Bats may lose their fat reserves, which they need to survive hibernation, long before the winter is over. They often leave their hibernacula during the winter and die. As winter progresses, increasing numbers of dead bats have been found at many affected locations.
White-nose syndrome may be associated with some or all of the following unusual bat behavior:
- White fungus, especially on the bats’ nose, but also on the wings, ears or tail;
- Bats flying outside during the day in temperatures at or below freezing;
- Bats clustered near entrances of hibernacula; and
- Dead or dying bats on the ground or on buildings, trees or other structures.
Hibernating bats may have other white fungus not associated with WNS. If a bat with fungus is not in an affected area and has no other signs of WNS, it may not have WNS.