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A disease that's devastated the bat population on the East Coast is moving west and fast. And given that bats eat insects, that could have negative repercussions on the region's ecosystem and agriculture. Yellowstone Public Radio's Kayla Desroches reports.
KAYLA DESROCHES, BYLINE: White-nose syndrome, a fungal disease that biologists first found in bat populations in New York in 2006, has been marching west at a rate of roughly 200 miles a year. The cold-weather fungus infects hibernating bats. It's devastated populations in eastern North America. Emily Almberg, an ecologist with Montana Fish, Wildlife and Parks, says they got some bad news when they visited Azure Cave, Montana's biggest bat hibernation site, in May.
EMILY ALMBERG: When the crew went back this year, they did see evidence of a large number of dead bats, and they found about 30 or 40 bats on the cave walls. Historically, they have gone in around the same time and done counts - you know, 17 to 1,900 bats. So just that single comparison of pre versus post suggests there's been a big change.
DESROCHES: A change on the order of a greater-than-90% die-off in one year. Biologists don't have very exact data on hibernating bat populations over time at most sites, which is part of what made Azure Cave so rare in the West. Unlike in Northeastern states, bats here winter in more scattered populations, making them harder to track.
ALMBERG: We don't have absolute count information about any of our bat species, and that's, you know, a struggle, so we don't know exactly what we're starting with.
DESROCHES: They do know that bats play an important role in the ecosystem, feeding on massive amounts of insects. A little brown bat can eat more than half its body weight in bugs each night. One paper estimates the decline in bat populations cost U.S. agriculture half a billion dollars a year. Almberg says there are less tangible losses too.
ALMBERG: You know, these are long-lived mammals in some cases, and they're social. And you think about, like, you know, the potential cultural knowledge that a community of bats has of the landscape, and we're poised to lose a lot of that. It's a shame.
DESROCHES: Conservationists who track bat populations in the Eastern and Central U.S. say white-nose syndrome wiped out the majority of populations they were monitoring, including the little brown bat.
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DESROCHES: Almberg and fellow researchers captured bat calls like this one in a forest clearing recently and processed them on a computer so humans can hear them.
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DESROCHES: It's part of acoustic surveys biologists across North America are doing to map bat populations and track them over time for the collaborative North American Bat Monitoring Program. Researchers, meanwhile, are looking for ways to interrupt the spread of white-nose syndrome. Jeremy Coleman is a biologist with the U.S. Fish and Wildlife Service.
JEREMY COLEMAN: We're working with a group in British Columbia and in Washington state to deploy probiotics, which are microbes that can be put on bats that have antifungal properties that can help them to repel the fungal infection. We're also working with the U.S. Geological Survey to develop a vaccine.
DESROCHES: To date, 38 states have reported cases of white-nose syndrome. Even more have found the fungus, most recently in Idaho and Colorado. The fungus and disease remain unconfirmed in a cluster of Southwestern states. The U.S. Fish and Wildlife Service proposed to reclassify the northern long-eared bat as endangered in March due to white-nose syndrome and will announce its decision in November.
For NPR News, I'm Kayla Desroches in Billings.
(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.
