Judging Corridors Meant to Shuttle Wildlife

Wildlife biologists seek to determine whether wildlife corridors really work to connect fragmented pieces of habitat. The researchers collect bird droppings, which can tell them not only how the birds use corridors to move among wildlife reserves, but also where plant seeds in those droppings are likely to be carried.

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Farmers, loggers and builders have been slicing and dicing America's natural landscapes for hundreds of years. Once vast forests and wetlands have been cut into disconnected fragments, and rare plants and animals trapped inside these fragments often go extinct. Ecologists have tried to make it easier for animals to move between fragments by building natural corridors, but they haven't been able to tell if they work. Well, a new report in the journal Science suggests that they might based on a study of glow-in-the-dark bird droppings. Here's NPR's John Nielsen.

JOHN NIELSEN reporting:

Five years ago ecologist Doug Levey of the University of Florida got a call from a group of befuddled land use experts. They'd been looking through satellite photographs that showed landscapes cut into pieces and one of the pictures just didn't make sense.

Mr. DOUG LEVEY (University of Florida): This one damn site in South Carolina that had these really bizarre patches, very regularly shaped but not all exactly the same, that appeared out of nowhere.

NIELSEN: The site was an 800-acre pine forest with a great big treeless circle in the middle of it. Five smaller treeless circles ringed the big one each several hundred yards away. One of the small circles was connected to the big one in the middle by a narrow corridor of brush. No, it is not a crop circle, Levey told the experts. It is his research site, the one he had designed to solve the fragmentation problems shown in the other photos. These problems begin where rare plants and animals are cut off from others of their kind, he explained.

Mr. LEVEY: And when that happens, the animals and plants will start inbreeding and that will reduce their genetic viability. Also, when populations are fragmented, they are much smaller, obviously, than a very large population and are more prone to extinction events that happen by chance.

NIELSEN: Like a hurricane or a disease. Levey thinks these risks can be reduced by natural corridors. He built his giant study site to prove that animals actually use these corridors. He made it easier to follow his two study species, wax myrtles and Eastern bluebirds, by doctoring the fruit they ate.

Mr. LEVEY: We sprayed that fruit with fluorescent powder, a very dilute solution of it that the bluebirds couldn't see and that wouldn't hurt them.

NIELSEN: Levey and an army of unlucky students spent the next several years crawling through the bushes looking for fluorescent bird poop. In the end, they found 13,000 samples. They found most of them in the corridor. David Wilcove, a professor of ecology at Princeton University, says this is the kind of study that could actually convince more people to build more corridors.

Professor DAVID WILCOVE (Princeton University): It's better than studying a bunch of animals, a bunch of insects bouncing around in a shoe box. It's not quite at the scale of studying the movement of tigers between parks in India but it's getting closer to that larger landscape level.

NIELSEN: Levey says researchers are already tracking the movements of other species out on his study site, ranging from rare insects to unwanted plants and animals. John Nielsen, NPR News, Washington.

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