Deadly Bat Disease Continues Rapid Spread as White Nose Syndrome Reaches New States

Bats with white-nose syndrome in Hailes Cave, Albany County, NY. Photo: N. Heaslip/NYSDEC

White-nose syndrome, a deadly disease that has killed more than 1 million bats in four years, has been found in two more states this year—Indiana and North Carolina. Now nine bat species in 16 states have been documented with WNS or the fungus, Geomyces destructans, that biologists say is the likely cause of this disease that has devastated bat populations across the eastern United States.

Wildlife officials aren’t surprised that WNS, named for the cold-loving white fungus that’s usually found on the faces and wings of infected bats, has moved into new territory.

Click map for larger image.

“White-nose syndrome is confirmed in Virginia and Tennessee, so we expected we would be one of the next states to see the disease,” says Gabrielle Graeter, a biologist with the North Carolina Wildlife Resources Commission. “This discovery marks the arrival of one of the most devastating threats to bat conservation in our time.” Little brown bat with the fungus in Hamilton Cave, WV.

Photo: WV Div. of Natural Resources

“We knew WNS was likely to reach Indiana caves this year, and we have been working closely with biologists from the DNR to prepare for this as well as we could,” says Tom Melius, the Indiana Department of Natural Resources’s Midwest Regional Director. “Nonetheless, it is devastating to actually confirm the presence of the fungus and witness the symptoms of WNS in bats. While there is currently no cure and no treatment for this disease, we will put all our energies into contributing to the ongoing efforts to understand and combat WNS.”

The first casualties were discovered in an upstate New York cave during the winter of 2006. Biologists found hundreds of little brown bat corpses with a mysterious white fluff on their noses. Since then WNS has spread to 16 states and killed bats from nine species: The little brown bat, eastern small-footed bat, northern long-eared bat, tri-colored bat, big brown bat, southeastern myotis, cave myotis, and two federally endangered bats: the Indiana bat and the gray bat. The bats are insectivores that help keep pests in check.

“This massive die-off is unprecedented,” Boston University ecologist Thomas Kunz told me for an article in the January-February issue.

From Audubon magazine:

Researchers don’t know if the fungus itself is lethal, though there’s evidence that it weakens bats’ immune systems. It might also irritate their skin, waking them from their winter slumber, or torpor. While healthy bats awaken once every two to three weeks for an hour or two, bats with WNS arouse about every four to five days. “That arousal really burns up fat,” says Kunz, “so bats with the fungus run out of fat, which is deadly.”

Though WNS has decimated some entire colonies, others appear to have stabilized at about a third of their population, possibly because some animals are naturally resistant to the fungus. They still face risks, namely not being able to survive and reproduce because they spend all their energy keeping warm.

To give them a fighting chance, in places with existing colonies Kunz and colleagues are installing bat houses, whose small crevices keep bats warmer than airy barns or caves. “[Bat houses] provide one of the best opportunities for survivors to be reproductively successful, even in a smaller colony.”

Click here to learn about installing a bat house in your yard, like the one pictured to the right (courtesy Bat Conservation International). Big brown bats and little brown myotis are likely to roost in these mailbox-sized structures nationwide; homeowners in the South may attract Mexican free-tailed and evening bats. In addition to providing the pleasure of bat watching, houses might also help protect bats from the deadly white nose syndrome.