Unexplained "White Nose" Disease Killing Northeast Bats

Thousands of hibernating bats are dying in caves in New York and Vermont from unknown causes, prompting an investigation by the New York State Department of Environmental Conservation, DEC, as well as wildlife agencies and researchers around the nation.

The most obvious symptom involved in the die-off is a white fungus encircling the noses of some, but not all, of the bats.

Bat with white nose syndrome (Photo courtesy West Virginia Association for Cave Studies)

Called "white nose syndrome," the fungus is believed to be associated with the problem, but it may not contribute to the actual cause of death. It appears that the impacted bats deplete their fat reserves months before they would normally emerge from hibernation, and die as a result.

"What we've seen so far is unprecedented," said Alan Hicks, DEC's bat specialist. "Most bat researchers would agree that this is the gravest threat to bats they have ever seen."

Last year, some 8,000 to 11,000 bats died at several locations in New York, the largest die-off of bats due to disease documented in North America. This year, an unknown number of bats are at risk.

"We have bat researchers, laboratories and caving groups across the country working to understand the cause of the problem and ways to contain it," said Hicks. "Until we know more, we are asking people to stay away from known bat caves."

Craig Stihler, a bat specialist with the West Virginia Department of Natural Resources, says, "The fungus has been identified to the genus Fusarium, a common and widespread genus usually associated with plants. Pathologists that have examined the carcasses recovered from the New York sites do not believe the fungus is the main culprit. One guess at this time is that the fungus invades after the bats are stressed by some other factor."

Bat biologists across the country are evaluating strategies to monitor the presence of the disease and collect specimens for laboratory analysis. Biologists are using sanitary clothing and respirators when entering caves to avoid spreading the disease in the process.

"Our primary concern is to limit the disease from spreading further to other caves and mines that have larger numbers of hibernating bats," said Scott Darling, Vermont state wildlife biologist. "Here in Vermont, the disease has been documented in Morris Cave in Danby, and we will be checking other caves and mines."

Bat populations are particularly vulnerable during hibernation as they congregate in large numbers in caves - in clusters of 300 per square foot in some locations - making them susceptible to disturbance or disease.

Because these bats then migrate as far as hundreds of miles to their summer range, impacts to hibernating bats can have significant implications for bats throughout the Northeast.

"Bats from a cave in Dorset, Vermont have been documented traveling in the spring as far as Rhode Island and Cape Cod," says Darling.

The vast majority of the hundreds of thousands of bats known to hibernate in New York do so in just five caves and mines. Because bats migrate as far as hundreds of miles to their summer range, impacts to hibernating bats can have significant implications for bats throughout the Northeast.

Indiana bats, a state and federally endangered species, are perhaps the most vulnerable. Half the estimated 52,000 Indiana bats that hibernate in New York are located in just one former mine - a mine that is now infected with white nose syndrome.

Eastern pipistrelle, northern long-eared and little brown bats are also dying. Little brown bats, the most common hibernating species in the state, have sustained the largest number of deaths.

DEC has been working closely with the Vermont Fish and Wildlife Department, the U.S. Fish and Wildlife Service, the Northeast Cave Conservancy and the National Speleological Society, along with other researchers from universities and other government agencies.

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