DAVID GREENE, HOST:
So a losing battle for ducks - onto another battle involving bats. They're flower pollinators, and they devour nuisance insects. But millions of bats have been killed by a disease called white-nose syndrome. But as North Country Public Radio's Brian Mann reports, some bats are bouncing back.
BRIAN MANN, BYLINE: When I first visited Aeolus Cave in Vermont's Green Mountains six years ago, the floor was carpeted with tiny bodies and delicate bones. Scientists like Scott Darling with Vermont's Fish and Wildlife Service were shaken by the carnage.
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SCOTT DARLING: This is just far more than I expected. It's way more - so many more dead bats here.
MANN: That was 2009. Scientists say a quarter-million animals died here, many of their tiny faces crusted with the white fungus that gives this disease its name. So on my latest trip to the cave, the first bit of good news is that bats are still living here. The population is much smaller. But as I crawled through the gap of mud and rock into darkness, my headlamp falls again and again on living bats, clinging to the roof.
JONATHAN REICHARD: It's a little bit of a curveball to be here today, you know, six years after being here and seeing all the dead bats, to think that there are still bats in there.
MANN: Jonathan Reichard is national assistant coordinator for white-nose syndrome for the U.S. Fish and Wildlife Service. Like a lot of scientists, he feared that this disease might exterminate the animals entirely, sweeping them from large parts of North America. On this night, Reichard is part of the team catching bats, inspecting them. Listen closely, and you can hear the flutter of their wings, their tiny squeaks. To guys like Reichard, that's the sound of hope, especially for a type of bat known as the little brown.
REICHARD: The declines in that species have slowed down or even reversed in some cases. There's evidence that colonies may even be increasing at a slight tick.
MANN: There's other good news. While researchers study the tough little holdouts here in Vermont, a wildlife veterinarian at the University of Wisconsin has been cracking the code on how exactly white-nose syndrome kills these animals. The study's lead author, Michelle Verant, says the fungus causes bats' bodies to overheat, burning energy too quickly.
MICHELLE VERANT: The amount of fat energy that bats affected with white-nose syndrome used was twice as much as the healthy bat.
MANN: Verant says hibernating bats begin to starve. Some flee into the deadly cold, searching for more food. Verant thinks her work, funded by the U.S. Geological Survey, could help point the way toward helping more bats, like the ones in Aeolus Cave, survive. Scientists are scrambling to develop targeted fungicides that might kill white-nose outright. In the meantime, Verant says wildlife managers need to make sure bats are healthy and plump before they go into the caves for the winter.
VERANT: The best thing that we can do right now is supporting bats with good habitat and reducing those additional stressors.
MANN: As this disease spreads west, Verant's findings will play big part in the debate over the federal government's response. The U.S. Fish and Wildlife Service is now deciding whether one type of bat, called the northern long-eared, should be added to the endangered species list. That would mean more protections for the forests and caves that bats rely on when building their stores of fat. Last month, Canada's government did just that, adding three types of bats to their list of endangered animals. For NPR News, I'm Brian Mann.