Category: Science Corner

The Health of Our Oceans: Seabirds as Sentinels.

September 16, 2019 erinwilligan

September 16, 2019

The Bird Catchers

A FILM BY JAMES ROBINSON

Sooty terns have been returning to the Dry Tortugas National Park in the Florida Keys to breed from mid-January through July for untold years. Scientists have been there to meet them since the 1930’s. An ambitious research project has collected decades of data on over 500,000 birds to help reveal the secrets of their life at sea.

Scientists can learn a lot from the terns about climate change and the health of our oceans. Because of the extensive area covered on their ocean journeys, terns are yielding new insights about how humans are altering the planet. Unfortunately, most of the insights come from mortalities of the terns.

But first, they have to catch them.

We recently got a unique perspective on what it takes to monitor the 500,000 sooty terns that have been banded over the life of the project. Created by James Robinson, a student at Duke University, we see the project through the eyes of young scientists following in the footsteps of Dr. Pimm to collect the data needed to understand our planet through the journey of the terns.

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In the eight decades since research began, sooty tern populations on the Dry Tortugas have dropped 84 percent, from 3 million birds to around 350,000. Their struggles could point to troubling changes in our oceans and our climate. Rising sea levels are flooding nesting grounds. More frequent and intense storms are battering terns in the open ocean. Over-fishing is depleting their food supply.

What We’ve Learned About Hurricanes

Dr. Ryan Huang, a scientist from Duke University led a recent study on the connection between hurricanes and seabird deaths. A new map produced by the research shows that sooty terns leave their breeding colony at Dry Tortugas National Park in the Florida Keys each June as hurricane season starts. They migrate southward and eastward across the Caribbean through summer and early fall, before skirting the northern coast of South America and arriving at their winter habitat off the Atlantic coast of Brazil in November.

Huang and his colleagues charted the migratory path by recording and mapping the dates and locations of all sooty terns banded for study at the Dry Tortugas since the 1950’s but found dead elsewhere. They also mapped locational data retrieved from birds that were fitted with satellite-telemetry tracking tags. When they overlaid all this data with maps of hurricane paths from the same period, they discovered a striking correlation between bird deaths and hurricanes.

Migration itself is a very stressful, very taxing process for these birds to undergo,” said Huang. “Encountering a storm adds even more stress, forcing the birds to fight strong winds and rain. Those that can’t handle that will likely die.” Unlike many shorebirds, sooty terns do not have special feather oils to help repel water, so they’re susceptible to drowning.

What We’ve Learned About Overfishing

In another recent study, tern feathers provided insights into the effects of overfishing. The feathers gave the scientists a window into broad changes in the terns’ diets over time. Starting at the end of the last century, presumably due to overfishing, the terns started eating more squid and small crustaceans, and fewer fish.

The change in diet corresponded with a decline in the sooty tern population. Fish are loaded with protein and fats and as such are a nourishing food source for seabirds and their fast-growing chicks; squid and crustaceans are not a good alternative.

Please support conservation efforts that fight climate change. For the terns. For all of us.

Categories: Research, Saving Nature Collection, Science Corner

How Can I Teach High School Students the Carbon Cycle?

September 15, 2018 Stuart Pimm

September 14, 2018

Stuart Pimm

Teaching children about the carbon cycle doesn’t have to be confusing. Once they understand the relationship between trees and climate change, they can be climate change ambassadors to friends and family. Here’s an exercise that Saving Nature’s President Stuart Pimm does with high school students.

HOW CAN I TEACH MY HIGH SCHOOL STUDENT THE CARBON CYCLE?

Because it’s a science class, Pimm starts with two key facts. He’ll be talking about tons of carbon — and burning one ton of carbon produces 3.7 tons of carbon dioxide. Second, he’ll be using the metric system.

How much does a tree weigh?

No one answers.

“Imagine a tree as a cylinder. The volume of a cylinder is its area — that’s pi r squared” — the class groans — “times its length” — more groans. But that’s the hard part.

Quickly, students estimate that a good-sized tree in the forests of eastern North America has a diameter of about one metre (so about three feet) and maybe ten metres (about thirty feet) tall. The volume comes to 7.85 cubic metres.

How heavy is wood is easy!” Pimm tells them.

Pimm reminds them of Archimedes and bath tubs.

“Put a stick in water, keep it upright, and notice that about 70% of it is underwater. That’s the specific gravity of wood.”

A cubic metre of water weighs a ton, so the tree weighs about 70% of that, and 70% of 7.85 is 5.5 tons.

How much of wood is carbon?

“Well weigh a piece, dry it, then burn it: the carbon has burned off as carbon dioxide.”

The answer is that wood is about half carbon — and so that one tree is 2.75 tons of carbon.

The class goes outside and measures how many trees of different sizes there are in an area of forest. Trees are not perfect cylinders, of course, but this simple exercise teaches some basic algebra and physics — which high school teachers love, even as their students groan. It also gets the students excited about how to improve the estimates, including how to estimate the height of a tree. (Simple algebra too, using the tool on the iPhone that estimates angles.)

Scaling up one tree to estimate carbon emissions from deforestation

The class comes back inside. There are good data online that show how much forests shrink each year. Look at satellite images on Google Earth that show that many forests are being cleared by burning them.

In an afternoon’s class, one can get sensible, if rough, estimates of the planet’s most important land-use change and of how much it contributes to the increase in the carbon dioxide in the atmosphere.

Certainly, these exercises make other important points. To do them correctly, one needs to spend a lot of effort in a lot of places to estimate the full range of values expected and how they vary across Earth’s different ecosystems. (The methods suggested here wouldn’t work well outside of Phoenix, Arizona, for example.)

When one has those values, then scientists can work out how best to predict them — from data obtained from satellite imagery, for example. Green places in the Eastern USA have more carbon than the desert southwest. But no satellite can save the hot, steamy, hard work of measuring trees! That’s fundamental

Putting Knowledge into Action

At Saving Nature, our work to reforest areas high in biodiversity solves two most pressing environmental problems the world faces—mass species extinction and global warming—at the same time!

We invite you to join us in this ambitious effort! Donating to Saving Nature puts trees in the ground for biodiversity, and sequesters carbon from the atmosphere.

Categories: Climate Change, Saving Nature Collection, Science Corner

Protecting 20% of Land to Save Two-Thirds of Plant Species

September 5, 2013 erinwilligan

September 5, 2013

You’ve heard the adage, “If it sounds too good to be true, it probably is.” But new research by Saving Nature scientists offers an amazing conservation ‘deal’. Backed up by top-flight science and data, it’s too good to pass up. So what is the deal? The new paper, published today in Science, was co-authored by Saving Nature founder Stuart Pimm and Vice President Clinton Jenkins, and by Lucas Joppa of Microsoft Research, who completed his Ph.D. with Pimm.

PROTECTING A FIFTH OF THE WORLD'S LAND TO SAVE TWO-THIRDS OF ALL PLANT SPECIES

The key finding of the paper is that protecting a fifth of the world’s land area will save two-thirds of the world’s endemic plant species. Using the Kew Gardens plant database, the authors looked at the geographical distributions of 110,000 plant species. From this analysis, the researchers identified the smallest set of regions that contain the largest number of plant species.

They discovered that nearly two-thirds of the world’s plants occur in just 17 percent of the world’s land. The bad news is that less than a sixth of that 17 percent is currently protected. “Our study identifies regions of importance. The logical – and very challenging – next step will be to make tactical local decisions within those regions to secure the most critical land for conservation.” Pimm said.

Incorporating years of data, Jenkins created a detailed, color-coded map of Earth. The map illustrates where endemic plants are concentrated. This information helps conservation ecologists, policy makers, and economists to prioritize locations for conservation eorts. Because of ecological food webs, protecting endemic plants not only helps save rare plant species—it helps save dependent species, such as specialist herbivores, epiphytes and so on. “We also mapped small-ranged birds, mammals and amphibians, and found that they are broadly in the same places we show to be priorities for plants,” said Jenkins. “So preserving these lands for plants will benefit many animals, too,” he said.

According to Pimm, to achieve biodiversity conservation goals, the world needs to protect more land than we currently do and much more in key places such as Madagascar, Colombia, and coastal Brazil. These are all places where Saving Nature works.

Saving Nature relies on cutting-edge science to make its conservation decisions. With the limited amount of conservation funding available, we must use the best science to maximize the number of threatened species of wildlife and plants we can save. The report’s findings truly oer conservationists a great deal.

SCIENTIFIC NOTE: The work in Science focused on endemic species of plants. Endemic species exist only in specific places, such as a particular mountain range or forest. Endemic species are typically very rare, because of their limited geographical distribution. Endemic plants are also crucial to ecosystems that support other endangered species and, more broadly, biodiversity. Because they exist only in one place, endemic plants are often hosts for other endemic species that depend on them—insects, animals, and even other plants such as epiphytes.

Categories: Brazil, Colombia, Ecuador, India, Research, Saving Nature Collection, Science, Science Corner, Sumatra