DFW Staff examine bat hibernacula
DFW Staff examine bat hibernacula

White-nose Syndrome (WNS) is the descriptive term given to a condition first observed in bats hibernating in a cave near Albany, NY in February 2006. The term comes from the fact that some of the bats with this condition look like they dipped their faces in powdered sugar. The white powdery substance on their faces is a fungus. On closer examination, this white fungus can also be seen on the bare skin of their ears and wings. In 2009, this fungus was described as a newly discovered species and named Geomyces destructans to highlight the harm that it is causing to North American bats.

At caves and mines with WNS, some of the bats hibernating over the winter run out of body fat by early February and can be seen flying outside around in the daytime in a desperate attempt to find something to eat. Hibernating bats should have enough fat to last them through the winter so that when they come out in late April and May, there will already be insects to eat. Unfortunately, any bat that runs out of body fat too early or leaves its hibernation site when night-time temperatures are still falling below freezing, is doomed. At the largest Massachusetts bat hibernation site in a mine in Chester, there were about 10,000 bats in early winter 2007/08, but by the end of winter 2008/09 nearly every bat had been killed by WNS; only 14 bats were left.

White-nose Syndrome has spread rapidly and has caused the catastrophic mortality of bats that spend the winter in New England caves and mines. By 2009, nearly half a million bats had died from WNS in the northeastern states from Vermont south to Virginia. By 2013, over 2 million bats had died at sites from eastern Canada, south to Alabama, and west to Oklahoma. At this point, no one knows how to stop or even slow the continuing spread of WNS, and no one can predict just how far it will eventually go and how many bats will die in the process.

Little Brown Bat with White-nose Syndrome.  Photo by Bill Byrne.
Little Brown Bat with White-nose Syndrome. Photo by Bill Byrne.

As a result of the devastating mortality that has resulted from WNS in Massachusetts, all four of our bat species that spend the winters in caves or mines have been listed as Endangered. This includes the Little Brown Bat, which used to be the most abundant species of bat in the Commonwealth. The other species are the Northern Long-eared Bat, Small-footed Bat, and Tri-colored Bat (formerly known as the Eastern Pipistrelle). The Indiana Bat was already listed as Endangered as a result of impacts from the pesticide DDT, and was last seen in our mine in Chester in 1939. The only two Massachusetts bats that have summer colonies in houses are the Little Brown Bat and the Big Brown Bat. Most of the Little Brown Bat colonies are now gone, but Big Brown Bats have not been seriously affected because most hibernate in cold, dry attics where the WNS fungus does not grow. The few Big Brown Bats that did hibernate in cold, wet caves and mines have already died. There are also three species of “tree bats” in Massachusetts that migrate south for the winter. These bats, the Red Bat, Hoary Bat, and Silver-haired Bat, are not exposed to the WNS fungus.

To help us better understand WNS, please report observations of bats flying in the winter, (January-March) and let us know if you have a summer colony of bats. If you have a summer colony, please report where it is, what kind of place it is in, and about how many bats are in the colony. Your help is greatly appreciated.