What is the effect of white-nose syndrome on bats?

We have seen 90 to 100 percent mortality of bats (primarily little brown bats) at hibernacula in the northeastern United States. However, there may be differences in mortality by site and by species within sites.

The endangered Indiana bat hibernates in many of the affected sites. We are closely monitoring Indiana bat populations in many hibernacula and, to the extent possible, in their summer maternity colonies. During the winter of 2008-2009, biologists conducted the biennial rangewide winter counts of Indiana bats. Population estimates based on this count show the overall Indiana bat population declined by approximately 17 percent. This is the first observed decline since 2001.

In addition to the Indiana bat, white-nose syndrome has reached the ranges of three more endangered bats: gray bats, Virginia big-eared bats and Ozark big-eared bats. We are closely monitoring these species as WNS continues to spread.