Through my work with the Northeast Fish and Wildlife Diversity Technical Committee, I've had an opportunity to learn more about the disease affecting bats throughout the eastern U.S. One of the best places to go to learn more about the disease is whitenosesyndrome.org - a website dedicated to reporting the latest information as researchers and agency scientists work together to respond to this devastating bat disease.
The disease is caused by a fungus, Pseudogymnoascus destructans. Affected bats show a white fungus on their noses. The disease seems to kill bats by causing them to arouse too often during hibernation - expending too much energy and leaving them drained when they come out of hibernation in spring.
|Tri-colored bat with white nose syndrome symptom. Photo by Darwin Brack via USFWS flickr account.|
White nose syndrome was first observed in New York in the winter of 2006-2007. The disease spread radially from there over the last 9 years and confirmed cases of bats with white nose syndrome have been found in 31 states. Four more states have confirmed the fungus Pseudogymonoascus destructans.
|Map of Bat White Nose Syndrome Occurrence over time (2006-2016) produced by Lindsey Heffernan, Pennsylvania Game Commission via https://www.whitenosesyndrome.org/resources/map|
Seven species of bat in North America have been identified with symptoms of White Nose Syndrome:
- Big brown bat (Eptesicus fuscus)
- Eastern small-footed bat (Myotis leibii)
- Gray bat (Myotis grisescens)
- Indiana bat (Myotis sodalis)
- Little brown bat (Myotis lucifugus)
- Northern long-eared bat (Myotis septentrionalis)
- Tri-colored bat (Perimyotis subflavus)
Each species is impacted by the disease to differing degrees and in different ways based on their particular hibernation conditions (temperature, seasonal duration) and other factors - some species, like tri-colored bat, are experiencing high mortality.
Population declines have been so severe that concern for the affected species is very high. Gray bat and Indiana bat have been federally listed as endangered, and northern long-eared bat is now listed threatened. In the Northeast, little brown bat, eastern small-footed bat, northern long-eared bat, and tri-colored bat are listed as Species of Greatest Conservation Need in all 14 states' Wildlife Action Plans.
|Little brown bat. Photo by J.N. Stuart via Flickr.|
|Northern long-eared bat. Photo by USFWS-Midwest|
Treatments that are effective at eliminating Pseudogymnoascus destructans both on cave walls and on bats' noses have been developed. However, treatment of caves could eliminate many other native fungii with potentially disastrous unintended consequences, and bats could carry the fungus back to the cave every year. Treatment of individual bats is only practical on a small scale - and they could be reinfected every winter. At this time there is no feasible way to prevent this disease in wild populations.
As with any wildlife disease, natural biological responses can eventually control the impact. Bats could adapt to the fungus or other species (plant or animal) could control Pseudogymnoascus destructans through competition or other means. The best stewardship actions humans can provide are not disturbing hibernating bats, not spreading the fungus through our own visits to caves (read about decontamination protocols), and reducing any other stresses on bats - the healthier each individual is, the more likely they would survive a hibernation with white nose.