Ecological Investigations of White-Nose Syndrome in Bats

Science Center Objects

White-Nose Syndrome (WNS) is a devastating disease that threatens the survival of hibernating bats in North America. Since first documented in the winter of 2005/2006, WNS has spread from a very small area of New York across at least two thousand kilometers in half or more of states and provinces in the U.S. and Canada. Over five million bats are estimated to have died during the past decade from WNS, and all four federally listed endangered species and subspecies of hibernating cave bats are in harm’s way.

The sudden and widespread mortality associated with WNS is completely unprecedented in hibernating bats and it is not anticipated that their populations will recover quickly, if at all.

Little Brown Bat with white-nose syndrome

A little brown bat with white-nose syndrome. USGS photo.

An additional 19 species of hibernating cave bats occur in the United States and, considering available information, all are potentially susceptible. WNS is named for the ubiquitous presence of a newly identified species of cold-loving fungus (Pseudogymnoascus destructans) that is capable of penetrating and infecting the skin and wing membranes of bats during hibernation. It is critical that research efforts directed toward WNS incorporate the expertise of scientists familiar with the ecology of bats and hibernation physiology.

There are three primary objectives to this project as follows: continue to help coordinate research efforts directed toward white-nose syndrome at a national level and provide technical support on aspects of bat ecology to USGS researchers and others in the scientific and resource management community; assess the possible behavioral mechanisms by which skin infection from the causative fungus specifically acts to cause bat mortality; assess the possible physiological mechanisms by which skin infection from the causative fungus specifically acts to cause bat mortality.

There is now strong evidence that the fungus Pseudogymnoascus destructans is an exotic/invasive species experiencing ecological release in new ecosystems. Based on recently completed and ongoing studies at the USGS National Wildlife Health Center and other laboratories, the cold-loving fungus is now considered the primary causative agent of WNS. However, the disease etiology is unusual because it likely involves the fungus causing aberrant behaviors or disruptions in the unique physiology of wintering bats, rather than typical pathological effects, such as organ failure. Collaboration between USGS disease specialists and bat ecologists is helping bridge gaps in understanding that allow us to rapidly make progress in better addressing this unprecedented disease. The novel video surveillance systems developed by USGS researchers and their partners for deployment in bat hibernation sites have functioned well over entire winters and allowed new types of data to be collected. Video data resulting from this work are beginning to reveal the previously undocumented behaviors of hibernating bats and are offering insight into hibernation behaviors that might help bats survive fungal infection. Physiological studies have documented electrolyte depletion in WNS bats and led to support of the USGS-formulated hypothesis that dehydration plays a major role in the susceptibility of bats to P. destructans. Ongoing mathematical modeling is revealing that humidity of bat hibernacula likely has a major influence on the ability of certain species to survive WNS and may possibly explain why European bats are less susceptible to fungal infection.