US Fish & Wildlife Service


Date of this Version



U.S. Fish & Wildlife Service, 2014.


What is white-nose syndrome?

White-nose syndrome (WNS) is a disease affecting hibernating bats. Named for a white fungus that appears on the muzzle and other parts of bats, WNS is associated with extensive mortality of these animals in eastern North America. First documented in New York in the winter of 2006-2007, WNS has spread rapidly across the eastern and midwestern United States and eastern Canada, and evidence of the fungus that causes WNS has been detected as far south as Mississippi.

Bats with WNS act strangely during cold winter months, including flying outside during the day and clustering near the entrances of caves and other hibernation areas. Bats have been found sick and dying in unprecedented numbers in and around caves and mines. WNS has killed more than 5.5 million bats in the Northeast and Canada. In some areas, 90 to 100 percent of bats have died.