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Endangered bat numbers rise, but mysterious illness poses threat

The endangered Indiana bat saw a 9.4% population increase between 2005 and 2007, continuing a twelve-year rise in bat numbers, though a mysterious illness in the Northeast poses a threat to this success.

According figures recently released by the U.S. Fish and Wildlife Service (Service), in 2007 the number of Indiana bats rose to more than 513,000, up from 469,000 in 2005, the last time a comprehensive population estimate was completed.

“While that seems like a lot of bats, every winter they come together in massive numbers in a few caves and mines to hibernate, making them extremely vulnerable. In the past, human disturbance of major Indiana bat hibernation sites significantly contributed to the bat’s decline and was a main factor leading to its addition to the Federal list of endangered species. Now the bat’s habit of aggregating in large numbers at hibernation sites may make them more vulnerable to the rapid spread of this new disease.” said Robert Currie, a bat biologist in the Service’s Asheville Field Office.

Biologists in New York documented the death of thousands of bats, including several hundred Indiana bats, all apparently infected by a fungus which often forms white tufts on the bats’ muzzles, giving the name white nose syndrome, or WNS. In addition to the white muzzle, dead bats appear to have used up their winter fat stores and have congregated much closer to cave entrances than usual. Researchers are trying to determine if the fungus itself is responsible for the deaths or if its presence is symptomatic of another problem.

Although they occur in greatest numbers in the Midwest, Indiana bats have been known to hibernate in Western North Carolina, and more commonly, migrate to the region in the warmer months. Thus far, white nose syndrome has only been documented in New York and Vermont and until they have a better understanding of the nature of the disease and how it’s transmitted, biologists urge cavers to help prevent its potential spread. To that end, the Service provides these recommendations:

  • Do not touch any bats (living or dead), especially those with a white muzzle/nose.
  • If you are in a cave and see bats with white muzzles or noses, exit the cave immediately, avoiding contact with other bats, and please do not enter any other caves prior to decontaminating your clothing and gear.
  • Contact your state fish and wildlife agency or your nearest Service Field Office to report your potential WNS observations.
  • Report any dead bats found outdoors or any unusual numbers of bats outside during cold weather, especially near a cave or mine where bats hibernate.

Decontaminate your clothing and all caving equipment following these procedures:

  • Remove your caving gear when you get to the vehicle and put it in a closed plastic/garbage bag to prevent contamination of the interior or trunk.
  • Wash caving clothes using hot water, detergent and a normal bleach cycle.
  • Dry the clothes thoroughly and dry them at hot temperatures.
  • Scrape the dirt from boots and soak them in a 10% bleach solution (1 part chlorine bleach, 9 parts water) – soak porous boots longer than nonporous boots.
  • Do not forget to wash or soak cave packs and to thoroughly clean helmets/lights with a 10% bleach solution or a similarly effective disinfectant.

Additional information about white nose syndrome and Indiana bats can be found at


  • Robert Currie, U.S. Fish and Wildlife Service, (828) 258-3939, ext. 224

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