Mysterious White Nose Syndrome Causes Bat Die-Offs

Bats in the northeast are dying off by the tens of thousands and the experts do not know why. In the winter of 2006-2007, people began discovering dead or dying bats near the entrances to caves – at a time of the year when they should be safely inside and hibernating. Affected animals frequently exhibit a ring of white fungus around the nose, so the mysterious disease has been dubbed “white nose syndrome.” The scientists and wildlife specialists investigating do not know if the fungus, which also can be found on wings, ears and tails of the sick bats, is a symptom of the illness that’s killing them or a sign of a secondary disease that sets in once their immune symptoms are weakened.

White nose has been discovered in about 30 hibernacula (caves and mines with hibernating bat colonies) in New York, Massachusetts, Connecticut, Vermont and possibly Pennsylvania. It affects the small-footed, northern long-eared, eastern pipistrelle, little brown and federally endangered Indiana bats. Little browns, the most numerous hibernating bats in the state, have suffered the largest number of deaths. Thus far, big brown bats appear to be unaffected. The disease somehow depletes a special type of body fat needed to sustain them during hibernation. Affected bats effectively waste away. As a result, they either awake prematurely and leave hibernacula in search of food during winter or never wake from hibernation at all. Investigators are looking into possible causes, including climate shifts, pesticides, bacterial, fungal or viral infections or some combination of these.

Affected sites in New York are in the Hudson River Valley and Adirondack regions, but the die-offs are expected to tax the populations of bats across the northeast because many of the bats migrate hundreds of miles between summer ranges and overwintering sites. The population densities in the hibernacula can be as high as 300 bats per square foot, which probably contributes to the spread of the illness.

The mortality rate was higher than 95 percent in two New York caves studied last year. Experts are requesting that cavers stay out of hibernacula to avoid spreading this perplexing fatal illness. The syndrome does not seem to have an effect on humans, but New York Department of Environmental Conservation (DEC) workers and other researchers are using precautions (sanitary clothing and respirators) to avoid spreading the illness.

“Most bat researchers would agree that this is the greatest threat to bats they have ever seen. We have bat researchers, laboratories and caving groups across the country working to understand the cause of the problem and ways to contain it. Until we know more, we are asking people to stay away from known bat caves,” said Alan Hicks, DEC bat specialist. How these die-offs will influence insect populations and agriculture are another big unknown.

Individuals who witness bats that may be suffering from white nose should report the information to the nearest field office of the Federal Fish and Wildlife Service or to the New York DEC. A directory of FWS offices is at FWS.gov/northeast/offices, and regional DEC contact information can be found at DEC.ny.gov.


by Anya Harris