway 101 near San Luis Obispo, CA. In a fenced highway, some animals inevitably breach the fence and become trapped, which increases the risk of a wildlife-vehicle collision. Earthen escape ramps, or "jumpouts", can allow the trapped animal to escape the highway corridor. Few studies have quantified wildlife use of jumpouts, and none for >2 years. We used wildlife cameras to quantify wildlife use of 4 jumpouts from 2012-2017. Mule deer were 88% percent of our detections and jumped out 20% of the time. After accounting for pseudoreplication, 33% of the events were independent events, and 2 groups of deer accounted for 41% of all detections at the top of the jumpout. Female deer were 86% of the detections and were much more likely than males to return to the jumpout multiple times. This is the first study to document use of jumpouts for more than 3 years, the first to account for pseudoreplication, and the first to quantify differences in jumpout use between male and female mule deer. We recommend a jumpout height between 1.75m-2m for mule deer to increase the jumpout success rate. Chapter 3 addresses factors that may affect the use of undercrossings by mule deer and other wildlife. Wildlife crossings combined with wildlife exclusion fencing have been shown to be the most effective method to reduce wildlife-vehicle collisions while maintaining ecological connectivity. Although several studies have quantified wildlife use of undercrossings, very few have exceeded 24 months, and the factors affecting carnivores use of the undercrossings remain unclear. We quantified mule deer, black bear, mountain lion, and bobcat use of 11 undercrossings along Highway 101 near San Luis Obispo, California from 2012-2017. We constructed zero-inflated Poisson general linear models on the monthly activity of our focal species using underpass dimensionality, distance to cover, substrate, human activity, and location relative to the wildlife exclusion fence as predictor variables. We accounted for temporal variation, as well as spatial variation by quantifying the landscape resistance near each undercrossing. We found that deer almost exclusively used the larger underpasses whereas the carnivores were considerably less selective. Bears used undercrossings more that were within the wildlife exclusion fence, whereas mountain lion activity was higher outside the wildlife exclusion fence. Bobcat activity was highest and most widespread, and was negatively associated with distance to cover. Regional connectivity is most important for bear and mountain lion, and the surrounding habitat may be the most important predictor for their use of undercrossings. We recommend placing GPS collars on our focal species to more clearly document fine-scale habitat selection near the highway. | View Paper |
| Invasive Species | Johnson et. al.. Edge effects, not connectivity, determine the incidence and development of a foliar fungal plant disease | Using a model plant-pathogen system in a large-scale habitat corridor experiment, we found that corridors do not facilitate the movement of wind-dispersed plant pathogens, that connectivity of patches does not enhance levels of foliar fungal plant disease, and that edge effects are the key drivers of plant disease dynamics. Increased spread of infectious disease is often cited as a potential negative effect of habitat corridors used in conservation, but the impacts of corridors on pathogen movement have never been tested empirically. Using sweet corn (Zea mays) and southern corn leaf blight (Cochliobolus heterostrophus) as a model plant-pathogen system, we tested the impacts of connectivity and habitat fragmentation on pathogen movement and disease development at the Savannah River Site, South Carolina, USA. Over time, less edgy patches had higher proportions of diseased plants, and distance of host plants to habitat edges was the greatest determinant of disease development. Variation in average daytime temperatures provided a possible mechanism for these disease patterns. Our results show that worries over the potentially harmful effects of conservation corridors on disease dynamics are misplaced, and that, in a conservation context, many diseases can be better managed by mitigating edge effects. | View Paper |
| Population Abundance | Jones Menna E. (2000) Road upgrade, road mortality and remedial measures: impacts on a population of eastern quolls and Tasmanian devils. Wildlife Research 27, 289-296. | The impact of road mortality on local populations of wildlife has rarely been quantified. In June 1991, the access road into the northern end of the Cradle Mountain – Lake St Clair National Park in Tasmania was widened and sealed. This occurred part-way through an ecological study of the dasyurid carnivore guild, during which populations were being monitored. In 17 months, the resident population of 19 eastern quolls became extinct and the devil population, of 39 individuals, halved. Concurrently, there was a dramatic increase in the number of road-kills. The main causal factor was probably an increase in modal speed of about 20 km h–1 and a greater increase in maximum speed. Measures were implemented to reduce the incidence of vehicle/wildlife collisions. Measures directed at people included physically slowing traffic speed (using ‘slow points’) and increasing driver awareness (signs and pamphlets). Those directed at wildlife included deterring wildlife from crossing the road in the path of approaching vehicles (wildlife reflectors), and encouraging escape off the road (ramps across gutters and banks, and pipes for shelter). The ‘slow points’ were effective in reducing vehicle speeds by 20 km h–1. Wildlife used the ramps and pipes. The eastern quoll population was re-establishing within six months, and after two years, had recovered to 50% of its former level. There was some indication that devil populations were recovering. | View Paper |
| Species Richness | Jones, Darryl & Blacker, Amy. (2010). Road barrier effect on small birds removed by vegetated overpass in South East Queensland. Ecological Management & Restoration. 11. 65 - 67. 10.1111/j.1442-8903.2010.00516.x. | The ecological impacts of road networks and traffic have long been recognised although effective approaches to the mitigation of fragmentation influences have generally been minor in scale (Glista et. al.. 2009). This is changing with a dramatic increase of interest by road authorities, government agencies and consultants in the design of fauna crossing structures. Purpose-built fauna underpasses are now commonly included in plans for new roads and upgrades of existing roads, though relatively few have been adequately surveyed to assess their efficacy (Mata et. al.. 2008). The largest and most expensive of all wildlife crossing structures are fauna overpasses or land-bridges. Although now abundant in Europe (France alone has over 200 (Corlatti et. al.. 2009)), four have now been constructed in Australia, with the two most recent being situated within suburban Brisbane. The Compton Road land-bridge is part of the Compton Road Fauna Structures Array, designed to provide continuity of habitat between major bushland to the north and south of the road, and was completed in 2005 (Fig 1). Monitoring of fauna use of this structure has continued since the end of construction (Veage & Jones 2008). As with overpasses worldwide, most attention has been on the use of the structure by mammal species, although some studies have included mention of other taxa (Bond and Jones 2008). With few exceptions, birds have not been considered in such studies, presumably because of the assumption that flight enables safe passage over roads, regardless of width and traffic volume (Jacobson 2005). In a small study of two land-bridges in Germany, however, Keller et. al.. (1996) found that while a number of open country bird species did fly over the road freely, many forest species avoided the road edge. Nonetheless, some of these species were found to cross the road by moving within the vegetation. Monitoring of the Compton Road land-bridge has demonstrated that the structure is used regularly by three species of macropod and European Brown Hare (Lepus europaeus). The vegetation on the structure, having been planted in 2005 mainly as tube-stock of local provenance, is now a dense, multi-layered habitat with the tallest strata of young trees 2 reaching 3.4-4.0 m in height. The species richness closely resembles that of the surrounding forest, with the addition of about 6 species apparently through natural regeneration. Although species such as Australian Magpie (Cracticus tibicen), Pied Butcherbird (Cracticus nigrogularis) and Torresian Crow (Corvus orru) were noted using the structure soon after construction, it was the unexpected sightings of several small forest bird species within the rapidly growing vegetation which prompted the first systematic surveys of bird presence on the land-bridge. In 2008 we undertook observations on parts of the road with and without a land bridge to identify whether there is a road barrier effect and whether this is ameliorated by the land-bridge. | View Paper |
| Species Richness | Jones, Darryl & Pickvance, Jonathon. (2013). Forest birds use vegetated fauna overpass to cross multi-lane road. Oecologia Australis. 17. 147-156. 10.4257/oeco.2013.1701.12. | Although wildlife overpasses have been constructed in many countries to provide safe crossing passages over roads, most have been focused on larger species of mammals. Bird use of these large structures has largely been ignored, although the impact of roads on birds is of increasing concern, especially among smaller, forest-interior species. We studied birds crossing a four-lane road over the road either above the surface or via a vegetated wildlife overpass near Brisbane, Australia, over two years. A total of 14 species were detected crossing the road between the forest edges away from the structure. These were mainly larger species (median weight 110g). In contrast, 25 species of mainly smaller species (median weight 15g) were detected using the wildlife overpass, primarily within the dense planted foliage, with an additional 14 species crossing the road directly above the structure. Although detected only occasionally during the study, the presence of species typically known only from the forest interior in the foliage of the wildlife overpass was especially noteworthy. Moreover, there was strong evidence that the wildlife overpass was being actively used as a corridor. Thus, as many smaller forest-dwelling species appear to be reluctant to cross roads, the construction of this vegetated wildlife overpass appears to have facilitated opportunities for movement that has been exploited by local species. Finally, these results strongly suggest that many of the large number of wildlife overpasses could be converted into safe passages over roads for a much larger proportion of the local biodiversity than has often been previously considered. | View Paper |
| Population Abundance | Jones, Menna E. Road upgrade, road mortality and remedial measures: impacts on a population of eastern quolls and Tasmanian devils | The impact of road mortality on local populations of wildlife has rarely been quantified. In June 1991, the access road into the northern end of the Cradle Mountain Lake St Clair National Park in Tasmania was widened and sealed. This occurred part-way through an ecological study of the dasyurid carnivore guild, during which populations were being monitored. In 17 months, the resident population of 19 eastern quolls became extinct and the devil population, of 39 individuals, halved. Concurrently, there was a dramatic increase in the number of road-kills. The main causal factor was probably an increase in modal speed of about 20 km h1 and a greater increase in maximum speed. Measures were implemented to reduce the incidence of vehicle/wildlife collisions. Measures directed at people included physically slowing traffic speed (using "slow points") and increasing driver awareness (signs and pamphlets). Those directed at wildlife included deterring wildlife from crossing the road in the path of approaching vehicles (wildlife reflectors), and encouraging escape off the road (ramps across gutters and banks, and pipes for shelter). The "slow points" were effective in reducing vehicle speeds by 20 km h1. Wildlife used the ramps and pipes. The eastern quoll population was re-establishing within six months, and after two years, had recovered to 50% of its former level. There was some indication that devil populations were recovering. | View Paper |
| Species Richness | Jung et. al. A comparison of diversity and composition of carabid beetles between overpasses and underpasses in fragmented forest areas | Wildlife crossing structures are important for increasing biodiversity of wildlife and other animals. Thus, the objective of this study was to compare the community structure of carabid beetles along environmental transects of forest-edge-crossing structures in fragmented forest areas. In addition, we also investigated whether there were differences in carabid beetle assemblages due to structural differences in crossing structures, i.e., overpass and underpass. A total of 3,737 carabid beetles belonging to 60 species were collected by pitfall trapping across environmental transects from June 6 to September 3, 2015. In crossing structures, environmental variables, such as soil texture, soil organic matters, and habitat structures were different from those in neighboring habitats. Abundance and species richness of carabid beetles in underpasses were significantly lower than those in neighboring habitats and overpasses. In particular, underpasses, especially those with more artificial structures in terms of soil properties and microhabitat, appeared to be less appropriate structures for movement of carabid beetles. Although less carabid beetle species were caught in crossing structures, species composition of carabid beetles were more similar to forest areas. In conclusion, efforts are needed to improve the connectivity of habitats and consider the needs of invertebrates by providing suitable microhabitats for wildlife crossing structures. | View Paper |
| Species Movement and Dispersal | Kim, Myoung Soo, The Existing Conditions and Problems of Ecological Corridor in Korea - Focusing on Planting Species - | Ecological corridor is the facility to connect two habitats fragmented by roads, dam, housing and industrial area. Critics of faunal corridors have suggested that they are simply an untested application of unproved island biogeography theory. But, everyone agree that ecological corridor is important useful structural components that help animal movement in fragmented landscapes. There are 52 ecological corridors in Korea. We investigated 43 ecological corridors of these and recorded the size of corridor, planting species, management and growth condition. We compared planting species to nearby exiting vegetation species and structure. We found that there are no considerations for many aspects of planting, for example, planting species, structure, animal migration and behavior, surrounding vegetation etc. Expecially, It was ignored management of plants, difference of surrounding vegetation, lacks of diverse planting species and structure. We suggest planting the native species of tall tree, shrub and ground cover, edge planting for transitional space between road and natural habitat, planting for foraging and breeding of target animal, diverse layer vegetation, and open space of center for rapid animal dispersal. | View Paper |
| Plant Dispersal | Kirchner, F., Ferdy, J.-B., Andalo, C., Colas, B., & Moret, J. (2003). Role of Corridors in Plant Dispersal: An Example with the Endangered Ranunculus nodif lorus. Conservation Biology, 17(2), 401-410. | The proposition that the migration of organisms between habitat patches could be enhanced by corridors has been much discussed among conservation biologists. But the few experimental studies supporting the usefulness of corridors have all concerned animal species. We investigated the role of corridors in seed dispersal, studying population genetic and demographic structure in metapopulations of the rare, pond-dwelling, autogamous plant species Ranunculus nodiflorus L. in the Fontainebleau Forest (France). Differentiation on three polymorphic isozyme markers was strong among local populations (ponds) within metapopulations (sites) and moderate among metapopulations. Partial Mantel tests revealed that the connection of ponds through temporarily flooded natural corridors, facilitating seed migration, had a strong negative effect on genetic differentiation between local populations and that a pond was more likely to be colonized when connected by corridors to other occupied ponds. Thus, corridors are probably a key element of landscape structure for metapopulation dynamics in R. nodiflorus. From a conservation perspective, our results suggest that corridors could increase the chance of persistence of plant species living in fragmented habitats by promoting seed dispersal between habitat patches. | View Paper |
| Plant Dispersal | Kormann, U., Scherber, C., Tscharntke, T., Klein, N., Larbig, M., Valente, J. J., Betts, M. G. (2016). Corridors restore animal-mediated pollination in fragmented tropical forest landscapes. Proceedings of the Royal Society B: Biological Sciences, 283(1823). | The proposition that the migration of organisms between habitat patches could be enhanced by corridors has been much discussed among conservation biologists. But the few experimental studies supporting the usefulness of corridors have all concerned animal species. We investigated the role of corridors in seed dispersal, studying population genetic and demographic structure in metapopulations of the rare, pond-dwelling, autogamous plant species Ranunculus nodiflorus L. in the Fontainebleau Forest (France). Differentiation on three polymorphic isozyme markers was strong among local populations (ponds) within meta-populations (sites) and moderate among metapopulations. Partial Mantel tests revealed that the connection of ponds through temporarily flooded natural corridors, facilitating seed migration, had a strong negative effect on genetic differentiation between local populations and that a pond was more likely to be colonized when connected by corridors to other occupied ponds. Thus, corridors are probably a key element of landscape structure for metapopulation dynamics in R. nodiflorus. From a conservation perspective, our results suggest that corridors could increase the chance of persistence of plant species living in fragmented habitats by promoting seed dispersal between habitat patches. | View Paper |
| Species Movement and Dispersal | Kowalski, G. J., Grimm, V., Herde, A., Guenther, A., & Eccard, J. A. (2019). Does Animal Personality Affect Movement in Habitat Corridors? Experiments with Common Voles (Microtus arvalis) using Different Corridor Widths. Animals, 9(6), 291 | Animal personality may affect an animal's mobility in a given landscape, influencing its propensity to take risks in an unknown environment. We investigated the mobility of translocated common voles in two corridor systems 60 m in length and differing in width (1 m and 3 m). Voles were behaviorally phenotyped in repeated open field and barrier tests. Observed behavioral traits were highly repeatable and described by a continuous personality score. Subsequently, animals were tracked via an automated very high frequency (VHF) telemetry radio tracking system to monitor their movement patterns in the corridor system. Although personality did not explain movement patterns, corridor width determined the amount of time spent in the habitat corridor. Voles in the narrow corridor system entered the corridor faster and spent less time in the corridor than animals in the wide corridor. Thus, landscape features seem to affect movement patterns more strongly than personality. Meanwhile, site characteristics, such as corridor width, could prove to be highly important when designing corridors for conservation, with narrow corridors facilitating faster movement through landscapes than wider corridors | View Paper |
| Invasive Species | Kowarik, I., & Moritz von, d. L. (2011). Secondary wind dispersal enhances long-distance dispersal of an invasive species in urban road corridors. NeoBiota, 9, 49-70. | View Paper | |
| Species Movement and Dispersal, Species Richness | Krauze-Gryz, D. & Gryz, J.. (2016). Evaluation of a new wildlife overpass on S7 expressway (central Poland). Annals of Warsaw University of Life Sciences-SGGW, Forestry and Wood Technology. 94. 224-230. | Evaluation of a new wildlife overpass on S7 expressway (central Pol and). The aim of the study was to monitor a new opened overpass (50 m wide) in order to evaluate how fast after the opening and which species of medium and large mammals use the linkage. The overpass is the biggest wildlife passage located on S7 expressway (Bialobrzegi-Jedlinsk sector), crossing one of the main ecological corridors in Poland (the Pilica river valley). Over six months period ( 11 controls) tracks were recorded either in the mud or snow. Altogether 11 species were detected (ungulates, lagomorphs and carnivores) . The most often records were: red fox Vulpes vulpes (Linnaeus, 1758), European hare Lepus europaeus Pallas, 1778 and domestic dog Canis lupus f. familiaris. The species that was recorded only once was red deer Cervus elaphus Lin naeus , 1 758. Nine controls were necess ary to record all the species. The biggest share of all the recorded tracks were le ft by Europea n hare. The biggest number of crossings per control was recorded for European hare and roe deer roe deer Capreolus capreolus (Linnaeus, 1758). AU the ungulates (roe deer, red deer, fallow deer Dama dama (Li nnaeus , 1758), moose AIc es alces (Linnaeus , 1758) and lagomorphs present in the area used the overpass. As the road crosses an ecological corridor of national importance it is advisable that a systematic monitoring of all the possible linkages is promptl y undertak en in order to assess road permeability. | View Paper |
| Benefits and Consequences For Local Communities | Kretzmann, John, and John P. McKnight. "Assets-Based Community Development." National Civic Review 85, no. 4 (1996): 23-29. | View Paper | |
| Ecosystem Services, Species Movement and Dispersal, Population Abundance, Benefits and Consequences For Local Communities | Krost, Peter & Goerres, Matthias & Verena, Sandow. (2018). Wildlife corridors under water: an approach to preserve marine biodiversity in heavily modified water bodies. Journal of Coastal Conservation. 22. 10.1007/s11852-017-0554-0. | Coastal areas commonly consist of an environment of intense economic uses and are thus exposed to conflicts between anthropogenic activities and biodiversity. While several approaches of nature protection have been applied to the terrestrial domain, aquatic biotopes frequently still lack a good ecological state as required by EU policies (WFD and MSFD). For numerous years, the underwater world has been considered as one sphere and was neglected in the development of distinctive concepts of conservation for its variety of biotopes. This paper's objective is the enhancement of ecological connectivity within the study area through the design of benthic wildlife corridors and a consequent sublittoral biotope network. A step-by-step approach is presented for the optimization of ecological potential in heavily modified coastal water bodies, using Kiel Fjord (Western Baltic Sea) as a case study. The procedure for the development of wildlife corridors includes defining and mapping of existing biotope types, the identification of key species for each biotope type and delineating their mobility range, the reconstruction of near-natural / pre-industrial conditions and deriving the protection priorities by comparing past with current / modified conditions. By harmonizing these scientific insights with the local land use of human society, proposals for biotope restoration and improvements can be made. In Kiel Fjord, compensation measures, obligatory for human interventions, such as construction work in the marine environment in this case, have been implemented and present an opportunity to enhance the connectivity of biotopes, thus creating wildlife corridors for their inhabitants. The composition of benthic wildlife corridors, forming a sublittoral biotope network in accordance with the present anthropogenic uses, holds potential for implementation in comparably altered coastal water bodies and integration into national and international frameworks, in anticipation of its functionality. | View Paper |
| Species Movement and Dispersal | Kusak, J., Huber, D., Gomerčić, T. et al. The permeability of highway in Gorski kotar (Croatia) for large mammals. Eur J Wildl Res 55, 7–21 (2009). https://doi.org/10.1007/s10344-008-0208-5 | The highway from Zagreb to Rijeka stretches 68.5 km through a wildlife core area in Gorski kotar (Croatia). It has 43 viaducts and tunnels, and one specifically constructed (100 m wide) green bridge (Dedin). One quarter of the total highway length consists of possible crossing structures. At Dedin green bridge, a total of 12,519 crossings have been recorded during 793 different days of active infrared monitors being in operation, or 15.8 crossings per day. Two monitored tunnel overpasses had 11.2 and 37.0 crossings per day, respectively, whilst 4.3 crossings occurred per day under one monitored viaduct. Of those crossings, 83.2% were by ungulates and 14.6% by large carnivores. Radio-tracked large carnivores, brown bear (Ursus arctos), grey wolf (Canis lupus) and Eurasian lynx (Lynx lynx), expressed strong positive selection for tunnels and viaducts, whilst avoiding small underpasses or bridges. Selection for the use of Dedin green bridge was equal to its availability. We conclude that this green bridge, constructed as a measure to mitigate the negative effects of the studied highway, served its purpose acceptably. Territorial and dispersing radio-tracked large carnivores crossed the highway 41 times, using both sides of the highway as parts of their home ranges. Overall, the highway in Gorski kotar does not seem to be a barrier. This demonstrates that it is possible to maintain habitat connectivity during the process of planning the highway route. | View Paper |
| Population Abundance | La Polla, V. N., & Barrett, G. W. (1993). Effects of corridor width and presence on the population dynamics of the meadow vole (Microtus pennsylvanicus). Landscape Ecology, 8(1), 25-37. | We tested the effects of increased landscape corridor width and corridor presence on the population dynamics and home range use of the meadow vole (Microtus pennsylvanicus) within a small-scale fragmented landscape. Our objective was to observe how populations behaved in patchy landscapes where the animals home range exceeded or equaled patch size. We used a small-scale replicated experiment consisting of three sets of two patches each, unconnected or interconnected by 1-m or 5-m wide-corridors, established in an old-field community (S.W. Ohio). Control (0-m) treatments supported significantly lower vole densities than either corridor treatment. Females were the dominant resident sex establishing smaller home ranges (<150m2) than males (>450m2). Significantly more male voles dispersed between patches with corridors than between patches without corridors. However, no difference was observed regarding the number of male voles dispersing between patches connected by corridors when compared to the number dispersing across treatments. Dispersal between connected patches was restricted to corridors based on tracking tube data. Corridor presence was more important than corridor width regarding the movement of male voles within their home range. | View Paper |
| Species Movement and Dispersal | Laurance, S. G., & Laurance, W. F. (1999). Tropical wildlife corridors: use of linear rainforest remnants by arboreal mammals. Biological Conservation, 91(2-3), 231-239 | In fragmented landscapes, linear forest remnants have the potential to provide habitat and movement corridors for wildlife. We used systematic spotlighting surveys to sample arboreal mammals in 36 linear rainforest remnants in tropical Queensland, Australia. The effects of corridor width, height, isolation, elevation, and floristic composition on mammals were assessed with multiple regression models. Six species were recorded during 108 surveys. The most vulnerable species, the lemuroid ringtail possum (Hemibelideus lemuroides), was found only in remnants comprised of primary rainforest that were linked to large tracts of continuous forest. Two other species, the Herbert River ringtail possum (Pseudochirulus herbertensis) and striped possum (Dactylopsila trivirgata), also favored corridors that were linked to forest tracts or fragments, with the former favoring high-diversity forest (primary forest or mixed regrowth) over low-diversity (Acacia) regrowth. Three other species, the coppery brushtail possum (Trichosurus vulpecula), green ringtail possum (Pseudochirops archeri), and Lumholtz's tree-kangaroo (Dendrolagus lumholtzi), occurred in both isolated and non-isolated remnants and both primary forest and regrowth. Our findings suggest that linear forest remnants that are floristically diverse (not Acacia-dominated regrowth) and at least 30-40 m width can function as habitat and probably movement corridors for most arboreal mammals in this region. The lemuroid ringtail, however, apparently requires corridors of primary rainforest of at least 200 m in width. Because the lemuroid ringtail is highly vulnerable to forest fragmentation, faunal corridors in this region should be designed wherever possible to meet its ecological requirements. | View Paper |
| Species Movement and Dispersal | Lechner, A.M., Sprod, D., Carter, O. et. al.. Characterising landscape connectivity for conservation planning using a dispersal guild approach. Landscape Ecol 32, 99–113 (2017). | ContextLand use changes have modified the extent and structure of native vegetation, resulting in fragmentation of native species habitat. Connectivity is increasingly seen as a requirement for effective conservation in these landscapes, but the question remains: ‘connectivity for which species?’. Objective The aim of this study was to develop and then apply a rapid, expert-based, dispersal guild approach where species are grouped on similar fine-scale dispersal behaviour (such as between scattered trees) and habitat characteristics. Methods Dispersal guilds were identified using clustering techniques to compare dispersal and habitat parameters elicited from experts. We modelled least-cost paths and corridors between patches and individual movement probabilities within these corridors for each of the dispersal guilds using Circuitscape. We demonstrate our approach with a case study in the Tasmanian Northern Midlands, Australia. ResultsThe dispersal guild approach grouped the 12 species into five dispersal guilds. The connectivity modelling of those five guilds found that broadly dispersing species in this landscape, such as medium-sized carnivorous mammals, were unaffected by fragmentation while from the perspective of the three dispersal guilds made up of smaller mammals, the landscape appeared highly fragmented. Conclusions Our approach yields biologically defensible outputs that are broadly applicable, particularly for conservation planning where data and resources are limited. It is a useful first step in multi-species conservation planning which aims to identify those species most in need of conservation efforts. | View Paper |
| Ecosystem Services | Lee, J. A., Chon, J., & Ahn, C. (2014). Planning Landscape Corridors in Ecological Infrastructure Using Least-Cost Path Methods Based on the Value of Ecosystem Services. Sustainability, 6(11), 7564-7585. doi: 10.3390/su6117564 | Ecosystem service values have rarely been incorporated in the process of planning ecological infrastructure for urban areas. Urban ecological infrastructure is a network system of natural lands and waters that provides ecosystem services. The purpose of this study was to design landscape corridors that maximize the value of ecosystem services in ecological infrastructure planning. We explored the optimal corridors to enhance the connectivity among landscape elements to design an ecological infrastructure for the city of Gwacheon, South Korea, as an example of a small urban area. We calculated the value of ecosystem services using standardized estimation indices based on an intensive review of the relevant literature and employed the least-cost path method to optimize the connectivity of landscape structural elements. The land use type in the city with the highest estimated value of ecosystem services was the riparian zone‚ (i.e., 2011 US$7,312.16/ha). Given areal coverage of all land use types, the estimated value of developed area open spaces was 2011 US$899,803.25, corresponding to the highest contribution to the total value of ecosystem services. Therefore, the optimal configured dispersal corridors for wildlife were found from the riparian zones (source area) to the developed area open spaces (destination area) in the city. Several challenges remain for improving the estimation of the value of ecosystem services and incorporating these ecosystems in ecological infrastructure planning. Nonetheless, the approaches taken to estimate the value of ecosystem services and design landscape corridors in this study may be of value to future efforts in urban ecological infrastructure planning. | View Paper |
| Species Richness | Lees, A.C. and C. Peres, Conservation value of remnant riparian forest corridors of varying quality for Amazonian birds and mammals. Conservation biology, 2008. 22(2): p. 439-449. | Forest corridors are often considered the main instrument with which to offset the effects of habitat loss and fragmentation. Brazilian forestry legislation requires that all riparian zones on private landholdings be maintained as permanent reserves and sets fixed minimum widths of riparian forest buffers to be retained alongside rivers and perennial streams. We investigated the effects of corridor width and degradation status of 37 riparian forest sites (including 24 corridors connected to large source-forest patches, 8 unconnected forest corridors, and 5 control riparian zones embedded within continuous forest patches) on bird and mammal species richness in a hyper-fragmented forest landscape surrounding Alta Floresta, Mato Grosso, Brazil. We used point-count and track-sampling methodology, coupled with an intensive forest-quality assessment that combined satellite imagery and ground truthed data. Vertebrate use of corridors was highly species-specific, but broad trends emerged depending on species life histories and their sensitivity to disturbance. Narrow and/or highly disturbed riparian corridors retained only a depauperate vertebrate assemblage that was typical of deforested habitats, whereas wide, well-preserved corridors retained a nearly complete species assemblage. Restriction of livestock movement along riparian buffers and their exclusion from key areas alongside deforested streams would permit corridor regeneration and facilitate restoration of connectivity. | View Paper |
| Species Movement and Dispersal | Lindenmayer, D.B. and Nix, H.A. (1993), Ecological Principles for the Design of Wildlife Corridors. Conservation Biology, 7: 627-631. https://doi.org/10.1046/j.1523-1739.1993.07030627.x | The establishment of ecological networks (ENs) has been proposed as an ideal way to counteract the increasing fragmentation of natural ecosystems and as a necessary complement to the establishment of protected areas for biodiversity conservation. This conservation tool, which comprises core areas, corridors, and buffer areas, has attracted the attention of several national and European institutions. It is thought that ENs can connect habitat patches and thus enable species to move across unsuitable areas. In Europe, however, ENs are proposed as an oversimplification of complex ecological concepts, and we maintain that they are of limited use for biodiversity conservation for several reasons. The ENs are species specific and operate on species-dependent scales. In addition, the information needed for their implementation is only available for a handful of species. To overcome these limitations, ENs have been proposed on a landscape scale (and for selected "focal" species), but there is no indication that the structural composition of core areas, corridors, and buffer areas could ensure the functional connectivity and improve the viability of more than a few species. The theory behind ENs fails to provide sufficient practical information on how to build them (e.g., width, shape, structure, content). In fact, no EN so far has been validated in practice (ensuring connectivity and increasing overall biodiversity conservation), and there are no signs that validation will be possible in the near future. In view of these limitations, it is difficult to justify spending economic and political resources on building systems that are at best working hypotheses that cannot be evaluated on a practical level. | View Paper |
| Species Richness | Longcore, Travis & Almaleh, Lindsay & Chetty, Brittany & Francis, Kathryn & Freidin, Robert & Huang, Ching-Sheng & Pickett, Brooke & Schreck, Diane & Scruggs, Brooke & Shulman, Elise & Swauger, Alissa & Tashnek, Alison & Wright, Michael & Boydston, Erin. (2018). Wildlife Underpass Use and Environmental Impact Assessment: A Southern California Case Study. 11. art 4. | Environmental planners often rely on transportation structures (i.e., underpasses, bridges) to provide connectivity for animals across developed landscapes. Environmental assessments of predicted environmental impacts from proposed developments often rely on literature reviews or other indirect measures to establish the importance of wildlife crossings. Literature-based evaluations of wildlife crossings may not be accurate, and result in under-estimation of impacts or establishment of inappropriate mitigation measures. To investigate the adequacy of literature-based evaluations, we monitored wildlife use of a freeway underpass that had been identified as critically important to wildlife connectivity, and which was evaluated in an environmental review document. Photographs were obtained from a network of trail cameras over 3 years. Six mid- to large-sized native mammal species used the underpass and two other mammal species were photographed near the underpass but not using it. American badger (Taxidea taxus) was photographed at a higher rate in the underpass than in the surrounding area. Gray fox (Urocyon cinereoargenteus) was rarely detected in the underpass relative to surrounding habitats, whereas the absence of mule deer (Odocoileus hemionus) in the underpass was unexpected, given relatively frequent detection in adjacent habitats. These results differed from the environmental assessment in that American badger was listed as "potentially" present while mule deer were expected to use the underpass. Results underscore importance of gathering data to document wildlife use of corridors, because some species do not or rarely take advantage of apparently suitable corridors, while others may be present when assumed to be absent | View Paper |
| Species Movement and Dispersal | Luckett, J., Danforth, E., Linsenbardt, K., & Pruetz, J. (2004). Planted trees as corridorsfor primates at El Zota Biological Field Station, Costa Rica. Neotropical Primates , 12 (3),143–146. | We conducted a study at the privately owned El Zota Biological Field Station in Costa Rica to assess the effects of forest management techniques on primate ecology and behavior. While many conservation-oriented studies note the need for corridors to promote dispersal between isolated habitat fragments, few studies provide quantitative information on their use by primates. From July to August 2002, we studied the three primate species that occur at the El Zota Biological Field Station in Costa Rica Cebus capucinus, Ateles geoffroyi, Alouatta palliata to compare their use of planted versus naturally forested areas. We collected ap- proximately 25 hours of data to quantify the general activities exhibited by primates in these types of habitat. | View Paper |
| Species Movement and Dispersal, Species Richness | Lyren, L. M, & Crooks, D. R. (2001). Factors influencing the movement, spatial patterns, and wildlife underpass use of coyotes and bobcats along State Route 71 in Southern California. UC Davis: Road Ecology Center. | Mammalian carnivores may be sensitive to habitat fragmentation due to roadway construction. As a solution, roadway underpasses have received increasing attention; however, relatively little data exist on how carnivores respond to roadways or use the underpasses. We present results from a study of movement patterns and underpass use of coyotes and bobcats along CA 71, a freeway bisecting the eastern end of the Puente-Chino Hills wildlife corridor in urban Los Angeles. Recent reconstruction of a 5-km segment included installation of wildlife fencing, three large wildlife culverts, and 20 smaller water culverts. From February 1998 to February 2000, we captured and radio-tracked 29 coyotes and 4 bobcats and fitted an additional 24 coyotes with dog collars. Telemetry data were augmented by remotely triggered camera surveys at the culverts. Mean home range sizes for 15 coyotes and 3 bobcats were 13.72±3.92 and 8.89±3.45 km2 while core-use area sizes were 1.71±0.48 and 1.31±0.40 km2, respectively; both area sizes differed between age and social classes. Nine individuals maintained core-use areas that overlapped roadways and several had linear home ranges paralleling the roadways. Buffer zones established alongside roadways were not used proportional to their availability by 10 individuals. Telemetry and remotely triggered cameras documented 320 roadway crossings, which included 150 confirmed uses of underpasses by 16 collared individuals. However, hourly traffic volume influenced frequency of culvert use. In addition, surface crossings, particularly in areas where wildlife fencing was absent, accounted for 67 percent of study animal mortality. Mortality patterns for age classes and traffic direction differed. Overall, our study has provided valuable information for the California Department of Transportation on factors influencing underpass use and the effectiveness of roadway design for target species in fragmented landscapes. | View Paper |
| Benefits and Consequences For Local Communities | MacDonald, J. 2016, December 12). Do Wildlife Corridors Work? | The world is running out of space for wildlife. National parks and other protected areas can have great benefits, but can end up functioning as islands where populations of a species are geographically and genetically isolated from other populations. Fragmentation of unprotected habitat can result in areas too small to support some species. One longstanding idea is to create narrow “corridors” of protected habitat linking larger protected areas where species in theory can move easily between larger protected areas. This idea is about to be tested on a large scale in Sumatra, where a network of corridors linking endangered populations of orangutans, tigers, and other wildlife is under development. The biggest question regarding habitat corridors is “Do they work?” According to a 1998 study, it can be hard to tell. It’s difficult to isolate a corridor’s performance from other factors. Just because wildlife doesn’t use a corridor does not automatically mean it’s the fault of the corridor. For example, the patches being connected might not hold much wildlife to begin with. That 1998 study concluded that it’s a difficult topic to study, but that on balance corridors tend to be beneficial for wildlife. | View Paper |
| Species Movement and Dispersal | Machtans, C.S., Villard, M.‐A. and Hannon, S.J. (1996), Use of Riparian Buffer Strips as Movement Corridors by Forest Birds. Conservation Biology, 10: 1366-1379. | We conducted a 3-year field experiment to measure the frequency of bird movements through riparian buffer strips before and after harvesting of adjacent forest. Our study was conducted in the boreal mixed wood forest of Alberta and was designed to determine empirically whether songbirds use riparian buffer strips of forest connecting forest reserves as corridors and if they move along these buffer strips more frequently than they cross adjacent clearcuts. We use mist nets to obtain an index of the frequency of bird movement in the forest, and we observed bird movements across adjacent clearcuts for comparison. We predicted that the frequency of movement would be greater (1) in buffer strips after harvesting of adjacent forest than before harvesting, (2) in buffer strips than across clearcuts and, (3) in buffer strips than at control sites (lakeshore forest with no adjacent clearcuts). After adjusting for year-to-year variation in abundance, we found that capture rates increased significantly from pre- to post-harvest, but only for juveniles. Capture rates of adults decreased immediately after harvesting, probably because of the removal of an adjacent source of birds that previously moved through the lakeside forest. Movement rates of forest species in clearcuts were significantly lower than capture rates in the forest. The number of adults captured was positively correlated with the number of territories in the buffer strips, indicating that most birds captured were probably residents. The number of local territories was a poor predictor of juvenile captures, supporting the notion that juveniles were likely dispersing individuals. Our results indicate that buffer strips enhanced movements of juveniles (i.e. acted as corridors) and maintained movement rates of adults. Furthermore, there appeared to be a threshold distance between reserves below which birds may be less reluctant to fly across openings making corridor use less important. | View Paper |
| Invasive Species | Mack, R. N., Simberloff, D., Lonsdale, W. M., Evans, H., Clout, M., & Bazzaz, F. A. (2000). Biotic Invasions: Causes, Epidemiology, Global Consequences, and Control. Ecological Applications, 10(3), 689-710. | Humans have surpassed natural forces as the‚ principal global disperser of vascular plants. Some of the means of dispersal are accidental: Seeds and other plant disseminules and vegetative propagules are transported inadvertently in clothing; cling to or are ingested by our domesticated animals; and are found within and attached to all manner of commerce, particularly as contaminants in seed lots (Muenscher 1955). Plants are also deliberately transported. Almost all human societies have long been dependent on the deliberate transport of plants as a means to satisfy basic human needs (Mack 1999). Many ancient accounts of plant transport are probably apocryphal, such as the importation of incense trees by Queen Hatshepsut to Egypt in 1500 BC from the Land of Punt (Hodge and Erlanson 1956), but there is nevertheless a verifiable fossil record documenting the cultivation of plants far from their native ranges for thousands of years (Godwin 1975). | View Paper |
| Species Richness | Malkoc, G. (2015). Road Maintenance: A Priority. World Highways, June 2015. | Roads make a crucial contribution to economic development and growth and bring important social benefits. They are of vital importance in order to make a nation grow and develop. In addition, providing access to employment, social, health and education services makes a road network crucial in fighting against poverty. Roads open up more areas and stimulate economic and social development. For those reasons, road infrastructure is the most important of all public assets. | View Paper |
| Benefits and Consequences For Local Communities | Manjaribe, Christophe, Cynthia L. Frasier, Bakolimalala Rakouth, and Edward E. Louis. "Ecological Restoration and Reforestation of Fragmented Forests in Kianjavato, Madagascar." International Journal of Ecology 2013 (2013): 1-12 | A reforestation effort in Kianjavato Commune in southeast Madagascar is presented that combines native diversity with rapidly growing introduced and native pioneer trees. This work utilizes a three-tiered corridor design that capitalizes on the region's mountainous terrain. The process of seed selection, transplantation, and survival rate of seedlings over a 16 month period is reported. The uppermost 50% of each mountain is planted with 38 woody species and most closely approximates native forest. This tier was divided into two categories, pioneer and secondary species. Most of the pioneer species were not native; however, results showed that four fast-growing, environmentally-tolerant native species could be suitable alternatives: Streblus mauritianus, Syzygium bernieri, Treculia madagascariensis and Uapaca thouarsii. More than 70,000 seeds of secondary species were extracted from fecal samples from wild, free-ranging black and white ruffed lemurs; the majority of which germinated significantly better after gut passage. The most effective pretreatment that enhanced germination was to scarify unwashed seeds. Commercially valuable trees, belonging to the community members, were grown on the lower half of each mountain. Lastly, the various contributions of the community are described along with agroforestry development plans designed to reduce pressure on forest resources and generate supplemental income. | View Paper |
| Population Abundance | Mansergh, Ian & Scotts, David. (1989). Habitat Continuity and Social Organization of the Mountain Pygmy-Possum Restored by Tunnel. The Journal of Wildlife Management. 53. 701. 10.2307/3809200. | We demonstrate that the social organization and survival rates of the mountain pygmy-possum (Burramys parvus), a rare Australian marsupial, had been disrupted because its habitat had been fragmented by roads and other developments within a ski resort. We restored habitat continuity by constructing a corridor leading to 2 tunnels beneath a road that bisected the breeding area. The corridor and tunnels were filled with rocks that imitated the natural habitat of scree. These constructions allowed males to disperse from the female breeding areas; such dispersal is an essential element in the species social organization. After construction the population structure and survival rates in the disturbed area changed to those observed in the undisturbed area. Our results indicate that wildlife managers should consider that dispersal of individuals plays an important role in the social structure of wildlife populations and corridors and tunnels are strategies available for management of wildlife populations in habitats fragmented by roads and other man-made stuctures. | View Paper |
| Genetic Variation | Marquardt and Marcus Molecular Tools for Understanding Landscape Genetics and the Population Genetic Effects of Habitat Restoration on Butterflies | Habitat corridor construction is an important technique for re-establishing connections between fragmented habitats. Yet, the effectiveness of habitat corridors to increase gene flow among fragmented populations is not well studied. In 2008 and 2009, a prairie habitat corridor was created in the Green River watershed of south central Kentucky, USA to protect water quality and encourage movement of native wildlife as part of the US Environmental Protection Agency Conservation Reserve Enhancement Program (CREP). In 2008, prior to the establishment of the habitat corridor, we documented the population genetic structure of 6 butterfly species (Chlosyne nycteis, Cupido comyntas, Phoebis sennae, Phyciodes tharos, Pterourus glaucus, and Pterourus troilus) with different habitat requirements and different expected responses to corridor construction using Randomly Amplified DNA Fingerprint (RAF) markers. STRUCTURE analysis of these markers subdivided each butterfly species into 2 to 8 subpopulations in the Green River watershed. By collecting data in the early stages of habitat restoration, we have established a baseline to compare with data obtained after the corridor has matured to determine the population genetic effects on previously isolated butterfly populations and to provide information about the conservation value of habitat corridors in general. | View Paper |
| Species Movement and Dispersal | Mass V., Rakotomanga B., Rakotondratsimba G., Razafindramisa S., Andrianaivomahefa P., Dickinson S., Berner P.O. & Cooke A. (2011) Lemur bridges provide crossing structures over roads within a forested mining concession near Moramanga, Toamasina Province, Madagascar. Conservation Evidence, 8, 11-18 | The Ambatovy Project includes a large, open-pit nickel mine located in Madagascar's eastern humid forest, and an associated pipeline to remove laterite slurry off site. The area is recognized for its high biodiversity exemplified by the presence of at least 13 lemur species in forests surrounding the mine site. In order to reduce potential habitat fragmentation impacts on the lemur populations as a consequence of recent access road construction, seven crossing structures (referred to as lemur bridges) were erected within the mine footprint area and along the slurry pipeline that will remain in place until rehabilitated forest allows for movement over roads via the forest canopy. Two bridge designs were used due to differences in road width and vehicle traffic type. Lemur bridges have been monitored since their construction in January-February 2009. To date (10 August 2010), bridges have been used by six lemur species. Mine footprint type bridges (suspension bridge design) have been used more frequently than slurry pipeline bridges (plank bridge design) and, overall, there has been an increase in bridge use in 2010 when compared to 2009 (from 8 % to 24 % of total observations where lemurs are present in proximity to bridges). These results suggest that although a certain time period may be required for lemurs to locate and habituate to bridges, these crossing structures offer an effective mitigation measure to assist in reducing the impacts of habitat fragmentation. | View Paper |
| Species Richness | Mata Estacio, Cristina & Hervás, Israel & Herranz, Jesús & Suárez, F & Malo, Juan. (2008). Are motorway wildlife passages worth building? Vertebrate use of road-crossing structures on a Spanish motorway. Journal of environmental management. 88. 407-15. 10.1016/j.jenvman.2007.03.014. | Numerous road and railway construction projects include costly mitigation measures to offset the barrier effect produced on local fauna, despite the scarcity of data on the effectiveness of such mitigation measures. In this study, we evaluate the utility of different types of crossing structures. Vertebrate use of 43 transverse crossing structures along the A-52 motorway (north-western Spain) was studied during spring 2001. Research centered on wildlife passages (9), wildlife-adapted box culverts (7), functional passages (6 overpasses, 7 underpasses) and culverts (14), with marble dust being used to record animal tracks. A total of 424 track-days were recorded, with most of the larger vertebrate groups present in the area being detected. All crossing structure types were used by animals, although the intensity of use varied significantly among them (Kruskal-Wallis test, p <0.05); culverts were used less frequently than other structures. Crossing structure type and width were identified as the most important factors in their selection for use. Wildlife passages and adapted culverts allowed crossing by certain species (wild boar, roe deer, Eurasian badger), which do not tend to cross elsewhere. These results highlight the importance of using both mixed-type structures and wildlife passages in reducing the barrier effect of roads. Eurasian badger), which do not tend to cross elsewhere. These results highlight the importance of using both mixed-type structures and wildlife passages in reducing the barrier effect of roads. Eurasian badger), which do not tend to cross elsewhere. These results highlight the importance of using both mixed-type structures and wildlife passages in reducing the barrier effect of roads. | View Paper |
| Species Richness | MCCOLLISTER, MATTHEW & Manen, Frank. (2010). Effectiveness of Wildlife Underpasses and Fencing to Reduce Wildlife–Vehicle Collisions. The Journal of Wildlife Management. 74. 1722-1731. 10.2307/40925759. | Transportation planners are increasingly incorporating roadway design features to mitigate impacts of highways on wildlife and to increase driver safety. We used camera and track surveys to evaluate wildlife use before and after construction of 3 wildlife underpasses and associated fencing on a new section of United States Highway 64 in Washington County, North Carolina, USA. We recorded 242 occasions of white-tailed deer (Odocoileus virginianus) use of underpass areas before highway construction began. Following completion of the highway, we collected 2,433 photographs of 9 species with deer representing 93% of all crossings. Adjusting for differences in number of monitoring days, white-tailed deer use of underpass areas averaged 6.7 times greater after the new highway and underpasses were completed. We recorded 3,614 wildlife crossings of ≥20 species based on track counts, representing most medium and large mammals known to occur in the area and several reptiles and birds. After completion of the highway, we documented wildlife mortality due to vehicle collisions during a 13-month period and recorded 128 incidences representing ≥24 species. Within fenced highway segments, mortalities were lowest near underpasses and increased with distance from the underpasses. However, we also documented more mortalities in fenced areas compared with unfenced areas. With greater distance from an underpass, animals with smaller home ranges seemed less likely to reach the underpass and instead attempted to climb over or crawl under fencing. Based on collision reports from adjacent highway sections, the new section of United States Highway 64 experienced approximately 58% fewer wildlife mortalities (primarily white-tailed deer), suggesting underpasses and fencing reduced the number of deer—vehicle collisions. Continuous fencing between underpasses may further reduce the number of vehicle collisions for deer but additional design features (e.g., buried fencing) should be considered for other wildlife species. | View Paper |
| Species Movement and Dispersal | McDonald, Wayne & St. Clair, Colleen. (2004). Elements that promote highway crossing structure use by small mammals in Banff National Park. Journal of Applied Ecology. 41. 82 - 93. 10.1111/j.1365-2664.2004.00877.x. | Corridors provide important structural connectivity in habitats that have been fragmented by human activities, but more empirical work is needed to identify the attributes of effective corridor design under a broad range of ecological conditions. • We tested the efficacy with which murid rodents in Banff National Park, Alberta, Canada, used crossing structures constructed across the Trans-Canada Highway. We studied the effects of size, vegetative cover at entrances, and distance from home ranges as determinants of crossing structure use with potential relevance to other corridor types. • We translocated animals across underpasses and overpasses, coated them with fluorescent dye, released them at standardized distances, and followed them to obtain detailed information on two scale-dependent movement parameters, return success and tortuosity (or complexity) of movement paths, as well as a scale-independent metric of movement, the fractal dimension. • Translocated animals returned with higher success across smaller crossing structures than across larger ones, perhaps because these structures afforded more overhead cover from predators. • Adding overhead cover to crossing structure entrances further improved return success and correlated with more tortuous movement of translocated animals. • Animals translocated further (60 m) from crossing structures returned with lower success than those translocated closer to them (20 and 40 m). Among the three species studied (deer mice Peromyscus maniculatus, meadow voles Microtus pennsylvanicus and red-backed voles Clethrionomys gapperi), deer mice had significantly higher return success at 60 m, perhaps owing to their larger home range sizes and willingness to cross the road directly. • Synthesis and applications. Ideal crossing structure characteristics will often be species-specific, even within guilds of animals. Our results imply that wildlife corridors, more generally, need to offer sufficient cover and be placed with a frequency that corresponds to the spatial scale over which targeted species move. Journal of Applied Ecology (2004) 41, 82–93 | View Paper |
| Species Richness | McGregor, M. (2016). Fauna passages as an effective way to increase habitat connectivity for diverse non-target species. Griffith University. Queensland, Australia. | Urbanisation has become the most significant cause of habitat loss and fragmentation globally, facilitating the rapid expansion of road infrastructure networks which have led to environmental degradation at a scale disproportionate to the land they occupy. More than 20 individual ecological effects are directly attributed to road presence, with road effect zones shown to extend up to thousands of meters beyond the road itself. The effects of roads are generally recognised as being detrimental to most wildlife, occurring at localised patch levels, endangering local wildlife and reducing local habitat, as well as at the landscape scale, where they increase habitat fragmentation and facilitate widespread ecological degradation. | View Paper |
| Species Richness | McGregor, Mel & Wilson, Steve & Jones, Darryl. (2015). Vegetated fauna overpass enhances habitat connectivity for forest dwelling herpetofauna. Global Ecology and Conservation. 4. 221-231. 10.1016/j.gecco.2015.07.002. | The ecological impact of roads and traffic is now widely acknowledged, with a variety of mitigation strategies such as purpose designed fauna underpasses and overpasses commonly installed to facilitate animal movement. Despite often being designed for larger mammals, crossing structures appear to enable safe crossings for a range of smaller, ground dwelling species that exhibit high vulnerability to roads. Less attention has been paid to the extent to which fauna overpasses function as habitat in their own right, an issue particularly relevant to reptiles and amphibians. The Compton Road fauna array (Brisbane, Australia) includes a vegetated fauna overpass which connects two urban forest reserves and traverses a major four lane arterial road. The aim of this study was to quantify the extent to which colonisation of the Compton Road fauna overpass by reptile and amphibian species living in adjacent forests occurred. Pitfall sampling at seven sampling sites occurred between June 2005 and February 2010, starting approximately six months after overpass construction, with additional observational detections throughout this period. The overpass yielded higher species diversity and capture rates compared with the forest areas. Species accumulation curves demonstrated a strong and consistent colonisation rate of the overpass throughout the six year monitoring period, while persistent occupation by species on the overpass throughout the six years suggests permanent colonisation of the vegetated structure as an extension of the natural forest habitat. These outcomes demonstrate that the fauna overpass at Compton Road provides suitable habitat for diverse local herpetofauna communities and suggest enhanced habitat connectivity across the road. | View Paper |
| Genetic Variation | Mech, Stephen G., and James G. Hallett. "Evaluating the effectiveness of corridors: a genetic approach." Conservation Biology 15.2 (2001): 467-474. | The effectiveness of corridors in maintaining dispersal in fragmented landscapes is a question of considerable conservation and ecological importance. We tested the efficacy of corridors as residual landscape structures in maintaining population structure in the red-backed vole (Clethrionomys gapperi), a closedcanopy specialist, and the deer mouse (Peromyscus maniculatus), a habitat generalist. In coniferous forests managed for timber production in northeastern Washington, we sampled pairs of populations in three landscape classes: (1) contiguous landscapes, in which sites were located completely within a matrix of closed-canopy forest; (2) corridor landscapes, in which sites were connected by a corridor of closed-canopy forest; and (3) isolated landscapes, in which sites were separated from one another by clearcut or young regeneration stands. For each species, we used four microsatellite loci to quantify genetic distance between population pairs. Nei's genetic distance (Ds) increased from smallest to largest in the order of contiguous, corridor, and isolated landscapes for C. gapperi. For P. maniculatus, genetic distances across landscape configurations were not significantly different. The differences between the two species indicate that they respond differently to the presence of forest corridors. In managed forests, corridors between unlogged habitats appear to maintain higher population connectivity for C. gapperi than landscapes without corridors. | View Paper |
| Invasive Species | Meek, Paul & Saunders, Glen. (2000). Home range and movement of Foxes (Vulpes vulpes) in coastal New South Wales, Australia. Wildlife Research. 27. 663-668. 10.1071/WR98030. | Data on the home range and activity of 14 foxes was collected from coastal habitat in Jervis Bay, New South Wales during 1993–95. Radio-collared foxes had a mean home range of 135 ha and core activity areas of 23 ha (determined by the Minimum Convex Polygon method). There were no significant differences in the home ranges of male and female foxes. The home ranges of some foxes shifted throughout the study. Some animals went on long forays beyond their normal range. All animals displayed nocturnal activity patterns except during the breeding season or after long spells of wet weather when some foraging occurred during daylight hours. The information collected in this study is discussed in the context of fox control. | View Paper |
| Species Movement and Dispersal | Merriam, G., & Lanoue, A. (1990). Corridor use by small mammals: field measurement for three experimental types of Peromyscus leucopus. Landscape ecology, 4(2-3), 123-131 | Eighteen mice of each of 3 types were radio-tagged and released at 6 standard points in farmland fencerows. Mice were residents (trapped on site) or translocated from distant forest or from distant corn fields. Of total (net) distance moved, most was in fencerows; 77% for residents, 83% for mice translocated from cropland and 92% for mice translocated from forest. Structurally complex fencerows were preferred significantly over intermediate or simple structures by all types of mice. Time spent in movement was not a linear function of distance moved and averaged from 12.5 to 16.5% of total available activity time. Total distance moved in 2 nights averaged 287 to 422 m and area explored averaged 0.67 to 1.15 ha and ranged to 11.0 ha; both exceed literature values for this species in forest. This enlarged scale of landscape use illustrates the potential importance of landscape-specific behaviour. The measurement of rate of corridor use also is discussed. | View Paper |
| Benefits and Consequences For Local Communities, Species Movement and Dispersal | Mesquita, C. A. B., C. G. D. Holvorcem, C. H. Lyrio, P. D. de Menezes, J. D. da Silva Dias, and J. F. Azevedo. COOPLANTAR: A Brazilian Initiative to Integrate Forest Restoration with Job and Income Generation in Rural Areas. Ecological Restoration 28, no. 2 (June 1, 2010): 199-207 | We describe the process leading to the creation of the Cooperative of Reforestation Workers of Far Southern Bahia (COOPLANTAR), a cooperative that specializes in restoration of the Atlantic Forest in the Monte Pascoal¢-Pau Brasil Ecological Corridor in southern Bahia, Brazil, and provides job and income for members of local impoverished communities. We discuss the achievements of the cooperative, difficulties it has faced, and its prospects for future sustainability and expansion. | View Paper |
| Genetic Variation | MUNSHI‐SOUTH, J. (2012), Urban landscape genetics: canopy cover predicts gene flow between white‐footed mouse (Peromyscus leucopus) populations in New York City. Molecular Ecology, 21: 1360-1378. | In this study, I examine the influence of urban canopy cover on gene flow between 15 white?footed mouse (Peromyscus leucopus) populations in New York City parklands. Parks in the urban core are often highly fragmented, leading to rapid genetic differentiation of relatively nonvagile species. However, a diverse array of "green" spaces may provide dispersal corridors through "grey" urban infrastructure. I identify urban landscape features that promote genetic connectivity in an urban environment and compare the success of two different landscape connectivity approaches at explaining gene flow. Gene flow was associated with "effective distances" between populations that were calculated based on per cent tree canopy cover using two different approaches: (i) isolation by effective distance (IED) that calculates the single best pathway to minimize passage through high-resistance (i.e. low canopy cover) areas, and (ii) isolation by resistance (IBR), an implementation of circuit theory that identifies all low-resistance paths through the landscape. IBR, but not IED, models were significantly associated with three measures of gene flow (Nm from FST, BayesAss+ and Migrate-n) after factoring out the influence of isolation by distance using partial Mantel tests. Predicted corridors for gene flow between city parks were largely narrow, linear parklands or vegetated spaces that are not managed for wildlife, such as cemeteries and roadway medians. These results have implications for understanding the impacts of urbanization trends on native wildlife, as well as for urban reforestation efforts that aim to improve urban ecosystem processes. | View Paper |
| Genetic Variation | Neville, Helen & Peterson, Douglas. (2014). Genetic monitoring of trout movement after culvert remediation: Family matters. Canadian Journal of Fisheries and Aquatic Sciences. 71. 1680-1694. 10.1139/cjfas-2014-0138. | We contrasted various genetic analyses to evaluate their utility and constraints for detecting movement of cutthroat trout (Oncorhynchus clarkii) through restored culverts in different field settings: population-level metrics of genetic variability (heterozygosity and allelic richness); Bayesian clustering and assignment of individual genotypes from age 1+ fish; and a novel "sib-split" approach, where movement patterns are extracted from the spatial distribution of young-of-year (YOY) full- sibling groups inferred via pedigree reconstruction. Family structure greatly influenced population-level and individual clustering results in our small headwater populations, even though field sampling was implemented to avoid siblings. Sib-split, which uses family structure to detect movement, uncovered passage of YOY just weeks after emergence. When retrospectively applied to older individuals, it proved essential in interpreting clustering patterns and captured passage in several families of 1- and 2-year-olds. Where family structuring may negatively affect genetic analyses or, alternatively, be prominent enough to allow application of sib-split is difficult to predict a priori; we discuss benefits and limitations of all approaches under different ecological, spatial, and management scenarios | View Paper |
| Species Movement and Dispersal | Newmark, William. (1993). The role and design of wildlife corridors with examples from Tanzania. Ambio. 22. 500-504. | Many protected areas worldwide will be too small to maintain long-term viable populations of many of their resident species. It may be possible in many cases to reduce the adverse "island" effects by linking adjacent protected areas with wildlife corridors. Wildlife corridors are defined in this paper as habitat thatpermits the movement of organisms between ecological isolates. Corridors should be designed for those species within a protected area that are considered to be most vulnerable to extinction. For these species knowledge about the habitat requirements, dispersal, seasonal movements, avoidance behavior, and learning behavior are important for the design of wildlife corridors. The ability of a species to successfully use a corridor is dependent in part upon the width and length of the corridor. In most cases, the determination of the minimum corridor width will be an empirical calculation. Many of the practical challenges of designing wildlife corridors are examined by presenting examples of proposed wildlife corridors in the Eastern Usambara Mountains and on Mount Kilimanjaro in Tanzania. | View Paper |
| Species Movement and Dispersal | Ng, S. J., Dole, J. W., Sauvajot, R. M., Riley, S. P., & Valone, T. J. (2004). Use of highway undercrossings by wildlife in southern California. Biological Conservation, 499-507. | Roads, especially large highways, can have significant impacts on wildlife movement and survival. This is especially true for wide-ranging species, such as mammalian carnivores. Some of these impacts may be mitigated if wildlife can find and utilize passageways under highways. To determine if underpasses and drainage culverts beneath highways are used by wildlife as movement corridors, we monitored 15 such passages near Los Angeles, California using remotely triggered cameras and gypsum track stations. We found that passages were used by a variety of species, including carnivores, mule deer, small mammals, and reptiles. Many types of undercrossings were utilized, indicating that passages beneath highways, even when not originally designed for wildlife, can provide important safe avenues for animals to cross roads. For mammals of conservation concern, including native carnivores and deer, passage dimensions, surrounding habitat, and the extent of human activity were assessed to determine if these factors influenced passage use by these species. Our results show that while many native mammals used passages beneath highways, the presence of suitable habitat on either side of the passage was a particularly important factor predicting use. For deer and coyotes, passage dimensions were also important and should be considered with the presence of suitable habitat when wildlife passages are planned or evaluated. To increase the likelihood of utilization and to help prevent animals from crossing road surfaces, we suggest that simple improvements such as habitat restoration near crossing points and animal-proof fencing that serves to funnel wildlife to passages, can facilitate animal movement between fragmented habitats that are bisected by roads. © 2003 Elsevier Ltd. All rights reserved. | View Paper |
| Species Richness | Nicholls, A.O.; Margules, Christopher R. The design of studies to demonstrate the biological importance of corridors. In: Saunders, D. A.;Hobbs, Richard J. (eds.), editor/s. Nature Conservation 2: The Role of Corridors. Chipping Norton, N.S.W.: Surrey Beatty & Sons; 1991. 49-61. | View Paper | |
| Plant Dispersal | Nicholls, C.I., Parrella, M. & Altieri, M.A. The effects of a vegetational corridor on the abundance and dispersal of insect biodiversity within a northern California organic vineyard. Landscape Ecology 16, 133–146 (2001). | During 1996 and 1997, two adjacent 2.5 has organic vineyard blocks (A and B) were monitored to assess the distributional and abundance patterns of the Western grape leafhopper Erythroneura elegantula Osborn (Homoptera: Cicadellidae) and its parasitoid Anagrus epos Girault (Hymenoptera: Mymaridae), Western flower thrips Frankliniella occidentalis (Pergande) and generalist predators. The main difference between blocks was that block A was cut across by a corridor composed of 65 flowering plant species which was connected to the surrounding riparian habitat, whereas block B had no plant corridor. In both years, leafhopper adults and nymphs and thrips tended to be more numerous in the middle rows of block A and less abundant in border rows close to the forest and corridor where predators were more abundant. The complex of predators circulating through the corridor moved to the adjacent vine rows and exerted a regulatory impact on herbivores present in such rows. In block B all insects were evenly distributed over the field, no obvious density gradient was detected from the edges into the center of the field. Although it is suspected that A. epos depended on food resources of the corridor, it did not display a gradient from this rich flowering area into the middle of the field. Likewise no differences in rates of egg parasitism of leafhoppers could be detected in vines near the corridor or in the vineyard center. The presence of riparian habitats enhanced predator colonization and abundance on adjacent vineyards, although this influence was limited by the distance to which natural enemies dispersed into the vineyard. However, the corridor amplified this influence by enhancing timely circulation and dispersal movement of predators into the center of the field. | View Paper |
| Influencing Animal Behavoir | Orrock, J. L., Danielson, B. J., Burns, M. J., & Levey, D. J. (2003). Spatial ecology of predator-prey interactions: corridors and patch shape influence seed predation. Ecology, 84 (10), 2589-2599. https://doi-org.proxy.lib.duke.edu/10.1890/02-0439 | Corridors that connect patches of disjunct habitat may be promising tools; for mediating the negative impacts of habitat fragmentation, but little is known about how corridors affect ecological interactions. In eight 12-ha experimental landscapes, we examined how corridors affect the impact of invertebrate, rodent, and avian seed predators on pokeweed, Phytolacca americana. Over 13 months in 2000 and 2001, we quantified the effects of patch shape, connectivity, and predator type on the number of seeds germinating in the field (germinants), seed removal, and the viability of remaining seeds. ; Corridors did not affect the number of P. americana germinants in experimental exclosures or the viability of seeds remaining in exclosures. However, corridors affected the removal of seeds in a predator-specific manner: invertebrates removed more seeds in unconnected patches, whereas rodents removed more seeds in connected patches. Seed removal by birds was similar in connected and unconnected patches. Total seed removal by all seed predators was not affected by corridors, because invertebrates removed more seeds where rodents removed fewer seeds, and vice versa. Overall, seed predation signi‚®cantly reduced the number and viability of remaining seeds, and reduced the number of germinants in 2000 but not in 2001. The abundance of naturally occurring P. americana plants in our experimental patches in 2000 decreased with increasing seed removal from exclosures but was not related to viability or germinants in 2000, suggesting that seed removal may shape the distribution and abundance of this species. ; Complementary patterns of seed removal by rodents and invertebrates suggest that corridors alter the effects of these predator taxa by changing the relative amounts of edge and core (nonedge) habitats in a patch. Because invertebrates and rodents do not completely overlap in the seeds they consume, corridors may change predation pressure on seeds that are primarily consumed by one predator type, with potential consequences for the composition of plant and seed predator communities. | View Paper |
| Species Movement and Dispersal | Ortiz-Lozano, L. & Pérez España, Horacio & Granados-Barba, Alejandro & González Gándara, Carlos & Gutiérrez-Velázquez, Ana & Martos, Javier. (2013). The Reef Corridor of the Southwest Gulf of Mexico: Challenges for its management and conservation. Ocean & Coastal Management. 86. 22-32. 10.1016/j.ocecoaman.2013.10.006. | Flow of species and spatial continuity of biological processes between geographically separated areas may be achieved using management tools known as Ecological Corridors (EC). In this paper we propose an EC composed of three highly threatened coral reef systems in the Southwest Gulf of Mexico: Sistema Arrecifal Lobos Tuxpan, Sistema Arrecifal Veracruzano and Arrecifes de los Tuxtlas. The proposed EC is supported by the concept of Marine Protected Areas Networks, which highlights the biogeographical and habitat heterogeneity representations as the main criteria to the establishment of this kind of networks. These three reef systems represent the coral biodiversity of the western Gulf of Mexico. Nevertheless there are serious shortcomings in its protection. Under this approach, the challenges that Mexican government will face for management and conservation of this EC are discussed. There is an obvious lack of an adequate legal framework to establish networks of protected areas in Mexico, mainly because national legislation does not consider connectivity as an important factor in the selection of MPA. | View Paper |
| Population Abundance | Osborne, Megan & Norman, Janette & Christidis, Les & Murray, Neil. (2000). Genetic distinctness of isolated populations of an endangered marsupial, the mountain pygmy-possum, Burramys parvus. Molecular Ecology. 9. 609-13. 10.1046/j.1365-294x.2000.00908.x. | We demonstrate that the social organization and survival rates of the mountain pygmy-possum (Burramys parvus), a rare Australian marsupial, had been disrupted because its habitat had been fragmented by roads and other developments within a ski resort. We restored habitat continuity by constructing a corridor leading to 2 tunnels beneath a road that bisected the breeding area. The corridor and tunnels were filled with rocks that imitated the natural habitat of scree. These constructions allowed males to disperse from the female breeding areas; such dispersal is an essential element in the species social organization. After construction the population structure and survival rates in the disturbed area changed to those observed in the undisturbed area. Our results indicate that wildlife managers should consider that dispersal of individuals plays an important role in the social structure of wildlife populations and corridors and tunnels are strategies available for management of wildlife populations in habitats fragmented by roads and other man-made stuctures. | View Paper |
| Benefits and Consequences For Local Communities | Ostrom, E. (1990). Governing the commons: the evolution of institutions for collective action/Cambridge (p. 1990). New York: Cambridge Univer- sity Press. | Elinor Ostrom's contributions to the understanding self-organization in collective action processes are discussed from a complexity theory perspective. It is argued that complexity researchers can learn from Ostrom¢' theory building process, as well her conceptualization of the conditions of self-organization in the management of common-pool resources. Her focus on self-organization helps rectify the problems with the assumption in the mainstream policy analysis that policy processes can be explained with external causes. The conceptual problems in her utility maximizing rational actor assumption and the potential for conceptual advancements in her recognition of complexity concepts are discussed. It is argued that Ostrom's conceptual framework is sophisticated, but it lacks a dynamic understanding of the micro-macro relationships in complex governance systems, and that complexity theory offers the conceptual tools to remedy this problem. | View Paper |
| Species Movement and Dispersal | Paetkau, D., Vázquez-Domínguez, E., Tucker, N. I. J., & Moritz, C. (2009). Monitoring movement into and through a newly planted rainforest corridor using genetic analysis ofnatal origin. Ecological Management & Restoration , 10 (3), 210–216. | Genetic analysis of individual origins works best with populations that are genetically distinct but which exchange a high rate of immigrants, conditions that don't normally coexist since immigration acts to prevent the accumulation of genetic differences. We provide empirical results from a newly constructed habitat linkage to illustrate the unique suitability of such analysis to monitoring the re-establishment of connections between previously isolated populations. Donaghy's Corridor links a previously isolated 498 ha fragment of rainforest to an adjacent 80 000 ha of intact forest. Starting in the final year of the planting programme that established the corridor, we trapped two species of native small mammals, the Bush Rat (Rattus fuscipes) and the Cape York Rat (Rattus leucopus), within and nearby the linkage. We used genetic data from ear clippings to determine which side of the corridor individual animals originated from, and by comparing this information to trap locations, we identified 16 long-distance movements through the corridor. As genetic analysis of origins allowed movements to be detected from a single capture event and as it reflected movement since birth, this approach yielded considerably more data than capture records alone. The combination of movement and capture records allowed species-specific assessment of corri- dor function, revealing that the use and occupation of the corridor was higher for Bush Rat than for Cape York Rat and was neither symmetrical nor uniform. Long-distance movements through the corridor were most common immediately after habitat restoration, dropping off as the reconstructed habitat was colonized. | View Paper |
| Benefits and Consequences For Local Communities, Species Movement and Dispersal | Paiva, D. S., Guinevere Alvarez Machado De Melo Gomes, Fernández, L., & Andrade, J. C. S. 2014. Voluntary carbon market and its contributions to sustainable development: analysis of the Monte Pascoal-Pau Brazil ecological corridor. International Journal of Innovation and Sustainable Development, 8(1), 1. doi: 10.1504/ijisd.2014.059219 | This paper aims to analyse the co-benefits of reforestation projects developed in the voluntary carbon market based on the analysis of a single case study: the Ecological Corridor Project Monte Pascoal-Pau Brazil, the first forest restoration project in Latin America to receive the seal climate community and biodiversity (CCB). To achieve this purpose, the research combined: i) primary sources, obtained from visits and interviews with key actors and script for semi-structured, with; ii) secondary sources, including reports of institutions on this theme and references. The results presented showed that forestry projects have positive co-benefits beyond those achieved in reducing deforestation and carbon sequestration, whether in environmental and social benefits. The case study had interesting picture of forest governance, growing in transparent structures of popular participation, but has exposed deficiencies in the sector, as the absence of a strong institutional framework, which leads to legal uncertainty and policy. | View Paper |
| Ecosystem Services | Paiva, D. S., Guinevere Alvarez Machado De Melo Gomes, Fernƒ¡ndez, L., & Andrade, J. C. S. (2014). Voluntary carbon market and its contributions to sustainable development: analysis of the Monte Pascoal-Pau Brazil ecological corridor. International Journal of Innovation and Sustainable Development, 8(1), 1. doi: 10.1504/ijisd.2014.059219 | This paper aims to analyse the co-benefits of reforestation projects developed in the voluntary carbon market based on the analysis of a single case study: the Ecological Corridor Project Monte Pascoal-Pau Brazil, the first forest restoration project in Latin America to receive the seal climate community and biodiversity (CCB). To achieve this purpose, the research combined: i) primary sources, obtained from visits and interviews with key actors and script for semi-structured, with; ii) secondary sources, including reports of institutions on this theme and references. The results presented showed that forestry projects have positive co-benefits beyond those achieved in reducing deforestation and carbon sequestration, whether in environmental and social benefits. The case study had interesting picture of forest governance, growing in transparent structures of popular participation, but has exposed deficiencies in the sector, as the absence of a strong institutional framework, which leads to legal uncertainty and policy. | View Paper |
| Species Richness | Pallin, B.N. (2000), Ku‐ring‐gai Flying‐fox Reserve. Ecological Management & Restoration, 1: 10-20. | Strong community support led to gocernment protection of a bat colony in northern Sydney in 1985. Restoration of the roosting habitat of the Grey-headed Flying-fox (Pteropus poliocephalus) was implemented by a non-government organization in cooperation with the local government. The aims, methods, results and challenges of the project so far are outlined. | View Paper |
| Species Movement and Dispersal, Species Richness | Pan, Wenjing & Lin, Liu & Luo, Aidong & Zhang, Li. (2009). Corridor use by Asian elephants. Integrative zoology. 4. 220-31. 10.1111/j.1749-4877.2009.00154.x. | There are 18 km of Kunming-Bangkok Highway passing through the Mengyang Nature Reserve of Xishuangbanna National Nature Reserve in Yunnan Province, China. From September 2005 to September 2006 the impact of this highway on movement of wild Asian elephants between the eastern and western part of the nature reserve was studied using track transecting, rural surveys and direct monitoring. Our results showed that the number of crossroad corridors used by Asian elephants diminished from 28 to 23 following the construction of the highway. In some areas, the elephant activity diminished or even disappeared, which indicated a change in their home ranges. The utilization rate of artificial corridors was 44%. We also found that elephants preferred artificial corridors that were placed along their original corridors. During the research, wild elephants revealed their adaptation to the highway. They were found walking across the highway road surface many times and for different reasons. We suggest that the highway management bureau should revise their management strategies to mitigate the potential risks caused by elephants on the road for the safety of the public and to protect this endangered species from harm. It is also very important to protect and maintain current Asian elephants corridors in this region. | View Paper |
| Species Movement and Dispersal | Pander, Joachim & Müller, Melanie & Geist, Juergen. (2013). Ecological functions of fish bypass channels in streams: Migration corridor and habitat for reophilic species. River Research and Applications. 29. 441-450. 10.1002/rra.1612. | The introduction of weirs into stream ecosystems resulted in modifications of serial continuity and in the decline of riverine fish species. Successful river restoration requires information on the ecological functionality of fish bypass channels that are considered an ecological improvement according to the European Water Framework Directive. In this study, we compared the functionality of three nature-oriented fish passes as compensatory habitats and migration corridors for fishes. Fish passes differed significantly from upstream and downstream reaches of the weirs, revealing higher current speed, lower water depth, smaller channel width and greater habitat variability. Following these structural differences, they provided key habitats for juvenile, small and rheophilic fishes that are typically underrepresented in highly modified water bodies. All fish passes were used as migration corridors, with increased fish movements during high discharge and at spawning periods. Because river stretches with high variability of current speed and water depth are scarce in highly modified water bodies, fish passes can play an important role as compensatory habitats and should thus be considered more intensively in habitat assessments and river restoration. Ideally, fish bypasses should mirror the natural discharge dynamics and consider all occurring fish species and sizes. Copyright © 2011 John Wiley & Sons, Ltd. | View Paper |
| Population Abundance | Pardini, R., de Souza, S. M., Braga-Neto, R., & Metzger, J. P. (2005). The role of forest structure, fragment size and corridors in maintaining small mammal abundance and diversity in an Atlantic forest landscape. Biological conservation, 124(2), 253-266. | Using the abundance and distribution of small mammals at 26 sites in an Atlantic forest landscape, we investigated how species abundance and alpha and beta diversity are affected by fragment size and the presence of corridors. To account for the variability in forest structure among fragments, we described and minimized the influence of foliage density and stratification on small mammal data. Sites were distributed among three categories of fragment size and in continuous forest. For small and medium-sized categories, we considered isolated fragments and fragments connected by corridors to larger remnants. Small mammal abundance and alpha and beta diversity were regressed against site scores from the first axis of a Principal Component Analysis on forest structure variables. Residuals were used in analyses of variance to compare fragment size and connectivity categories. Forest structure influenced total abundance and abundance of some species individually, but not the diversity of small mammal communities. Total abundance and alpha diversity were lower in small and medium-sized fragments than in large fragments and continuous forest, and in isolated compared to connected fragments. Three species were less common, but none was more abundant in smaller fragments. At least one species was more abundant in connected compared to isolated fragments. Beta diversity showed an opposite relationship to fragment size and corridors, increasing in small and isolated fragments. Results highlight the importance of secondary forest for the conservation of tropical fauna, the hyper-dynamism of small isolated fragments and the potential of corridors to buffer habitat fragmentation effects in tropical landscapes. | View Paper |
| Species Richness | Pell, A. (2016). Avian Use of Wildlife Overpass. Griffith University. Queensland, Australia. | Roads and road networks impact negatively on wildlife in a number of ways. Of major importance are vehicle-caused mortality, habitat fragmentation and barriers to animal movement. Together, the last two can lead to functional isolation of faunal populations, which, in turn, can potentially jeopardise the long-term persistence of wildlife populations. Wildlife overpasses are used to mitigate threats associated with the roads they span. Important conservation objectives are to allow safe passage and to maintain levels of dispersal between fragmented habitat areas, thereby allowing gene-flow and sustaining population viability of target species. It might be assumed that birds, having the ability to fly, can accommodate the effects of fragmentation well, and will benefit little from wildlife overpasses. A major objective of my study therefore was to evaluate the conservation value of a wildlife overpass in allowing passage of birds between forest areas bisected by a major road. | View Paper |
| Invasive Species | Pimentel, D., Lach, L., Zuniga, R., & Morrison, D. (2000). Environmental and Economic Costs of Nonindigenous Species in the United States. BioScience, 50(1), 53-65. | Approximately 50,000 non indigenous (non-native) species are estimated to have been introduced to the United States. Some of these are beneficial; for example, species introduced as food crops (e.g., corn, wheat, and rice) and as livestock (e.g., cattle and poultry) now provide more than 98% of the US food system, at a value of approximately $800 billion per year (USBC 1998). Other exotic species have been introduced for landscape restoration, biological pest control, sport, pets, and food processing, also with significant benefits. Some nonindigenous species, however, have caused major economic losses in agriculture, forestry, and several other segments of the US economy, in addition to harming the environment. One study reported that 79 exotic species had caused approximately $97 billion in damages during the period 1906-1991 (OTA 1993). | View Paper |
| Influencing Animal Behavoir | Pimm, S. L., Russell, G. J., Gittleman, J. L., & Brooks, T. M. (1995). The future of biodiversity. Science, 296, 347-350. | Recent extinction rates are 100 to 1000 times their pre-human levels in well-known, but taxonomically diverse groups from widely different environments. If all species currently deemed "threatened" become extinct in the next century, then future extinction rates will be 10 times recent rates. Some threatened species will survive the century, but many species not now threatened will succumb. Regions rich in species found only within them (endemics) dominate the global patterns of extinction. Although new technology provides details of habitat losses, estimates of future extinctions are hampered by our limited knowledge of which areas are rich in endemics. | View Paper |
| Ecosystem Services, Species Movement and Dispersal | Poffenberger, M. (2015). Restoring and Conserving Khasi Forests: A Community-Based REDD Strategy from Northeast India. Forests, 6(12), 4477-4494. doi: 10.3390/f6124382 | An initiative to Reduce Emissions from Deforestation and Forest Degradation (REDD) was launched in December 2007 at the Bali Conference of Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC), yet little progress has been made in Asia in developing certified REDD projects, especially those that engage forest-dependent people. According to UNFCCC, REDD is a multilevel activity that involves both national policy and structures, as well as subnational projects involving local communities [1]. While many Asian nations are trying to create frameworks that link the national strategy to sub-national projects, in India this formal integration has yet to take place. As a consequence projects like the Khasi Hills Community REDD+ project fall outside the UNFCCC strategy and operate under voluntary standards (Plan Vivo) and markets. The project involves both avoided deforestation and reforestation components. The project is being implemented by a federation of ten Khasi tribal kingdoms, a major ethnolinguistic group in the Indian state of Meghalaya. Project experience may provide guidance regarding actions required to create a more enabling environment for community forest carbon projects in Asia. These findings may better inform the December 2015 21st UNFCCC Conference of Parties in Paris as they again address REDD strategy. The experience of this Khasi Federation [2] in designing and implementing a REDD project has led to the emergence of a modernizing forest management system that is helping to conserve and restore the Khasi's ancestral forests. Learning from this REDD project also illustrates the barriers that the Khasi communities have faced, including those imposed by national governments, certifiers, and carbon markets, that will likely constrain the expansion and replication of community-based climate initiatives. The author suggests some alternative policies and systems that may enable greater community participation in REDD projects. | View Paper |
| Species Movement and Dispersal | Poplar-Jeffers, Ira & Petty, Todd & Anderson, James & Kite, J. & Strager, Michael & Fortney, Ronald. (2008). Culvert Replacement and Stream Habitat Restoration: Implications from Brook Trout Management in an Appalachian Watershed, U.S.A.. Restoration Ecology. 17. 404 - 413. 10.1111/j.1526-100X.2008.00396.x. | Large-scale culvert replacement programs could benefit migratory fish populations by reconnecting reproductive and foraging habitats in fragmented watersheds. The objectives of this study were to: (1) identify stream and culvert characteristics contributing to fish passage barriers within an Appalachian watershed, U.S.A.; (2) quantify the total amount of Brook trout (Salvelinus fontinalis) reproductive habitat isolated above culverts; and (3) use an ecological currency to identify culvert replacement priorities and stream mitigation credit opportunities. We surveyed 120 state-owned culverts and used a fish passage assessment filter to determine the "passability" of each culvert. We then constructed a geographic information system stream network model to quantify the amount of trout reproductive habitat isolated by culverts. Ninety-seven percent of surveyed culverts were classified as obstacles or complete barriers to trout dispersal. Culvert impassability was higher in small streams with slopes exceeding 3-5%, suggesting a direct relationship between slope and impassability. Thirty-three percent of Brook trout reproductive habitat, representing over 200 km of stream, was isolated by culverts. This is a conservative estimate, because we did not survey privately or federally owned culverts. The top 20 prioritized culverts accounted for nearly half of the habitat loss. Our results indicate that standard culvert designs placed in streams with slopes exceeding 5% consistently produce trout dispersal barriers and should be avoided during new road construction. The process developed here provides an efficient method for identifying culvert replacement priorities and may be used to maximize watershed scale benefits of stream restoration. | View Paper |
| Invasive Species | Rahel, Frank J., Intentional Fragmentation as a Management Strategy in Aquatic Systems, BioScience, Volume 63, Issue 5, May 2013, Pages 362–372, | Maintaining or restoring connectivity in aquatic systems can enhance migratory fish populations; maintain genetic diversity in small, isolated populations; allow organisms to access complementary habitats to meet life-history needs; and facilitate recolonization after local extirpations. However, intentional fragmentation may be beneficial when it prevents the spread of nonnative species or exotic diseases, eliminates hybridization between hatchery and wild stocks, or stops individuals from becoming entrapped in sink environments. Strategies for fragmenting aquatic systems include maintaining existing natural barriers, taking advantage of existing anthropogenic features that impede movement, severing artificial connectivity created by human actions, and intentionally creating new barriers. Future challenges for managing fragmentation include maintaining hydrologic connectivity while blocking biological connectivity in water development projects; identifying approaches for maintaining incompatible taxa, such as sport fishes and small nongame species; and developing selective barriers that prevent the passage of unwanted species while allowing normal life-history movements of other species. | View Paper |
| Invasive Species, Species Richness | Resasco, Julian & Haddad, Nick & Orrock, John & Shoemaker, Dewayne & Brudvig, Lars & Damschen, Ellen & Tewksbury, Joshua & Levey, Douglas. (2014). Landscape corridors can increase invasion by an exotic species and reduce diversity of native species. Ecology. 95. 2033-2039. 10.1890/14-0169.1. | Landscape corridors are commonly used to mitigate negative effects of habitat fragmentation, but concerns persist that they may facilitate the spread of invasive species. In a replicated landscape experiment of open habitat, we measured effects of corridors on the invasive ?re ant, Solenopsis invicta, and native ants. Fire ants have two social forms: polygyne, which tend to disperse poorly but establish at high densities, and monogyne, which disperse widely but establish at lower densities. In landscapes dominated by polygyne ?re ants, ?re ant abundance was higher and native ant diversity was lower in habitat patches connected by corridors than in unconnected patches. Conversely, in landscapes dominated by monogyne ?re ants, connectivity had no in?uence on ?re ant abundance and native ant diversity. Polygyne ?re ants dominated recently created landscapes, suggesting that these corridor effects may be transient. Our results suggest that corridors can facilitate invasion and they highlight the importance of considering species' traits when assessing corridor utility. | View Paper |
| Influencing Animal Behavoir | Robert, J. B., Haddad, N. M., & Orrock, J. L. (2005). Corridors and olfactory predator cues affect small mammal behavior. Journal of Mammalogy, 86(4), 662-669. 3. Weldon, A. J. (2006). How corridors reduce Indigo Bunting Nest Success. Conservation Biology. | The behavior of prey individuals is influenced by a variety of factors including, but not limited to, habitat configuration, risk of predation, and availability of resources, and these habitat-dependent factors may have interactive effects. We studied the responses of mice to an increase in perceived predation risk in a patchy environment to understand how habitat corridors might affect interactions among species in a fragmented landscape. We used a replicated experiment to investigate corridor-mediated prey responses to predator cues in a network of open habitat patches surrounded by a matrix of planted pine forest. Some of the patches were connected by corridors. We used mark-recapture techniques and foraging trays to monitor the movement, behavior, and abundance of small mammals. Predation threat was manipulated in one-half of the replicates by applying an olfactory predator cue. Corridors synchronized small mammal foraging activity among connected patches. Foraging also was inhibited in the presence of an olfactory predator cue but apparently increased in adjacent connected patches. Small mammal abundance did not change as a result of the predator manipulation and was not influenced by the presence of corridors. This study is among the 1st to indicate combined effects of landscape configuration and predation risk on prey behavior. These changes in prey behavior may, in turn, have cascading effects on community dynamics where corridors and differential predation risk influence movement and patch use. | View Paper |
| Population Abundance, Species Movement and Dispersal | Rosenberg, D. K., Noon, B. R., & Meslow, E. C. (1997). Biological corridors: form, function, and efficacy. BioScience, 47(10), 677-687. | Habitat loss and fragmentation are among the most pervasive threats to the conservation of biological diversity (Wilcove et. al.. 1986, Wilcox and Murphy 1985). Habitat fragmentation often leads to the isolation of small populations, which have higher extinction rates (e.g., Pimmet. al.. 1988). Ultimately, the processes of isolation and population extinction lead to a reduction in biological diversity. Concern for this loss has motivated conservation biologists to discuss the actions that are needed to increase the effective size of local populations. Predominant among these possible strategies has been the recommendation that corridors be included in conservation plans (Figure 1)to increase the connectivity of otherwise isolated patches (Meffe and Carroll 1994). | View Paper |
| Species Richness | Roush, G. J. (1985). The heritage concept entering the second decade. Natural Conservation News, 35, 5-11. | n/a | |
| Species Movement and Dispersal | Samways, Michael & Bazelet, Corinna & Pryke, James. (2010). Provision of ecosystem services by large scale corridors and ecological networks. Biodiversity and Conservation. 19. 2949-2962. 10.1007/s10531-009-9715-2. | Large scale landscape transformation and contingent habitat loss are among the greatest threats to ecological integrity and ecosystem health. One of the mitigation approaches used to deal with these pressures is to leave interconnected corridors and nodes as remnant ecological networks (ENs) within the transformed landscape. The South African forestry industry has already allocated 500,000 ha, one-third of the plantation holdings, consisting predominantly of natural grassland, as ENs among and within timber plantations. These ENs are intended to maintain structural, compositional and functional biodiversity. However, little scientific research is available on the effectiveness of these huge ENs for biodiversity conservation and maintenance of natural ecosystem function, although initial findings are encouraging. While the local adverse effect of alien plantation trees on functional biodiversity is not in dispute, it is at the scale of the whole landscape where there is much interest in determining how effective these ENs are in maintaining the untransformed portion of the transformed landscape in a close-to-natural state. As these ENs are extensive, species beta diversity is a consideration in addition to alpha diversity. Initial findings reveal diminished ecological integrity in narrow corridors due in part to the adverse edge effect from the alien trees into the margin of the EN. Quality of the ENs is of great importance for maintaining functional diversity, with human disturbance reducing their effectiveness. First findings, and their application to the Framework for Ecosystem Service Provision, suggest that these ENs are significant for biodiversity conservation and for provision of ecosystem services. Nevertheless, still much more research is required on a greater range of taxa, and their interactions, to improve the design of these ENs for ecological and evolutionary processes. | View Paper |
| Population Abundance | Sanderson, James. Biodiversity Conservation Corridors. Conservation International, Center For Applied Biodiversity Science, 2003. | Our natural world is on the verge of a profound loss of biological diversity. Over the last 400 years approximately 250 species of birds, mammals, reptiles, and amphibians have gone extinct as a result of human activities. With the known anthropogenic extinctions before 1600, this number rises to more than 2,000 (Steadman 1995). Today, an additional 11,167 species of plants and animals are considered threatened, at risk of the same final fate (Hilton-Taylor 2002). | View Paper |
| Species Movement and Dispersal | Sandra Jean Wildlife use of underpasses and culverts crossing beneath highways in Southern California | High-speed roadways are major barriers to animal movement. Underpasses and culverts beneath roadways have been assumed to serve as corridors for wildlife, but few data are available documenting this. I monitored animal use of fifteen crossings beneath three major highways near Los Angeles, California. I found that carnivores, raccoons, skunks, opossums, mule deer, several domesticated animals, and a variety of other species used the corridors. No significant correlations were found between predictor variables (passage length, cross-sectional area, percentages of developed and wild habitats, human activity) and carnivore use. In contrast, corridor use by raccoons alone and by raccoons combined with other medium-sized mammals was positively correlated with surrounding developed habitat. Deer use was significantly associated with both the length and the cross-sectional area of the passages. These results verify that many animals do use these corridors, and the nature of the surrounding habitat and of the passage attributes are critical in determining which animals use them. Road kill surveys conducted along the same highways demonstrated that the number of road kills is inversely associated with traffic volume and that large wild mammals are most commonly killed along highways bordered by open areas whereas raccoons and other medium-sized wild mammals are most commonly killed near developed areas. | View Paper |
| Species Movement and Dispersal | Saura, Santiago & Gurrutxaga, Mikel. (2013). Prioritizing highway defragmentation locations for restoring landscape connectivity. Environmental Conservation. 41. 10.1017/S0376892913000325. | Transport infrastructures are a major driver of global landscape change. In many areas, highways were built before environmental impact assessments required the implementation of wildlife crossing structures. A fundamental task in the development of ecological networks is identifying areas where dispersal pathways of vulnerable populations may be blocked or affected by high volume roads. Financial considerations may limit investment, thus it is vital to establish the relative contribution of each road defragmentation location to upholding habitat connectivity and availability. In this paper, recent methodological developments in habitat network analysis, derived from the probability of connectivity index, were refined and used to evaluate the role of each highway defragmentation location in restoring landscape connectivity. The forest protected area network in the Basque country (northern Spain) was selected as an illustrative case study. The proposed approach was able to quantify and effectively account for a combination of factors determining the contribution of each highway defragmentation location to upholding connectivity, which are rarely jointly considered in analyses oriented to support restoration decisions in landscapes affected by the barrier effect of transport infrastructures. The contribution to connectivity of each defragmentation location depended on its topological position in the landscape, on the relative decrease in the effective distance among habitat areas that results from the permeability restoration at that location, on the distance from the defragmentation location to other alternative wildlife crossing structures already existing in the landscape, on the amount of habitat in the areas connected by the linkages that run through the defragmentation location and on the dispersal abilities of the focal species. | View Paper |
| Genetic Variation | Sawaya, Michael A., Steven T. Kalinowski, and Anthony P. Clevenger. "Genetic connectivity for two bear species at wildlife crossing structures in Banff National Park." Proceedings of the Royal Society B: Biological Sciences 281.1780 (2014): 20131705. | Roads can fragment and isolate wildlife populations, which will eventually decrease genetic diversity within populations. Wildlife crossing structures may counteract these impacts, but most crossings are relatively new, and there is little evidence that they facilitate gene flow. We conducted a three-year research project in Banff National Park, Alberta, to evaluate the effectiveness of wildlife crossings to provide genetic connectivity. Our main objective was to determine how the Trans-Canada Highway and crossing structures along it affect gene flow in grizzly (Ursus arctos) and black bears (Ursus americanus). We compared genetic data generated from wildlife crossings with data collected from greater bear populations. We detected a genetic discontinuity at the highway in grizzly bears but not in black bears. We assigned grizzly bears that used crossings to populations north and south of the highway, providing evidence of bidirectional gene flow and genetic admixture. Parentage tests showed that 47% of black bears and 27% of grizzly bears that used crossings successfully bred, including multiple males and females of both species. Differentiating between dispersal and gene flow is difficult, but we documented gene flow by showing migration, reproduction and genetic admixture. We conclude that wildlife crossings allow sufficient gene flow to prevent genetic isolation. | View Paper |
| Species Movement and Dispersal | Schroder, Mellesa and Sato, Chloe F. 2017, An evaluation of small-mammal use of constructed wildlife crossings in ski resorts, Wildlife Research, vol. 44, no. 3, pp. 259-268, doi: 10.1071/WR16102. | Infrastructure development in ski-resort areas has led to the modification of slopes and, often, the replacement of native plant species with exotic grasses. Modified ski slopes are effectively linear areas of disturbance that separate natural habitat and provide barriers to the movement of native animal species. To overcome these barriers, boulder-filled and culvert-style wildlife crossings have been constructed across disturbed ski slopes and under roadways to facilitate the movement of small native mammal species among areas of remnant habitat, but generally they differ in size and locality. The use of boulder-filled and under-road culvert crossings of different length has not been evaluated. Aims We determine whether fauna utilise wildlife crossings in ski resorts and whether variations in crossing length influence the species using the crossings. Methods We monitored boulder-filled crossings of two size classes (long or short) biannually from March 2009 to April 2013, using hair tubes. We monitored an additional two under-road culvert crossings with remote infrared cameras. Key results The results indicated that all crossings, regardless of size, are utilised by small mammals. However, we detected threatened species, such as Mastacomys fuscus (broad-toothed rat), more frequently in crossings of greater length. Conclusions To maintain linkages for small-mammal populations within ski resorts, we recommend the continued use of boulder-filled crossings on ski slopes. These crossings may be particularly important in facilitating the movement of small mammals across wide areas of ski-slope disturbance. Implications The context and maintenance of crossings is likely to be important for their long-term use by small mammals, as are complementary strategies to restore structural habitat connectivity on ski slopes, such as strategically implemented native vegetation plantings. | View Paper |
| Species Movement and Dispersal | Schultz, C. B. 1998. Dispersal behavior and its implications for reserve design in a rare Oregonbutterfly. Conservation Biology , 12, 284–292. | To identify reserve design strategies for an endangered species, we need to understand the dispersal behavior of the species. For example, constructing corridors for an endangered species makes sense only if that species remains in its primary habitat and rarely strays into adjoining areas. I investigated the dispersal behavior of the Fender's blue butterfly (Icaricia icarioides fenderi) to assess possible reserve designs for it. The Fender's blue is a rare butterfly that survives in 13 remnants of upland prairie in the Willamette Valley in Oregon. I observed butterfly flight patterns in primary lupine habitat, in nearby abandoned fields, and at the boundaries between the habitats. Observations indicate that, on an individual basis, the butterflies weakly bias their movements toward lupine areas; on a population basis, however, more than 95% are found within 10 m of lupine patches. These observations imply that although the Fender's blue is usually found in lupine patches, they stray into nonlupine areas frequently enough to call into question the effectiveness of a corridor. Butterfly flight paths were mapped in lupine and nonlupine areas to determine how their rates of spread depended on the habitat in which they were found. Butterflies within lupine areas dispersed at relatively slow rates (<3 m Butterfly flight paths were mapped in lupine and nonlupine areas to determine how their rates of spread depended on the habitat in which they were found. Butterflies within lupine areas dispersed at relatively slow rates (<3 m Butterfly flight paths were mapped in lupine and nonlupine areas to determine how their rates of spread depended on the habitat in which they were found. Butterflies within lupine areas dispersed at relatively slow rates (<3 m2 / s), whereas those flying outside lupine areas disperse much more rapidly (> 15 m 2/ s). Observations of daily activity patterns suggest that the butterflies fly about 2.3 hours a day, and a mark ‐ recapture ‐ release experiment indicates that butterflies live about 9.5 days. I used the estimates of diffusion and total flight time to suggest the range Fender's blue butterflies disperse in their lifetime. I estimate that a Fender's blue might disperse about 0.75 km in its lifetime if it remains in lupine habitat but more than 2 km if it disperses between lupine patches. Historically, the Willamette Valley was a mosaic of upland and wetland prairie, with lupine patches rarely more than 0.5 km apart. At that time, the Fender's blue would have had a high probability of dispersing between patches. Today, however, lupine patches are isolated, with 3–30 km between patches. Thus, it is extremely unlikely that dispersing butterflies find new patches when they leave their natal lupine patch. Dispersal observations suggest that stepping stones between existing patches may be more effective than corridors at facilitating the exchange of individuals. | View Paper |
| Species Movement and Dispersal | Schultz, Cheryl & CRONE, ELIZABETH. (2005). Patch Size and Connectivity Thresholds for Butterfly Habitat Restoration. Conservation Biology. 19. 887 - 896. 10.1111/j.1523-1739.2005.00462.x. | Recovery of endangered species in highly fragmented habitats often requires habitat restoration. Selection of restoration sites typically involves too many options and too much uncertainty to reach a decision based on existing reserve design methods. The Fender's blue butterfly (Icaricia icarioides fenderi) survives in small, isolated patches of remnant prairie in Oregon's Willamette Valley - a habitat for which <0.5% of the original remains. Recovery of this species will require considerable habitat restoration. We investigated the potential of biologically based rules of thumb and more complex models to serve as tools in making land acquisitions. Based on Fender's blue dispersal behavior and demography, we have estimated that restored patches should be <1 km from existing habitat and at least 2 ha. We compared these rules to the results of two modeling approaches: an incidence function model and a spatially explicit simulation of demography and dispersal behavior. Not surprisingly, the simple rules and complex models all conclude that large (>2 ha) connected (<1 km) patches have the highest restoration value. The dispersal model, however, suggests that small, connected patches have more restoration value than large, isolated patches, whereas the incidence function model suggests that size and connectivity are equally important. These differences stem from model assumptions. We used incidence functions to predict long-term, stochastic, steady-state conditions and dispersal simulations to predict short-term (25-year) colonization dynamics. To apply our results in the context of selecting restoration sites on the ground, we recommend selecting nearby sites when short-term colonization dynamics are expected to be an important aspect of a species' biology. | View Paper |
| Species Richness | Seip, C., Hodder, D., Crowley, S., & Johnson, C. (2018). Use of constructed coarse woody debris corridors in a clearcut by American martens (Martes americana) and their prey. Forestry, 91(4), 506-513. | American martens (Martes americana) are typically associated with mature coniferous forests because they provide overhead cover and coarse woody debris (CWD) that martens require for protection and hunting. Therefore, clearcuts are considered poor marten habitat because they contain no overhead cover and relatively little CWD. We examined the efficacy of retaining CWD and constructing CWD corridors in a recently harvested clearcut to promote the use of the area by martens and small mammals, a major prey resource. We installed remote cameras in corridors, the surrounding clearcut and forest to monitor the distribution of martens and small mammals. Martens and red squirrels did not use CWD corridors more frequently than clearcut areas in summer; forest-floor small mammals, however, used corridors approximately three times as frequently as other habitats (x2 = 13.374, P = 0.001). Marten presence was positively associated with mature, dense forest and long pieces of CWD. In winter, red squirrels used corridors more frequently than other clearcut areas, and limited data suggested that martens preferred the corridors to other clearcut areas. Consequently, we recommend that forest managers retain CWD and construct CWD corridors within clearcuts to provide small mammal habitat, and to enhance marten habitat. | View Paper |
| Species Movement and Dispersal | Selonen, V., & Hanski, I. K. (2003). Movements of the flying squirrel Pteromys volans in corridors and in matrix habitat. Ecography, 26(5), 641-651 | Elements of the landscape, such as patches of preferred habitat, matrix between patches, and corridors linking patches, differ as movement habitat for animals. To understand how landscape structure influences the movement and thus, population dynamics of animals, clear empirical knowledge on patterns of movement is needed. The Siberian flying squirrel inhabits spruce-dominated boreal forests from Finland to eastern Siberia. Numbers of flying squirrels have declined severely in Finland in past decades, probably due to modern forestry. We studied the movement of radio-collared adult flying squirrels in preferred (spruce forest) and in matrix habitat (open areas and other habitats with trees) in Finland 1997-2000, and determined whether the woodland strips connecting patches of preferred habitat could function as ecological corridors for flying squirrels. Flying squirrels used woodland strips for inter-patch movements, but also used matrix with trees and were able to cross narrow open gaps. Males moved longer total distances and crossed edges more often than females. Males used matrix habitats for movement between spruce patches, and moved faster and more directly in the matrix than in the spruce forest. Females seldom changed spruce patches, but instead used the matrix for foraging. For both sexes probability of leaving the spruce forest patch correlated negatively with the size of the patch, but the type of connection the patch had to other patches did not affect the leaving probability. Due to efficient movement abilities of the flying squirrel and forest-dominated landscape structure of southern Finland, we suggest that conservation acts for maintaining viable populations of flying squirrels should focus on the quality of managed forest and the area of suitable breeding habitat (i.e. on habitat loss), but not necessarily on ecological corridors. | View Paper |
| Genetic Variation | Sharma, Sandeep & Dutta, Trishna & Maldonado, Jesús & Wood, Thomas & Panwar, Hemendra & Seidensticker, John. (2014). Sharma et al - Forest corridors maintain historical gene flow in a tiger metapopulation in the highlands of central India. - Proc Royal Society B. | Understanding the patterns of gene flow of an endangered species metapopulation occupying a fragmented habitat is crucial for landscape-level conservation planning and devising effective conservation strategies. Tigers (Panthera tigris) are globally endangered and their populations are highly fragmented and exist in a few isolated metapopulations across their range. We used multi-locus genotypic data from 273 individual tigers (Panthera tigris tigris) from four tiger populations of the Satpura-Maikal landscape of central India to determine whether the corridors in this landscape are functional. This 45 000 km2 landscape contains 17% of India's tiger population and 12% of its tiger habitat. We applied Bayesian and coalescent-based analyses to estimate contemporary and historical gene flow among these populations and to infer their evolutionary history. We found that the tiger metapopulation in central India has high rates of historical and contemporary gene flow. The tests for population history reveal that tigers populated central India about 10 000 years ago. Their population subdivision began about 1000 years ago and accelerated about 200 years ago owing to habitat fragmentation, leading to four spatially separated populations. These four populations have been in migration-drift equilibrium maintained by high gene flow. We found the highest rates of contemporary gene flow in populations that are connected by forest corridors. This information is highly relevant to conservation practitioners and policy makers, because deforestation, road widening and mining are imminent threats to these corridors. | View Paper |
| Species Movement and Dispersal | Shepherd, Brenda, and Jesse Whittington. “Response of Wolves to Corridor Restoration and Human Use Management.” Ecology and Society, vol. 11, no. 2, 2006. | Corridor restoration is increasingly being used to connect habitat in mountainous areas where rugged topography and increasing human activity fragment habitat. Wolves (Canis lupus) are a conservation priority because they avoid areas with high levels of human use and are ecologically important predators. We examined how corridor restoration through a golf course changes the distribution of wolves and their prey in Jasper National Park, Alberta, Canada. We followed and recorded wolf paths in the snow both within the corridor and in the surrounding landscape before and after a corridor was re-established. Track transects were used to estimate prey abundance and snow depths, and trail counters measured human activity. We compared resources on wolf paths to available movement routes using conditional logistic regression and also compared resources used by wolves before and after restoration. We addressed potential confounding effects of prey abundance, snow depths, and levels of human use by testing for changes in these variables. Prior to restoration, wolves traveled around the golf course and used the mountainside to connect valley-bottom habitat. Conversely, elk (Cervus elaphus) densities were highest in the golf course. After restoration, wolves shifted most of their movement to the golf course corridor, whereas elk dispersed along the corridor and mountainside. When traveling through the study area, wolves selected for areas with high prey abundance, low elevations, and low levels of human activity. Corridor restoration increased the area of high quality habitat available to wolves and increased their access to elk and deer at low elevations. Our results corroborate other studies suggesting that wolves and elk quickly adapt to landscape changes and that corridor restoration can improve habitat quality and reduce habitat fragmentation. | View Paper |
| Invasive Species | Simberloff, D., & Cox, J. (1987). Consequences and Costs of Conservation Corridors. Conservation Biology, 1(1), 63-71. | There are few controlled data with which to assess the conservation role of corridors connecting refuges. If cor-ridors were used sufficiently, they could alleviate threats from inbreeding depression and demographic stochasticity. For species that require more resources than are available in single refuges, a network of refuges connected by corridors may allowpersistence. Finally, a cowidor, such as a riparian foresc may constitute an important habitat in its own right. A dearth of information on the degree to which different species use corridors makes it difficult to tell which of these potential advantages will be realized in any particular case. Some experimental field studies suggest that certain species will use corridors, although lack of controls usually pre-cludes a firm statement that cowidors will prevent extinc-tion. | View Paper |
| Species Movement and Dispersal | Simberloff, D., Farr, J. A., Cox, J., & Mehlman, D. W. (1992). Movement Corridors: Conservation Bargains or Poor Investments? Conservation Biology, 6(4), 493-504. | There are few controlled data with which to assess the conservation role of corridors connecting refuges. If corridors were used sufficiently, they could alleviate threats from inbreeding depression and demographic stochasticity. For species that require more resources than are available in single refuges, a network of refuges connected by corridors may allow persistence. Finally, a cowidor, such as a riparian foresc may constitute an important habitat in its own right. A dearth of information on the degree to which different species use corridors makes it difficult to tell which of these potential advantages will be realized in any particular case. Some experimental field studies suggest that certain species will use corridors, although lack of controls usually precludes a firm statement that cowidors will prevent extinction. | View Paper |
| Species Movement and Dispersal | Simms, Anthony & Moheb, Zalmai & Salahudin, & Ali, Hussain & Ali, Inayat & Wood, Timothy. (2011). Saving threatened species in Afghanistan: Snow leopards in the Wakhan Corridor. International Journal of Environmental Studies. 68. 299-312. 10.1080/00207233.2011.577147. | The Wakhan Corridor in northeast Afghanistan is an area known for relatively abundant wildlife and it appears to represent Afghanistan's most important snow leopard landscape. The Wildlife Conservation Society (WCS) has been working in Wakhan since 2006. Recent camera trap surveys have documented the presence of snow leopards at 16 different locations in the landscape. These are the first camera trap records of snow leopards in Afghanistan. Threats to snow leopards in the region include the fur trade, retaliatory killing by shepherds and the capture of live animals for pets. WCS is developing an integrated management approach for this species, involving local governance, protection by a cadre of rangers, education, construction of predator-proof livestock corrals, a livestock insurance program, tourism and research activities. This management approach is expected to contribute significantly to the conservation of snow leopards and other wildlife species in the Wakhan. | View Paper |
| Species Movement and Dispersal | SIMPSON, NOVA O., et al. “Overpasses and Underpasses: Effectiveness of Crossing Structures for Migratory Ungulates.” The Journal of Wildlife Management, vol. 80, no. 8, 2016, pp. 1370–1378., www.jstor.org/stable/44132785. Accessed 16 Apr. 2021. | Maintenance of movement corridors is a fundamental component of the conservation of biological diversity, and is especially critical for terrestrial species that migrate extended distances. Highways and interstate freeways fragment corridors and often result in increased mortality of terrestrial migrants from collisions with vehicles. Wildlife crossing structures are an important tool in multiple ecosystems to allow safe passage for wildlife across roadways. Indeed, crossing structures have been used extensively in Europe and with increasing frequency in North America to reconnect fragmented habitats for numerous species. Few projects, however, have documented responses to >1 structure type simultaneously that are close to one another. We used mule deer (Odocoileus hemionus), a widespread species across diverse bioregions in western North America, to test hypotheses about efficacy of 2 different types of crossing structures for ungulates. We documented behavioral responses and use of overpasses and underpasses by mule deer. Our metrics to evaluate success included passage rates and the number of animals that crossed each structure. Crossing structures were used by mule deer immediately following construction and although all of the crossing structures were used, we observed greater passage rates at overpasses than underpasses. Wildlife crossing structures reduced habitat fragmentation and enhanced connectivity by allowing safe passage across US 93. More importantly, those structures succeeded in removing a large number of mule deer from the roadway making US 93 safer for wildlife and motorists. © 2016 The Wildlife Society. | View Paper |
| Species Movement and Dispersal | Sinclair, Kristen & Hess, George & Moorman, Christopher & Mason, Jamie. (2005). Mammalian nest predators respond to greenway width, landscape context and habitat structure. Landscape and Urban Planning. 71. 277-293. 10.1016/j.landurbplan.2004.04.001. | Birds of conservation concern breed in suburban greenways, yet abundant populations of mammals that depredate bird nests might reduce nest success. We evaluated how three factors influenced the abundance of mammalian nest predators in thirty-four 300-m long forested greenway segments in Raleigh and Cary, North Carolina, USA: (1) the width of the forested corridor containing the greenway, (2) the land-use adjacent to the forested corridor, and (3) the habitat structure within the greenway. Forest corridor width and adjacent land-use were measured using aerial photographs. Attributes of adjacent land use included categorical measures of development intensity (low-density residential, high-density residential, office/institutional), and the proportions of forest canopy, grass, buildings, and pavement. Several measures of habitat structure within the greenway were collected in the field, including trail width and surface type, and percentage of mature forest. We measured the relative abundance of mammalian nest predators with scent-station transects, operated for five nights during the 2002 breeding bird season. | View Paper |
| Species Movement and Dispersal, Genetic Variation | Soanes, Kylie, et. al.. "Evaluating the success of wildlife crossing structures using genetic approaches and an experimental design: lessons from a gliding mammal." Journal of Applied Ecology 55.1 (2018): 129-138. | Millions of dollars are spent on wildlife crossing structures intended to reduce the barrier effects of roads on wildlife. However, we know little about the degree to which these structures facilitate dispersal and gene flow. Our study incorporates two elements that are rarely used in the evaluation of wildlife crossing structures: an experimental design including a before and after comparison, and the use of genetic techniques to demonstrate effects on gene flow at both population and individual levels. We evaluated the effect of wildlife crossing structures (canopy bridges and glider poles) on a gliding mammal, the squirrel glider (Petaurus norfolcensis). We genotyped 399 individuals at eight microsatellite markers to analyse population structure, first?generation migrants and parentage relationships. Installing a crossing structure at the location with a strong barrier effect restored gene flow within just 5 years of mitigation. Synthesis and applications. Our study highlights the importance of using genetic techniques not just to evaluate the success of road?crossing structures for wildlife, but also to guide their placement within the landscape. Managers wishing to reduce the effects of linear infrastructure on squirrel gliders and other arboreal mammals should aim to preserve and enhance vegetation along roadsides and within centre medians, as well as mitigate large gaps by implementing wildlife crossing structures. | View Paper |
| Species Movement and Dispersal | Soule, M. E., and M. E. Gilpin. 1991. The theory of wildlife corridor capability. Pages 3–8 in D. A. Saunders and R. J. Hobbs, editors. Nature conservation 2: the role of corridors. Surrey Beatty and Sons, Chipping Norton, Australia. | Decisions about the identity of the species for which the corridor is designed must be made early in the analysis. Corridor capability analysis depends on a thorough grasp of the life history and demography of the candidate species. The potential benefits of corridors for specific species must be weighed against the potential detrimental effects for the ecosystems as wholes. A computer simulation of corridor capability for animals suggested: 1) optimum corridor width depends on the strength of the edge effect - the higher the relative mortality rate of the edge, the wider the corridor must be; 2) any departures from linearity, even for relatively intelligent animals, may be deleterious; and 3) the shape of corridors may be important. | View Paper |
| Species Movement and Dispersal | Stuart J. Little, Robert G. Harcourt, Anthony P. Clevenger, Do wildlife passages act as prey-traps?, Biological Conservation, Volume 107, Issue 2, 2002,Pages 135-145, ISSN 0006-3207. | A number of studies have proposed that wildlife passages beneath roads and railway lines might be exploited by mammalian predators as prey-traps with prey-species being effectively funnelled into areas of high concentration. This proposition has raised the possibility that use of passages by predators may reduce the effectiveness of passages in conserving other forms of wildlife. We review the literature and conclude that evidence for the existence of prey-traps is scant, largely anecdotal and tends to indicate infrequent opportunism rather than the establishment of patterns of recurring predation. Most passage studies record no evidence of predation in or around passages. Conversely, there is some evidence that predator species use different passages than their prey. | View Paper |
| Species Movement and Dispersal | Sutcliffe, Odette & Thomas, Chris. (1996). Open Corridors Appear to Facilitate Dispersal by Ringlet Butterflies (Aphantopus hyperantus) between Woodland Clearings. Conservation Biology - CONSERV BIOL. 10. 1359-1365. 10.1046/j.1523-1739.1996.10051359.x. | We studied the ringlet butterfly (Aphantopus hyperantus) in an area of woodland in eastern England. A hyperantus occurs in open fields, rides (grassy tracks), and glades within the woodland. Mark-recapture methods showed that exchange rates of adult A. hyperantus between fields and glades can be predicted better by distance-via-rides than by direct distance. Behavioral observations showed that A. hyperantus readily moved from glades into rides but rarely moved from glades into dense woodland. The rides are likely to be corridors that act as conduits between fields and glades. In the A. hyperantus system, connectivity could reduce local extinctions and increase rates of recolonization in the event of local extinction. | View Paper |
| Species Movement and Dispersal | Taylor, Brendan & Goldingay, Ross. (2012). Restoring Connectivity in Landscapes Fragmented by Major Roads: A Case Study Using Wooden Poles as “Stepping Stones” for Gliding Mammals. Restoration Ecology. 20. 10.1111/j.1526-100X.2011.00847.x. | Tree-dwelling mammals may be vulnerable to road mortality if forced to cross canopy gaps on the ground. This group of mammals has received scant attention world- wide despite major road projects potentially causing severe fragmentation to their habitat. Gliding mammals may be enabled to cross road gaps that exceed their gliding capability by the installation of tall wooden poles to act as "stepping stones." We investigated whether such glide poles installed across two land-bridges in eastern Australia could restore landscape connectivity for small gliding petaurid marsupials. Hair-traps revealed repeated use of all poles at both locations over periods of 1-3 years. Camera traps at one site suggest a crossing frequency on the poles by the squirrel glider (Petaurus norfolcensis) of once every 3.8 nights. Radio-tracked animals did not glide directly over the road but instead used the poles to cross on the bridge. Hair-traps and camera traps installed within the middle of two reference land-bridges that lacked glide poles failed to detect crossings by gliding mammals despite their presence in adjacent forest. These observations suggest that glide poles can facilitate road crossing and thereby restore habi- tat connectivity for gliding mammals. This lends support to the notion that glide poles have the potential to mitigate road-induced habitat fragmentation for gliding mammals worldwide. | View Paper |
| Species Movement and Dispersal, Species Richness | Taylor, S., Stow, N., Hasler, C., & Robinson, K Terry Fox Drive wildlife guide system intended to reduce road kills and aid the conservation of Blanding's Turtle. Proceedings of the Transportation Association of Canada, 2. | This article investigates the effectiveness of wildlife-only culvert installations along Terry Fox Drive. The road endangers a variety of species including the Blanding's turtle. Their results reveal that the Wildlife Guide System method is effective in mitigating the adverse effects of the road on this endangered species. | View Paper |
| Species Movement and Dispersal, Benefits and Consequences For Local Communities | Teixeira, Fernanda & Printes, Rodrigo & Fagundes, João & Alonso, André & Kindel, Andreas. (2013). Canopy bridges as road overpasses for wildlife in urban fragmented landscapes. Biota Neotropica. 13. 117-123. 10.1590/S1676-06032013000100013. | The effects of habitat fragmentation and deforestation are exacerbated by some elements, such as roads and power lines, which may become filters or barriers to wildlife movements. In order to mitigate mortality and restore connectivity, wildlife passages are being constructed as linear corridors. The installation of these mitigation measures must be followed by systematic monitoring, in order to evaluate their use and effectiveness, to assist in their management, and to convince stakeholders of their value. In this paper we present the results of a monitoring study of the use of rope overpasses developed near a protected area in Porto Alegre, southern Brazil. The canopy bridges were installed by the Urban Monkeys Program in places where electric hazards and road-kills of brown howler monkeys (Alouatta guariba clamitans Cabrera, 1940) were recorded. Camera traps were installed at each bridge, and local people were selected and trained to monitor overpass use over 15 months, from August 2008 to October 2009. Three species were recorded using canopy bridges: brown howler monkey (Alouatta guariba clamitans Cabrera, 1940), white-eared opossum (Didelphis albiventris Lund, 1840) and porcupine (Sphiggurus villosus Cuvier, 1823). Rope bridges with the highest number of species recorded had more forest cover and lower urban area around them than overpasses little used. Our results indicate that overpasses, in Porto Alegre, work as a linear corridor between forest remnants, although the outcomes for individual survival, group persistence, population demography or gene flow have not been measured. Furthermore, canopy bridges may be important to mitigate the impact of roads and power lines on wildlife, but electric cables also need to be completely isolated when present, to warrant animals' physical integrity. | View Paper |
| Species Movement and Dispersal, Ecosystem Services, Plant Dispersal, Population Abundance, Invasive Species | Tewksbury et. al.. (2002). Corridors Tewksbury, J. J., Levey, D. J., Haddad, N. M., Sargent, S., Orrock, J. L., Weldon, A., ... & Townsend, P. (2002). Corridors affect plants, animals, and their interactions in fragmented landscapes. Proceedings of the national academy of sciences, 99(20), 12923-12926. | Among the most popular strategies for maintaining populations of both plants and animals in fragmented landscapes is to connect isolated patches with thin strips of habitat, called corridors. Corridors are thought to increase the exchange of individuals between habitat patches, promoting genetic exchange and reducing population fluctuations. Empirical studies addressing the effects of corridors have either been small in scale or have ignored confounding effects of increased habitat area created by the presence of a corridor. These methodological difficulties, coupled with a paucity of studies examining the effects of corridors on plants and plant-animal interactions, have sparked debate over the purported value of corridors in conservation planning. We report results of a large-scale experiment that directly address this debate. In eight large-scale experimental landscapes that control for patch area and test alternative mechanisms of corridor function, we demonstrate that corridors not only increase the exchange of animals between patches, but also facilitate two key plant-animal interactions: pollination and seed dispersal. Our results show that the beneficial effects of corridors extend beyond the area they add, and suggest that increased plant and animal movement through corridors will have positive impacts on plant populations and community interactions in fragmented landscapes. Corridors are thought to facilitate movement between connected patches of habitat, thus increasing gene flow, promoting reestablishment of locally extinct populations, and increasing species diversity within otherwise isolated areas (1-4). But the utility of corridors in conservation and management has generated extensive controversy because the case for corridors has been built more on intuition than on empirical evidence (5-7). Although recent studies suggest that corridors increase movement rates between patches for a broad range of animal species (2, 8-12), other studies show no such response (13-16). In large part, controversy has arisen because most studies have been limited in two ways. First, most corridor studies have had a narrow taxonomic focus on one to several species of animals. Such focus precludes generalizations and overlooks the fact that animals are only one component of biological communities. If corridors facilitate animal movement, they should also have strong indirect effects on plant populations due to increased movement of pollen and seeds by animals (17-20). These indirect effects are critically understudied (21), and there have been no studies linking the effects of corridors across these plant-animal interactions. Maintenance of these interactions is a growing concern, as efforts to preserve biodiversity move beyond their traditional focus on individual species (22-25). Second, most previous corridor studies have neglected the inherent difficulty of teasing apart effects due to corridor-facilitated movement from effects due to changes in patch size and shape that accompany the addition of a corridor (15). In particular, linking two patches of habitat with a corridor increases the area of those patches. If corridors function by increasing patch area, the population dynamics within a patch connected by a corridor should be identical to the dynamics of a patch that is increased in area by the size of the corridor (15, 26, 27). In this situation, management schemes solely oriented toward corridors would be misdirected. A further complication is that corridors affect patch shape in ways that may alter their function in unexpected ways. For example, they may act as drift-fences, intercepting individuals moving through matrix habitat and diverting them into connected patches (15). This function has not been separated from the traditional corridor effect (i.e., the facilitation of movement between connected patches). From a conservation perspective, these problems are not trivial. Should policies focus on increasing the area of reserves, regardless of connectivity, or does the addition of a corridor provide benefits to plants and animals above and beyond those afforded by increased area alone? Here we present results from an experiment designed to explicitly test corridor effects on animals and plant-animal interactions at a landscape scale, while experimentally controlling for changes in patch size and shape. | View Paper |
| Benefits and Consequences For Local Communities | Thapa, Kanchan & Wikramanayake, Eric & Malla, Sabita & Acharya, Krishna & Lamichhane, Babu & Subedi, Naresh & Pokheral, Chiranjibi & Thapa, Gokarna & Dhakal, Maheshwar & Bista, Ashish & Borah, Jimmy & Gupta, Mudit & Maurya, Kamlesh & G.s, Gurung & Jnawali, Shant & Pradhan, Narendra & Bhata, Shiv & Koirala, Saroj & Ghose, Dipankar & Vattakaven, Joseph. (2017). Tigers in the Terai: Strong evidence for meta-population dynamics contributing to tiger recovery and conservation in the Terai Arc Landscape. PLoS ONE. 12. 10.1371/journal.pone.0177548. | The source populations of tigers are mostly confined to protected areas, which are now becoming isolated. A landscape scale conservation strategy should strive to facilitate dispersal and survival of dispersing tigers by managing habitat corridors that enable tigers to traverse the matrix with minimal conflict. We present evidence for tiger dispersal along transboundary protected areas complexes in the Terai Arc Landscape, a priority tiger landscape in Nepal and India, by comparing camera trap data, and through population models applied to the long term camera trap data sets. The former showed that 11 individual tigers used the corridors that connected the transboundary protected areas. The estimated population growth rates using the minimum observed population size in two protected areas in Nepal, Bardia National Park and Suklaphanta National Park showed that the increases were higher than expected from growth rates due to in situ reproduction alone. These lines of evidence suggests that tigers are recolonizing Nepal’s protected areas from India, after a period of population decline, and that the tiger populations in the transboundary protected areas complexes may be maintained as meta-population. Our results demonstrate the importance of adopting a landscape-scale approach to tiger conservation, especially to improve population recovery and long term population persistence. | View Paper |
| Species Richness | Thiele, Jan & Kellner, Simon & Buchholz, Sascha & Schirmel, Jens. (2018). Connectivity or area: what drives plant species richness in habitat corridors?. Landscape Ecology. 33. 10.1007/s10980-017-0606-8. | The relative importance of habitat area and connectivity for species richness is often unknown. Connectivity effects may be confounded with area effects or they may be of minor importance as posited by the habitat-amount hypothesis. Objectives We studied effects of habitat area and connectivity of linear landscape elements for plant species richness at plot level. We hypothesized that connectivity of linear landscape elements, assessed by resistance distance, has a positive effect on species richness beyond the effect of area and, further, that the relative importance of connectivity varies among groups of species with different habitat preferences and dispersal syndromes. Methods We surveyed plant species richness in 50 plots (25 m2) located on open linear landscape elements (field margins, ditches) in eight study areas of 1 km2 in agricultural landscapes of Northwest Germany. We calculated the area of linear landscape elements and assessed their connectivity using resistance distance within circular buffers (500 m) around the plots. Effects of area and connectivity on species richness were modelled with generalised linear mixed models. ResultsSpecies richness did not increase with area. Resistance distance had significant negative effects on total richness and on the richness of typical species of grasslands and wetlands. Regarding dispersal syndromes, resistance distance had negative effects on the richness of species with short-distance, long-distance and aquatic dispersal. The significant effects of resistance distance indicated that species richness increased with connectivity of the network of linear landscape elements. Conclusions Connectivity is more important for plant species richness in linear landscape elements than area. In particular, the richness of plant species that are dispersal limited and confined to semi-natural habitats benefits from connective networks of linear landscape elements in agricultural landscapes. | View Paper |
| Species Movement and Dispersal, Influencing Animal Behavoir | Tigas, Lourraine & Vuren, Dirk & Sauvajot, Raymond. (2002). Behavioral responses of bobcats and coyotes to habitat fragmentation and corridors in an urban environment. Biological Conservation. 108. 299-306. 10.1016/S0006-3207(02)00120-9. | We examined the behavior of bobcats and coyotes in a fragmented urban area northwest of Los Angeles, California, from July 1998 to October 1999. Activity patterns of bobcats and coyotes were crepuscular with no apparent shift to nocturnality, but activity was somewhat lower during daylight hours than in an unfragmented reference area, implying some avoidance of humans. Home ranges were not significantly larger in fragmented than in unfragmented habitat, probably because unproductive development within a home range may have been balanced by availability of human-related food, such as fruit, garbage, and pets. Female bobcat home ranges were generally within a single fragment, while male bobcats and coyotes of both sexes included more than one fragment. Both species tended to cross over roads rather than use culverts. Culverts were more likely to be used earlier in the night, during heavier traffic, and if they contained less water. Bobcats and coyotes used corridors as habitat and, less often, for travel. Both species also crossed development to move between fragments, but seemed to prefer corridors when available. Our results indicate that bobcats and coyotes persisting in an urban environment adjust behaviorally to habitat fragmentation and human activities, in part through temporal and spatial avoidance. Both species appeared willing to cross well-travelled roads despite the availability of culverts; consequently, vehicular collision is an important cause of mortality (50%) and needs attention. | View Paper |
| Plant Dispersal | Tikka, P. M., HĦgmander, H., & Koski, P. S. (2001). Road and railway verges serve as dispersal corridors for grassland plants. Landscape Ecology, 16(7), 659-666. | The role of linear habitat strips as dispersal corridors is a disputed topic. Reports concerning their significance for animals have been contradictory, and the functions of corridors have been difficult to study in the case of sedentary organisms such as plants. Previous studies on dispersal of plants along corridors have concentrated on a single or a few species at a time. We developed a general method, a generalisation of the binomial test, for considering dispersal or spatial relations of a large group of species. Particularly, we studied the ability of grassland plants to spread along road and railway verges. Our data set consists of plant lists collected at study plots scattered irregularly along road and railway networks. The dispersal ability was assessed by testing whether the species composition at neighbouring sites measured along roads and railways reflects spatial dependence within each species. Our result showed that similar combinations of grassland species occurred at neighbouring sites more often than expected in a spatially independent case. We argue that management of verges and spatial autocorrelation of environmental factors were not responsible for the result and thereby we conclude that grassland plants use road and railway corridors for dispersal. This result is encouraging in regards to preservation of grassland plant populations. Although semi-natural and natural grasslands have become scarce, road and railway embankments may partly compensate for this loss, serving as substitute habitats and dispersal routes. | View Paper |
| Plant Dispersal | Townsend, 2005 AN EXPERIMENTAL TEST OF WHETHER HABITAT CORRIDORS AFFECT POLLEN TRANSFER. Ecology, Wiley Online Library. (n.d.). | Negative effects of habitat fragmentation are thought to be diminished when habitat patches are joined by a corridor. A key assumption is that corridors facilitate exchange rates of organisms between otherwise isolated patches. If the organisms are pollinators, corridors may be important for maintaining genetically viable populations of the plants that they pollinate. We tested the hypothesis that corridors increase the movement of insect pollinators into patches of habitat and thereby increase pollen transfer for two species of plants, one pollinated by butterflies (Lantana camara) and the other by bees and wasps (Rudbeckia hirta). We worked in an experimental landscape consisting of 40, 1-ha patches of early-successional habitat in a matrix of forest. Within each of eight experimental units, two patches were connected by a corridor (150x25 m), and three were not. Patch shape varied to control for the area added by the presence of a corridor. Differences in patch shape also allowed us to test alternative hypotheses of how corridors might function. The Traditional Corridor Hypothesis posits that corridors increase immigration and emigration by functioning as movement conduits between patches. The Drift Fence Hypothesis posits that corridors function by capturing organisms dispersing through the matrix, redirecting them into associated habitat patches. Using fluorescent powder to track pollen, we found that pollen transfer by butterflies between patches connected by a corridor was significantly higher than between unconnected patches (all values mean ‚± 1‚ se: 59% ‚± 9.2% vs. 25% ‚± 5.2% of flowers receiving pollen). Likewise, pollen transfer by bees and wasps was significantly higher between connected patches than between unconnected patches (30% ‚± 4.2% vs. 14.5% ‚± 2.2%). These results support the Traditional Corridor Hypothesis. There was little support, however, for the Drift Fence Hypothesis. To generalize our results to a larger scale, we measured the probability of pollen transfer by butterflies as a function of distance along a 2000x75 m corridor. Pollen transfer probability exponentially declined with respect to distance and successfully predicted pollen transfer probability on the scale of our previous experiment. These results suggest that corridors facilitate pollen transfer in fragmented landscapes. | View Paper |
| Species Movement and Dispersal, Benefits and Consequences For Local Communities | Tucker, Nigel & Simmons, Tania. (2009). Restoring a rainforest habitat linkage in north Queensland: Donaghy’s Corridor. Ecological Management & Restoration. 10. 98 - 112. 10.1111/j.1442-8903.2009.00471.x. | Donaghy’s Corridor is a 1.2 km × 100 m planting of rain forest species on the Atherton Tableland, Queensland, designed to link an isolated fragment (498 ha) to adjacent continuous forest (80 000 ha). Vegetation and fauna monitoring commenced immediately after the linkage was completed. Vegetation surveys showed 119 plant species established in the linkage in 3 years, and 35 of these were not known to occur within the extant linkage either as planted stock or as natural individuals existing prior to project commencement. There were differences between the fauna trapped within the restoration, adjacent open pasture habitats, forest interior sites and forest edge sites. Differences likely reflect variation in species habitat preferences and the habitat suitability of the planted vegetation. Now over 10 years old, Donaghy’s Corridor has developed a complex forest structure, with the tallest planted stems exceeding 20 m in height. This feature article provides information about the planning, implementation and monitoring of the linkage, and shows how restoring landscape and ecological connectivity can be a locally effective strategy to counter forest fragmentation. | View Paper |
| Species Richness | van der Ree, Rodney & Heinze, Dean & Mccarthy, Michael & Mansergh, Ian. (2009). Wildlife Tunnel Enhances Population Viability. Ecology and Society; Vol. 14, No. 2 (2009). 14. 10.5751/ES-02957-140207. | Roads and traffic are pervasive components of landscapes throughout the world: they cause wildlife mortality, disrupt animal movements, and increase the risk of extinction. Expensive engineering solutions, such as overpasses and tunnels, are increasingly being adopted to mitigate these effects. Although some species readily use such structures, their success in preventing population extinction remains unknown. Here, we use population viability modeling to assess the effectiveness of tunnels for the endangered Mountain Pygmy-possum (Burramys parvus) in Australia. The underpasses reduced, but did not completely remove, the negative effects of a road. The expected minimum population size of reconnected population remained 15% lower than that of a comparable undivided population. We propose that the extent to which the risk of extinction decreases should be adopted as a measure of effectiveness of mitigation measures and that the use of population modeling become routine in these evaluations. | View Paper |
| Species Movement and Dispersal | Van Wieren, S. E., & Worm, P. B. (2001). The use of a motorway wildlife overpass bylarge mammals. Netherlands Journal of Zoology , 51 (1), 97–105. | We studied how mammals used a wildlife overpass across a motorway in central Netherlands using track counts in 1989, 1994 and 1995. Throughout the study the overpass was used most frequently by red deer (Cervus elaphus) and wild boar (Sus scrofa) and, less often, by roe deer (Capreolus capreolucs), red fox (Vulpes vulpes), fallow deer (Duma duma), Highland cattle, and badger (Meles meles). For red deer and wild boar the highest incidence of use was in autumn/early winter, correlating with the rutting season. Small mammals caught on the overpass were wood mouse (Apodemus sylvaticus), common vole (Microtus arvalis) and common shrew (Sorex araneus). The wildlife overpasses can be an effective means of connecting habitats for a wide range of mammals but the effectiveness is related to the width of the overpass. For large mammals a minimum width of 40-50 meters is recommended. | View Paper |
| Species Richness | Vergnes, A., I. Le Viol, and P. Clergeau, Green corridors in urban landscapes affect the arthropod communities of domestic gardens. Biological conservation, 2012. 145(1): p. 171-178. | Ecological corridors are landscape elements that prevent the negative effects of fragmentation. However, their effectiveness has never been clearly validated in urban landscapes. We analysed the role of green corridors in an urban context by comparing metacommunities of arthropods in (i) woodlots considered as sources of species, (ii) woody corridors and domestic gardens that are (iii) connected (CG) or (iv) disconnected to corridors (DG) and taking into account the connectivity of the matrix. We trapped 3 taxa of arthropods - spiders, carabids and staphylinids -because they are sensitive to frost. For the 3 taxa, the taxonomic and functional compositions of communities in CG were closer to those of the corridor and the source than those of DG. Woodland species were associated with source, corridor and CG. A lower abundance in DG was revealed for staphylinids and spiders. Lower species richness in DG was observed for staphylinids.agmentation but with different dispersal capabilities. We analysed their species richness, abundance and taxonomic and functional composition. The differences between taxa could be explained by the dispersal capabilities of the species and by their various responses to landscape structures. For carabids, processes at a wider scale could be responsible for their rarity in sources and, consequently, in gardens. For spiders, the colonisation from other sources could explain the high species richness found in disconnected gardens. Our results suggest that the role of corridors is crucial for enhancing biodiversity in green spaces such as domestic gardens. Our results clarify the effectiveness of corridors in urban landscapes and have direct implications for the ecological | View Paper |
| Population Abundance | Vink, J. & Apeldoorn, & Bekker, G.J.. (2008). Defragmentation measures and the increase of a local European badger (Meles meles) population at Eindegooi, the Netherlands. Lutra 51 (2008) 2. | Twenty four years- data on European badger (Meles meles) and sett numbers have been collected by direct observation of a local population at Eindegooi, which straddles the Dutch provinces of Utrecht and NoordHolland. The population has shown periods of both slow and exponential growth and spatial dynamics show colonization of the entire study area. Analysis of how population dynamics respond to defragmentation measures involving roads has been undertaken. This suggests that tunnels and other measures make a positive contribution. At low densities and during periods of slow growth these measures can increase the lifetime of reproducing individuals and help badgers to safely disperse and colonize new habitat patches. Their positive effect on the population is illustrated by the fact that an individual's mortality risk from traffic has remained more or less constant, despite the increasing number of cars on motorways and provincial roads that dissect the study area. | View Paper |
| Species Movement and Dispersal | Vos, C. C., & Chardon, J. P. (1998). Effects of habitat fragmentation and road density on the distribution pattern of the moor frog Rana arvalis. Journal of applied Ecology, 35(1), 44-56. | 1.The effects of habitat fragmentation on the distribution pattern of the moor frog Rana arvalis were investigated. Also, the possible isolation effects of the road network were taken into account. 2.Indications were found that habitat fragmentation partly explains the distribution pattern of the moor frog. The statistical models showed a positive effect of pond size (or marsh area) and a negative effect of road density on the probability of occupation of a moorland pond. 3.Because of the strong correlation between habitat quality variables and isolation variables, no unambiguous effects of isolation, described as the amount of suitable terrestrial habitat (moorland) in the surroundings of a moorland pond in a radius of 100-2000 m, could be demonstrated. 4.Spatial differences in road density can play a role in the selection of optimal locations for nature protection areas. The regression model used in this study predicts a reduced occupation probability in 55% of the study area. In the part of the study area adjacent to a motorway, occupation probability is lowered to less than 30%. 5.European studies of habitat fragmentation on amphibian species revealed a mean distance between occupied ponds of <1 km in all studies. This could be a general rule of thumb for persistent amphibian populations. Effects of pond size on the probability of occupation were more variable. 6.When discussing the effects of habitat fragmentation on amphibians and other ground dwelling species, the negative effects of roads are often underestimated. | View Paper |
| Species Movement and Dispersal | Vos, Claire & Baveco, Hans & Grashof-Bokdam, Carla. (2002). Corridors and Species Dispersal. In: K.J. Gutzwiller (ed.), Applying landscape ecology in biological conservation. New York (USA) etc., Springer, 2002, pp. 84-104. 10.1007/978-1-4613-0059-5_6. | After introducing corridor concepts, we explore how those concepts have been applied and whether the applications were effective. Based on empirical data, simulation models, and on-the-ground applications, general principles for developing effective corridors will be presented. In the last two sections, major knowledge gaps and research approaches for filling them are discussed. | View Paper |
| Species Movement and Dispersal | Wang, Fang & McShea, William & Wang, Dajun & Li, Sheng & Zhao, Qing & Wang, Hao & Lu, Zhi. (2014). Evaluating Landscape Options for Corridor Restoration between Giant Panda Reserves. PloS one. 9. e105086. 10.1371/journal.pone.0105086. | The establishment of corridors can offset the negative effects of habitat fragmentation by connecting isolated habitat patches. However, the practical value of corridor planning is minimal if corridor identification is not based on reliable quantitative information about species-environment relationships. An example of this need for quantitative information is planning for giant panda conservation. Although the species has been the focus of intense conservation efforts for decades, most corridor projects remain hypothetical due to the lack of reliable quantitative researches at an appropriate spatial scale. In this paper, we evaluated a framework for giant panda forest corridor planning. We linked our field survey data with satellite imagery, and conducted species occupancy modelling to examine the habitat use of giant panda within the potential corridor area. We then conducted least-cost and circuit models to identify potential paths of dispersal across the landscape, and compared the predicted cost under current conditions and alternative conservation management options considered during corridor planning. We found that due to giant panda's association with areas of low elevation and flat terrain, human infrastructures in the same area have resulted in corridor fragmentation. We then identified areas with high potential to function as movement corridors, and our analysis of alternative conservation scenarios showed that both forest/bamboo restoration and automobile tunnel construction would significantly improve the effectiveness of corridor, while residence relocation would not significantly improve corridor effectiveness in comparison with the current condition. The framework has general value in any conservation activities that anticipate improving habitat connectivity in human modified landscapes. Specifically, our study suggested that, in this landscape, automobile tunnels are the best means to remove current barriers to giant panda movements caused by anthropogenic interferences | View Paper |
| Species Richness | Wang, Y., Guan, L., Piao, Z., Wang, Z., & Kong, Y. (2017). Monitoring wildlife crossing structures along highways in Changbai Mountain, China. Transportation Research Part D: Transport and Environment, 50, 119-128. | In China, the construction and monitoring of wildlife crossing structures is uncommon. Mountainous area occupies two-thirds area of China. A lot of tunnels (similar to overpasses in developed countries), bridges, and culverts (similar to underpasses) are constructed along highways. In general, these structures are multifunctional, including wildlife migration. However, studies on monitoring these potential crossing structures are almost vacant. Taking two highways in Changbai Mountain area as case studies, infra-red camera trapping and snow tracking were used to investigate the efficiency of tunnels, bridges and culverts on the highways. A total of 13 medium and large-sized wildlife species crossed highway through tunnels, bridges and culverts. One third of species were Chinese national protective species, and almost all species were present within 500 m from Ring Changbai Mountain Scenic highway used bridges and culverts to cross this highway. The tunnel along the expressway (length = 1000 m) and the bridges along the highway (width > 8 m) have been important passages for ungulates, Eurasian red squirrels (Sciurus vulgaris), yellow throated martens (Martes flavigula) and sables (Martes zibellina). Different species preferred to different types of structures, although most species preferred to bridges and tunnels. We suggest that short fences should be set around the bridges and culverts to guide animals to cross the passages, especially for ungulates. Monitoring programs of uses of crossing structures by wildlife should be conducted for at least 2 months to catch most species activity. | View Paper |
| Species Movement and Dispersal | Weeks, S.. (2015). Case Study: The Mount Kenya Elephant Corridor and Underpass. 10.1002/9781118568170.ch43. | Mount Kenya is Africa's second highest peak and is an important source of water for agriculture and hydro?electricity. Historically, elephants moved between Mount Kenya and the Ngare Ndare Forest and the lower drier country to the north. The choice to construct an underpass was confirmed when elephants were observed using a culvert in KwaZulu?Natal, South Africa. The underpass was opened in December 2010 and it was used by an elephant (now known as Tony) on the first night. The Marania and Kisima Farms that donated land for the elephant corridor have also been included within the World Heritage Site, and elephant damage is now minimal. The elephant corridor crosses a dirt road and elephants are discouraged from leaving the corridor via the road by electrified wires suspended above the road. The Mount Kenya Trust and partners are currently raising funds to build a similar underpass under this rural road. | View Paper |
| Benefits and Consequences For Local Communities | Wegge et. al.. 2018. Are corridors good for tigers Panthera tigris but bad for people? An assessment of the Khata corridor in lowland Nepal. | As part of a landscape-scale programme for conserving tigers Panthera tigris the Khata corridor was established between Bardia National Park in Nepal and Katarniaghat Wildlife Sanctuary in India in early 2000. We examined its functionality by comparing the status of tigers and prey in the corridor and in the adjacent National Park, using camera trapping, transect sampling and diet analysis of scats. Tiger movement was inferred from the photographs, and tiger–human conflict was assessed by means of questionnaires and interviews. The corridor harboured transient individuals as well as resident, breeding tigers. Tigers with core areas in the corridor were also recorded in the two protected areas, and vice versa. Wild prey was 3–4 times more abundant in the area of the National Park bordering the corridor than in the corridor itself, and domestic livestock constituted 12–15% of the tigers’ food in the corridor. Livestock losses and human fatalities or injuries were relatively low compared to within the buffer zones of the National Parks. Despite such problems and restrictions on grazing and extraction of natural resources, local residents were generally positive towards tigers and the corridor. The successful establishment of the corridor and the positive attitudes of local people were attributable to community development programmes initiated to compensate for the imposed restrictions, financed by the government and national and international organizations. By linking Bardia National Park and Katarniaghat Wildlife Sanctuary via the Khata corridor, a protected tiger landscape of c. 3,000 km ² was established in west-central Nepal and northern India. | View Paper |
| Benefits and Consequences For Local Communities | Wegge, Per, Shailendra Kumar Yadav, and Babu Ram Lamichhane. Are Corridors Good for Tigers Panthera Tigris but Bad for People? An Assessment of the Khata Corridor in Lowland Nepal. Oryx 52, no. 1 (January 2018): 35-45 | As part of a landscape-scale programme for conserving tigers (Panthera tigris) the Khata corridor was established between Bardia National Park in Nepal and Katarniaghat Wildlife Sanctuary in India in early 2000. We examined its functionality by comparing the status of tigers and prey in the corridor and in the adjacent National Park, using camera trapping, transect sampling and diet analysis of scats. Tiger movement was inferred from the photographs, and tiger-human conflict was assessed by means of questionnaires and interviews. The corridor harboured transient individuals as well as resident, breeding tigers. Tigers with core areas in the corridor were also recorded in the two protected areas, and vice versa. Wild prey was 3-4 times more abundant in the area of the National Park bordering the corridor than in the corridor itself, and domestic livestock constituted 12-15% of the tigers' food in the corridor. Livestock losses and human fatalities or injuries were relatively low compared to within the buffer zones of the National Parks. Despite such problems and restrictions on grazing and extraction of natural resources, local residents were generally positive towards tigers and the corridor. The successful establishment of the corridor and the positive attitudes of local people were attributable to community development programmes initiated to compensate for the imposed restrictions, financed by the government and national and international organizations. By linking Bardia National Park and Katarniaghat Wildlife Sanctuary via the Khata corridor, a protected tiger landscape of c. 3,000 km2 was established in west-central Nepal and northern India. | View Paper |
| Population Abundance | Weldon, A. J. (2006). How corridors reduce Indigo Bunting nest success. Conservation Biology, 20(4), 1300-1305. | Corridors are a popular strategy to conserve biodiversity and promote gene flow in fragmented landscapes. Corridor effectiveness has been bolstered by the fact that no empirical field studies have shown negative effects on populations or communities. I tested the hypothesis that corridors increase nest predation in connected habitat fragments relative to unconnected fragments. I evaluated this hypothesis in a large-scale experimental system of open-habitat fragments that varied in shape and connectivity. Corridors increased nest predation rates in connected fragments relative to unconnected fragments with lower edge:area ratios. Nest predation rates were similar between connected and unconnected fragments with higher edge:area ratios. These results suggest that the increase in predator activity is largely attributable to edge effects incurred through the addition of a corridor. This is the first field study to demonstrate that corridors can negatively impact animal populations occupying connected fragments. | View Paper |
| Genetic Variation | Wells, Carrie & Williams, Ray & Walker, Gary & Haddad, Nick. (2009). Effects of Corridors on Genetics of a Butterfly in a Landscape Experiment. Southeastern Naturalist - SOUTHEAST NAT. 8. 709-722. 10.1656/058.008.0412. | To investigate the possible role of landscape connectivity on the genetic structure of isolated populations, we examined the effects of habitat corridors on the population genetics of a vagile butterfly species, Junonia coenia, within a large-scale, experimental system. Using allozyme electrophoresis, a total of nine loci were identified and scored, six of which exhibited polymorphism. Our data demonstrated consistently higher levels of expected (He) and observed (Ho) heterozygosity in butterflies sampled from patches connected by corridors compared to unconnected patches. A t-test comparing He and H0 in connected versus unconnected patches found a marginally significant difference in one locus, the glycolytic enzyme phosphoglucose isomerase (PGI). Connected patches exhibited overall lower FST values compared to unconnected patches, indicating potentially increased levels of gene flow due to corridors. Our results support previous investigations on dispersal and population size for J. coenia, and show that higher dispersal through corridors promotes genetic variability at a locus (PGI) implicated in dispersal and fitness in butterflies. | View Paper |
| Benefits and Consequences For Local Communities | Weston, N., Goosem, M., Marsh, H., Cohen, M., & Wilson, R. 2011. Using canopy bridges to link habitat for arboreal mammals: successful trials in the Wet Tropics of Queensland. Australian Mammalogy, 33(1), 93. | View Paper | |
| Benefits and Consequences For Local Communities | Wikramanayake, Eric & Manandhar, Anil & Bajimaya, Shyam & Nepal, Santosh & Thapa, Gokarna & Thapa, Kanchan. (2010). The Terai Arc Landscape: A Tiger Conservation Success Story in a Human-dominated Landscape. Tigers of the World. 163-173. 10.1016/B978-0-8155-1570-8.00010-4. | The Terai is one of the most fragmented and threatened ecosystems in Asia. The large mammals of the Terai are mostly confined to the protected areas, although the ecological and behavioral traits of these species demand extensive habitat areas for effective, long-term conservation. The conservation challenge in the Terai is to manage and maintain ecologically, demographically, and genetically viable populations of the Terai's endangered mega species. To achieve this goal, a coalition of governmental and non-governmental partners from Nepal and India adopted a landscape-scale conservation strategy to connect twelve protected areas across the Himalayan foothills with habitat linkages to facilitate species dispersal and seasonal movements. Since the tiger is an important focal species in the Terai, the linkages are identified based on its ecological requirements and behavioral characteristics. This chapter reveals that a strategy that elicits local stewardship to link core refuges for conservation of tigers and other iconic Mega species of Asia, which are losing ground against the human tide, is possible even in human-dominated landscapes. Humans and wildlife have co-existed for millennia in Asia, and people who have traditionally lived with wildlife in their backyards are usually tolerant to some degree of depredation and crop damage. Therefore, if conflict can be maintained at low levels, and both people and wildlife can share the benefits of conservation, there can be scope for their co-existence. | View Paper |
| Species Movement and Dispersal | Wikramanayake, Eric & Manandhar, Anil & Bajimaya, Shyam & Nepal, Santosh & Thapa, Gokarna & Thapa, Kanchan. (2010). The Terai Arc Landscape: A Tiger Conservation Success Story in a Human-dominated Landscape. Tigers of the World. 163-173. 10.1016/B978-0-8155-1570-8.00010-4. | The Terai is one of the most fragmented and threatened ecosystems in Asia. The large mammals of the Terai are mostly confined to the protected areas, although the ecological and behavioral traits of these species demand extensive habitat areas for effective, long-term conservation. The conservation challenge in the Terai is to manage and maintain ecologically, demographically, and genetically viable populations of the Terai's endangered mega-species. To achieve this goal, a coalition of governmental and non-governmental partners from Nepal and India adopted a landscape-scale conservation strategy to connect twelve protected areas across the Himalayan foothills with habitat linkages to facilitate species dispersal and seasonal movements. Since the tiger is an important focal species in the Terai, the linkages are identified based on its ecological requirements and behavioral characteristics. This chapter reveals that a strategy that elicits local stewardship to link core refuges for conservation of tigers and other iconic megaspecies of Asia, which are losing ground against the human tide, is possible even in human-dominated landscapes. Humans and wildlife have co-existed for millennia in Asia, and people who have traditionally lived with wildlife in their backyards are usually tolerant to some degree of depredation and crop damage. Therefore, if conflict can be maintained at low levels, and both people and wildlife can share the benefits of conservation, there can be scope for their co-existence. | View Paper |
| Invasive Species | Wilcove, D. S., Rothstein, D., Dubow, J., Phillips, A., & Losos, E. (1998). Quantifying Threats to Imperiled Species in the United States. BioScience, 48(8), 607-615. doi: 10.2307/1313420 | Biologists are nearly unanimous in their belief that humanity is in the process of extirpating a significant portion of the earth's species. The ways in which we are doing so reflect the magnitude and scale of human enterprise. Everything from highway construction to cattle ranching to leaky bait buckets has been implicated in the demise or endangerment of particular species. According to Wilson (1992), most of these activities fall into four major categories, which he terms "the mindless horsemen of the environmental apocalypse": overexploitation, habitat destruction, the introduction of non-native (alien) species, and the spread of diseases carried by alien species. To these categories may be added a fifth, pollution, although it can also be considered a form of habitat destruction. | View Paper |
| Population Abundance | Williams, J. R., Driscoll, D. A., & Bull, C. M. (2012). Roadside connectivity does not increase reptile abundance or richness in a fragmented mallee landscape. Austral ecology, 37(3), 383-391. | The effect of isolation and the importance of dispersal in establishing and maintaining populations in fragments of remnant habitat remain poorly understood. Nevertheless, environmental connectivity is likely to be important for ensuring the long-term preservation of biodiversity in extensively cleared landscapes. In this study, we compared reptile communities in large conservation parks with those in small woodland remnants 6.5-12-km from the parks, on the Eyre Peninsula, South Australia, Australia. We assessed the impact of fragmentation on the abundance, richness and habitat preferences of reptiles, and examined whether connection to linear roadside vegetation altered reptile communities in small woodland remnants. Of the 31 reptile species, 12 were restricted to conservation parks and six to habitat fragments in farmland. There was a substantial reduction in reptile species richness and abundance in farmland fragments. Direct connection of remnant vegetation to roadside corridors did not affect abundance of common species in the farmland fragments, although species richness was lower in isolated remnants in one of our two study regions. The habitat preference of the scincid lizard‚ Menetia greyii‚ differed between farmland fragments, where they were regularly found on dunes and roadsides, and conservation parks, where they were rare and not detected on dunes. We suggest that habitat fragmentation may have altered interspecific interactions, enabling an expansion of habitat use in the farming landscape. Significantly lower abundance of four common species in farmland settings compared with reserves indicated that existing corridors and small fragments provide inadequate connectivity over larger distances. To counter this effect, large reserves may need to be less than 10-km apart. | View Paper |
| Influencing Animal Behavior | Wilson, E. O., & Willis, E. O. (1975). Applied biogeography Pp. 522-534 in Ecology and evolution of communities (Cody, M. L. & Diamond, J. M., eds). Harvard University Press, Cambridge, Massachusetts. | n/a | |
| Species Movement and Dispersal, Population Abundance | Woess, M. & Grillmayer, Roland & Voelk, F.. (2002). Green bridges and Wildlife Corridors in Austria. Zeitschrift f ur Jagdwissenschaft. 48. 25-32. 10.1007/BF02192389. | Landscapes and landscape structures that enable migrations, spreading and the exchange of large animal species between subpopulations are becoming increasingly scarce resources in densely populated Europe. Two projects in Austria provide the necessary foundations for the management of these resources. In the project. Reducing the cost of green bridges through their rational use, the permeability of the higher-level and fenced road network necessary for adequate networking was demonstrated. The permeability actually found was determined by evaluating all existing overpasses and underpasses with a width of more than 30 m (from the point of view of the game) with regard to their suitability for wild animals and by surveying the most important game corridors for deer, Moose and predators using map analysis, surveys and evaluation of existing data. A comparison of the necessary and the actual permeability finally resulted in a green bridge concept for the Austrian expressway and motorway network. In the "Wild Ecological Corridors" project, remote sensing options for the detection of corridor structures were tested and applied on the basis of a partial area of the Alpine-Carpathian Corridor. Using the data and information obtained from the terrestrial surveys, aerial and satellite image analyzes, it was possible to Permeability model, valid for red and wild boar, to be developed for the study area. The most likely migration route between the Danube and the Leithauen could be determined. | View Paper |
| Genetic Variation | Wood, Darren & Welsh, A. & Petty, Todd. (2018). Genetic Assignment of Brook Trout Reveals Rapid Success of Culvert Restoration in Headwater Streams. North American Journal of Fisheries Management. 38. 10.1002/nafm.10185. | Fragmentation of aquatic habitats is a global conservation concern. Losses of both biodiversity and genetic diversity have been attributed to this phenomenon as dispersal movements between habitat patches are restricted. Brook Trout Salvelinus fontinalis in the upper Shavers Fork watershed of West Virginia exhibit high dispersal rates and lengthy dispersal distances; however, road culverts have been hypothesized to influence the movement of Brook Trout between tributaries. Removing impassable culverts could serve as a tool to facilitate movements into previously isolated streams. We classified the passability of road culverts by their physical attributes and collected samples above each structure as well as in two streams without culverts to test for genetic population differentiation attributed to culverts. After we determined that the majority of streams consisted of a single genetic population, with the exception of two streams containing culverts designated as impassable (Beaver Creek and Lamothe Hollow), the culvert structures were restored to eliminate outlets perched above the stream bottom and were subsequently resampled 1 year after project completion. Although no individuals were assigned as first generation migrants into either Beaver Creek or Lamothe Hollow before culvert restoration, five individuals were detected as first generation migrants into Beaver Creek (13%), and one individual was identified as a first generation migrant into Lamothe Hollow (4.5%) after culvert restoration. Three different streams were found to be sources of the migrants into Beaver Creek, and the single individual migrating into Lamothe Hollow was from a fourth source stream. The identification of first generation migrants through genetic assignment not only provides a tool with which to test the effectiveness of barrier removal and subsequent restoration success but also to support the importance of culvert replacement in headwater streams. | View Paper |
| Species Movement and Dispersal | WRIGHT, S. (1950). Wright S.. The Genetical Structure of Populations. Ann Eugenic 15: 323-354. Nature. 166. 247-9. 10.1111/j.1469-1809.1949.tb02451.x. | View Paper | |
| Species Movement and Dispersal | Wu, W. & Feng, J. & Ou, M.. (2018). Habitat network optimization using landscape functional connectivity: A case study of the little egret (Egretta garzetta) in the Su-Xi-Chang area, China. Shengtai Xuebao/ Acta Ecologica Sinica. 38. 8336-8344. 10.5846/stxb201708051407. | Habitat networks have a vital function in inhibiting habitat fragmentation and in enhancing biodiversity conservation due to connectivity among habitat patches. However,in previous studies, habitat network optimization has focused mainly on landscape structural connectivity rather than on functional connectivity, but the latter has more ecological significance. Therefore, the objectives of this study were to optimize habitat networks by combining the graphic and the probability of moving between patches theoretical methods for landscape functional connectivity and to attempt to answer the following research questions:( 1) What characteristics are exhibited by habitat networks that are optimized through functional connectivity?( 2) What advantages do the optimized networks have in reserve plan and land-use plan implementation? Using this approach, an ideal threshold and an acceptable threshold were calculated and applied to classify current corridors,respectively,as well as newly added patches and corresponding corridors, which have significant landscape functional connectivity. The Su-Xi-Chang area, at the center of the Yangtze River Delta region of China and representing rapid urbanization, was selected for the study. The little egret( Egretta garzetta) was chosen as a regionally representative species, which is commonly recommended by animal ecologists. The results showed( 1) that the optimized habitat networks possess a higher density and clearer aggregation centers, whereas the optimized arterial networks have a high fitness with the long-distance migration direction of the little egret, which has already been proved and is commonly accepted, and(2) that optimized habitat and arterial networks comprising patches and corridors with significant features of landscape functional connectivity were both ideal results of the current habitat network optimization. This conclusion was verified by the network connectivity indices alpha( ?),beta( ?),and gamma( ?). Optimized arterial networks were recommended due to similar values of network connectivity indices and fewer habitat nodes and migration corridors than those of optimized habitat networks. Optimized arterial networks can be adopted as the minimum boundary of optimized habitat networks of the study area, especially in rapidly urbanizing areas, which provides a new idea suitable for regional biodiversity conservation. Furthermore, both current and newly added habitats and corridors were identified based on the land-use type classification issued by the Ministry of Land Resource Management of China, which can be easily adopted into local land-use planning and highly operatively implemented by land resource management. The developed approach of this study highlights habitat network rebuilding and development research, integrates a biodiversity conservation plan into local land-use planning, and increases the efficiency of both biodiversity conservation and land resource management. | View Paper |
| Ecosystem Services | Yin, Kaipu & Xie, Yan & Wu, Ning. (2006). Corridor connecting giant panda habitats from north to south in the Min Mountains, Sichuan, China. Integrative zoology. 1. 170-8. 10.1111/j.1749-4877.2006.00032.x. | The giant panda faces severe threats from habitat fragmentation and isolation. Currently, giant panda populations have been fragmented into 30 habitat patches. The disappearance of isolated small populations and studies on the genetic diversity of various populations have shown that small isolated panda populations are at a high risk of dying out completely. Habitat fragmentation has seriously impaired the ability of the giant panda to resist climate changes and other natural disasters, such as large scale, synchronous bamboo blooming. The Min Mountains have the largest population of pandas in China, numbering 581 individuals and accounting for 52% of the total (1114) in China. Geographic isolation means that giant pandas in the Min Mountains are divided into two populations (population A in the north and population B in the south). Population B, which had only 42 individuals in 1989, is severely threatened by high density human populations and the loss of genetic diversity. However, we have identified an important corridor connecting the two populations. This paper explains the importance and the feasibility of reestablishing this corridor. Due to the special geographic locations of these two populations (two rivers block the migration of giant pandas between south and north), the corridor is the only passage for giant pandas in the region. Recent studies have also shown an increase of giant panda activity in the area of the corridor. However, vegetation in the corridor has been severely degraded. Bamboo forest must be restored in this area to provide food for the pandas during migration. The effects of human activities must be reduced in order to maintain panda habitat. We believe that a restored corridor will be of great benefit to the survival of giant pandas in the Min Mountains, especially for population B. Successful re-establishment of a corridor will be a valuable model for corridor construction in the future. | View Paper |
| Ecosystem Services, Population Abundance, Benefits and Consequences For Local Communities, Species Richness? | Zhang, Zhenzhen & Meerow, Sara & Newell, Joshua & Lindquist, Mark. (2018). Enhancing Landscape Connectivity through Multi-functional Green Infrastructure Corridor Modeling and Design. Urban Forestry & Urban Greening. 38. 10.1016/j.ufug.2018.10.014. | Landscape connectivity is critical for ecosystem health and biodiversity conservation, yet urbanization is increasing habitat fragmentation. Green corridors that connect isolated remnant habitat patches (e.g. parks) can increase connectivity and provide ecosystem services in cities. Vacant land, especially prevalent in shrinking cities, presents a unique opportunity to reconnect these landscapes. This paper provides a practical and replicable approach for assessing landscape connectivity patterns and identifying priority locations for green corridors. The methodology integrates social and ecological factors coupled with site-scale multifunctional greenway designs and is applied to the city of Detroit as a proof of concept. First, we use FRAGSTATS to evaluate structural landscape connectivity patterns at a census tract scale. A functional connectivity assessment based on graph theory and Conefor software is used to validate the results, which indicate that habitat is highly fragmented in Detroit. To identify opportunities to reduce this fragmentation, we use a least-cost path approach to map potential green corridors linking city parks through vacant parcels, alleys, and smaller green spaces, and prioritize these corridors using a gravity model and network analysis. To make the model more concrete and useful for decision-makers, we develop site-level multifunctional corridor design typologies. This study presents a novel approach to assessing urban connectivity and a multi-scalar, systematic methodology for planning urban green infrastructure networks that connects landscape ecology with practical planning and design considerations to maximize social and ecological functions. | View Paper |
| Species Richness | Zimbres, B., C. Peres, and R. Machado, Terrestrial mammal responses to habitat structure and quality of remnant riparian forests in an Amazonian cattle-ranching landscape. Biological Conservation, 2017. 206: p. 283-292. | Riparian habitats are important for the maintenance of regional biodiversity. Many studies have compared bird distributions between riparian and non-riparian habitats but have not established how wide riparian habitats used by birds are, as measured by distance from the nearest stream. We investigated the distribution of understory birds along gradients of distance from streams, soil clay content, and slope in a central Amazonian forest, by mist-netting birds three times in 45 plots. We used nonmetric multidimensional scaling (NMDS) to reduce the dimensionality of species quantitative (abundance) and qualitative (presence-absence) composition to one multivariate axis. Estimates of the width of riparian habitats as indicated by understory birds depended on the community attribute considered, measuring 90 m for species quantitative composition and 140 m for species qualitative composition. Species distributions were correlated with clay content but were independent of slope, while distance from streams was positively correlated with clay content but independent of slope. Clay content affects plant species composition, which in turn, may influence bird species composition. However, distribution patterns of birds in relation to distance from streams are consistent among studies carried out in many different temperate and tropical regions, indicating an effect of distance from streams itself. Protection of riparian habitats is one of the most widely used conservation strategies, and Brazilian environmental legislation mandates the protection of a 30 m wide strip of riparian vegetation on either side of small streams. We show that the protected strip should be much wider and recommend strategies to place other forms of land protection contiguous with riparian areas so that Brazilian environmental legislation better fulfills its role of protecting biodiversity associated with riparian habitats. | View Paper |
| Plant Dispersal | Zink, Thomas & Allen, Michael & Heindl-Tenhunen, Bärbel & Allen, Edith. (2006). The Effect of a Disturbance Corridor on an Ecological Reserve. Restoration Ecology. 3. 304 - 310. 10.1111/j.1526-100X.1995.tb00098.x. | The effect of a pipeline corridor constructed through an ecological reserve in Southern California was investigated by assessing plant species composition and soil chemistry. A homogeneous plant community comprised primarily of exotic annuals was found along the entire length of the corridor. This community has low similarity to the adjacent native plant communities. Soil organic matter was significantly less on the disturbed corridor than in contiguous undisturbed areas. Both available nitrogen and extractable phosphorus values were greater in the disturbed corridor. By contrast, total nitrogen was significantly higher outside the pipeline. The more labile litter of the exotic annuals allows increased mineralization along the corridor than does the more recalcitrant litter of the native perennial shrubs in the undisturbed areas. Once established, the weedy exotic annual litter may completely turn over organic matter and nitrogen, favoring the persistence of the weedy annuals. These exotic annuals appear to be moving into three of the native communities ? grassland, coastal sage, and oak woodland ? that have less organic matter and a more open plant canopy. Poor restoration efforts can lead to the establishment of such exotics, subsequent invasion into the surrounding undisturbed habitat, and degradation of the reserve. | View Paper |