What Is Killing the Bats?

Can scientists stop white-nose syndrome, a new disease that is killing bats in catastrophic numbers?

In the worst animal epidemic in years, white-nose syndrome threatens to wipe out some bat species. (Lynda Richardson)
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Later that winter, during a routine cave survey, New York State biologists found thousands of dead bats in a limestone cave near Albany, many encrusted with a strange white fuzz. During the winters that followed, dead bats piled up in caves throughout the Northeast. The scientists would emerge filthy and saddened, with bat bones—each as thin and flexible as a pine needle—wedged into their boot treads.

By the end of 2008, wildlife-disease researchers had identified the fuzz as a fungus new to North America. Today the fungus has spread to 19 states and 4 Canadian provinces, and infected nine bat species, including the endangered Indiana and gray bats. A 2010 study in the journal Science predicted that the little brown bat—once one of the most common bat species in North America—may go extinct in the eastern United States within 16 years.

“When it first hit, I thought, ‘OK, is there anything we can do to keep it within this cave?’” remembers Hicks. “The next year it was, ‘Is there anything we can do to secure our largest colonies?’ And then the next year it was, ‘Can we keep any of these colonies going?’ Now we’re asking if we can keep these species going.”

G. destructans also infects bats in Europe—but it doesn’t kill them, at least not in large numbers. G. destructans may have swept through European caves in the distant past, leaving only bats that could withstand the fungus. Researchers don’t know when and how the fungus made its way to North America, but they speculate that it may be so-called “pathogen pollution,” the inadvertent human transport of diseases—in this case possibly by a cave-visiting tourist—into new and hospitable habitats.

With their undeserved association with creepy folk tales, bats don’t have much of a constituency. But bat biologists say the consequences of the North American die-off stretch far beyond the animals themselves. For instance, one million bats—the number already felled by white-nose syndrome—consume some 700 tons of insects, many of them pests, every year. Fewer bats mean more mosquitoes, aphids and crop failures. A study published in Science this spring estimated that bats provide more than $3.7 billion in pest-control services to U.S. agriculture every year.

With G. destructans reaching farther each winter, Barton, Slack and an array of other biologists are racing to understand the fungus in time to contain it. Since scientists aren’t sure how easily people may spread the fungus, many caves have been closed, and tourists, recreational cavers as well as scientists are advised to clean their gear between trips underground. Barton and her students have shown that common cleaning products, such as Woolite and Formula 409, kill G. destructans without harming caving gear.

But even as Barton, Slack and their colleagues patrol the perimeter of the disease, they acknowledge that the syndrome is likely to continue its spread across the continent.

“Who’s going to live, and who’s going to die?” asks DeeAnn Reeder. “That’s the big thing I think about all the time.” Reeder, a biology professor at Bucknell University in central Pennsylvania, spends her days surrounded by white-nose syndrome. G. destructans thrives in nearby caves and mines, on many of the bats in her campus laboratories, and even on a set of petri dishes secured in an isolated laboratory refrigerator. Up close, the epidemic is more complicated than it first appears, for some bat species—and some individual bats—are proving more resistant than others. Reeder wants to know why.

Reeder never expected to study white-nose syndrome, but like Barton, she was perfectly prepared for the job. Fascinated by mammals since her childhood summers in the Sierra Nevada, she studied primate physiology and behavior before switching to bats. At first, the reasons were practical—bats were easy to catch and sample in large numbers—but “I just fell in love with them,” Reeder says. “They’re so tough. I’ve always said that nothing will take them down, that they’re completely resilient. And then we got this fungus,” she says, shaking her head. “It caught us all off guard—and it caught them off guard, too.”

After Reeder came to Pennsylvania in 2005, she outfitted her laboratory with a set of climate-controlled chambers designed to mimic natural cave conditions. She and her students had just begun to collect data on bat hibernation patterns when white-nose syndrome emerged. Suddenly, biologists all over the continent had questions about how bats behaved during hibernation, and Reeder was one of the only researchers well-positioned to answer them. “They’d say, ‘What do we know about hibernation?’ and I’d say, ‘Well, we know this much,’” says Reeder, holding a finger and thumb close together.


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