MONTPELIER, Vt. - A biologist who has studied the decline in Vermont's bat populations since white nose syndrome started killing tens of thousands almost a decade ago says he thinks the worst of the epidemic is over and at least one affected species is beginning to recover.
Despite the devastation among certain bat species caused by the disease that spread into Vermont out of a New York cave in the mid-2000s, thousands of little brown bats, once the most common bat in Vermont, continue to pass the winter in the Aeolus bat cave in Dorset, said Scott Darling, a biologist with the Department of Fish and Wildlife.
Since white nose was first identified, it has spread across the country and into parts of Canada, devastating new bat populations.
"Here in Vermont, I think we have seen the worst of it," Darling said. "I suspect we are at the beginning of a long road toward recovery."
Jeremy Coleman, the white nose coordinator for the U.S. Fish and Wildlife Service, says biologists in New York have seen similar changes. But in other parts of the country, white nose is continuing to devastate bat populations. Many questions remain about the long-term recovery of the species.
For example, bats can live more than 20 years and it's unclear how well bats that have been exposed to and survived white nose will reproduce.
"There is cause for hope and some optimism for the remnant population, but do we have enough of a remnant population to allow that species to recover?" Coleman asked.
In Vermont, it's unclear whether the bats passing the winter in the cave, known as a hibernaculum, are those that survived exposure to white nose or whether they are uninfected bats that flew to Vermont to hibernate and could still face exposure.
White nose, which has killed up to 90 percent of some species, is caused by a fungus that prompts bats to wake from their winter hibernation and die when they fly into the frigid, insect-less winter landscape. It was detected in New York's Adirondack Mountains in 2006 and since then has been spreading across North America killing at least a million bats.
The fungus is believed to have been brought to North America from Europe, where the fungus is found, but bats are unaffected.
As part of an effort to determine whether the bats in the Aeolus cave are survivors, Darling and other biologists tagged about 450 little brown bats last fall to determine whether they leave the cave during the winter in search of food, a mark of white nose. The bats that leave the caves die because the winter landscape does not provide the insects they need to survive.
Next month, the biologists will be monitoring the cave to see how many emerge from hibernation.
"If, in fact, survivorship is high, maybe there is some genetic or behavioral trait that has enabled these bats to be resistant or resilient to the disease," Darling said.
Darling said the well-known plight of the bats has drawn support from people across Vermont.
"We've got homeowners with maternity colonies in and around their houses, and they're willing to put up with them because they know their situation," Darling said. "If they could just stop being killed by the disease itself, that would be a big step forward."