Bats Endangered by Deadly White Nose Syndrome

White Nose Syndrome (WNS) is a devastating disease that has afflicted several species of bats in the eastern United States and is rapidly spreading. It was first discovered near Albany, New York in February of 2006 by a caver who observed hibernating bats with white muzzles, and also noticed some dead bats in the cave. Since that time, over 400,000 bats in nine states have died of the syndrome. Colonies in some affected caves have been reduced by up to 97%.

The name White Nose Syndrome comes from the observation that infected bats often have a white ring around their muzzle, as well as white patches on their ears and wings caused by fungal growth. The fungus that is believed to cause the disease has recently been identified and named Geomyces destructans. It is a cold-loving fungus, able to grow at 40 degrees F, the temperature of caves where bats hibernate during the winter.

When bats hibernate, they lower their body temperature until it is close to the air temperature of the cave, and their immune system slows down, making them targets for infection by the fungus. Many of the infected bats awaken too early from hibernation and leave their hibernacula (caves where they hibernate) during the winter. They lose their fat reserves and become emaciated, and with no insects available to eat, they starve to death.

White Nose Syndrome is spreading rapidly through the northeast and Mid-atlantic states. It has now been identified in New York, Vermont, Massachusetts, Connecticut, New Hampshire, New Jersey, Pennsylvania, Tennessee, West Virginia, and Virginia, and there is a danger that it may spread to the Midwest. The US Fish and Wildlife Service reports that as of June, 2010, it has been confirmed in parts of Canada, and is likely in Oklahoma and Missouri.

According to a USGS report, there are 25 species of hibernating bats in North America, four of which are endangered: Indiana bats (Myotis sodalis), gray bats (Myotis grisescens), Ozark big-eared bats (Corynorhinus townsendii ingens), and Virginia big-eared bats (Corynorhinus townsendii virginianus). The U.S. Fish and Wildlife Service estimates that the population of endangered Indiana bats in the Northeast Region has declined by 30% since 2007. In addition to these endangered species, several other species of bats have also been affected, including little brown bats (Myotis lucifugus) and northern long-eared bats (Myotis septentrionalis).

While bats have sometimes been erroneously regarded as frightening or dangerous, they are in fact one of the most ecologically important and beneficial mammals. They are the primary predator of night-flying insects, and a bat can eat half its weight in insects in a night, sometimes consuming up to 600 insects in one hour. A colony of bats can eat thousands of pounds of insects in a season, thereby keeping down the populations of harmful insects such as mosquitoes and agricultural pests.

At this point, scientists are not optimistic about being able to find a cure for White-Nose Syndrome. While research is underway to characterize the fungus and understand the mechanism of the disease, the main focus at present is to prevent it from spreading and leading to an ecological catastrophe.

Evidence suggests that human activity may contribute to the spread of the disease. Cavers who visit infected caves may cause the fungal spores to spread, or carry them on contaminated caving equipment from one cave to another.

The U.S. Fish and Wildlife Service has issued an advisory requesting a voluntary moritorium on caving activity in all states affected by WNS as well as adjacent states, in an effort to curtail the spread of the disease. Recreational caves have been closed in infected areas of Virginia.

To learn more about White-Nose Syndrome and its effects, see the U.S. Fish and Wildlife Service fact sheet, and visit the District of Columbia Grotto of the National Speleological Society's very informative web page.