Biologists discover deadly bat disease in Md. cave

Biologists have found what they believe is the first evidence that Maryland bats are now infected with white nose syndrome, a deadly fungal disease that has killed more than a million hibernating bats since 2006, devastating colonies from New England to Virginia.

A state biologist conducting a bat survey last Friday found dead and weakened bats in a cave on private property near Cumberland, the Department of Natural Resources reported Wednesday. About three-quarters of the winged mammals had the tell-tale white fungus on their muzzles and other exposed skin.

"It's likely going to kill a majority of them before spring," said Dan Feller, the western region DNR biologist who found them. Typically, once the disease is established in a colony, 90 percent of the bats are gone by the second year.

The dead bats, and samples of the fungus, have been sent to the National Wildlife Health Center, in Madison, Wis., for tests. Results are expected in several weeks.

The discovery was no surprise. White nose syndrome has been creeping steadily south, east and west from the caves near Albany, N.Y., where it was first seen in 2006. Scientists aren't sure how it is being transmitted. Bat-to-bat contact is an obvious possibility, but the fungus' rapid spread has also implicated human cave explorers, who may carry the fungal spores on their clothing or equipment.

Last spring the fungus appeared for the first time among hibernating bats in Pennsylvania, Virginia and West Virginia. This spring it has been found for the first time in Maryland and Tennessee.

The U.S. Fish and Wildlife Service has asked people to stay out of caves in all 11 states where white nose syndrome is established, as well as in adjacent states. Authorities are asking people to avoid all caves during the bat hibernation period, from September through May.

Scientists have speculated that the disease was slow to come to Maryland because the state's relatively small caves don't attract many cavers.

Its discovery here was a blow to those who have worked on the problem for several years, hoping the state might somehow be spared.

"It's hard to take in," said Feller, who had never before seen an infestation in person -- he had avoided caves in affected states out of concern that he might inadvertently bring the fungus back to Maryland.

"I have to admit I was in shock," he said. "I had to get my wits about me to be able to take data."

Feller said he and another biologist had visited the Allegany County cave a month ago, after a nearby resident reported seeing a bat in flight in mid-day. It is a highly unusual sighting in winter, and something that has been reported near bat caves newly infested by the white nose fungus.

"I did an entrance survey and saw one bat, and no sign of white nose syndrome," Feller recalled. But he put the cave at the top of his list for the annual survey.

That survey was delayed several weeks by heavy snow, but Feller and a volunteer assistant finally returned to the Allegany cave last Friday. "As soon as we got to the cave entrance, we noticed a couple of dead bats," he said.

"That was not too alarming," he said. But as they moved into the entrance they began to notice fragmentary bat remains -- evidence of predation on fallen bats, he said. "A nearby log was covered in blood. Something had been there eating all the dead bats."

He also began to find the animals much closer to the cave entrance than is normal in winter.

"When we started looking at the remaining bats that were alive, the majority had the fungus, many around their muzzles, or any bare skin on their forearms, wings and tails," he said. Several hundred were visibly infected.

Although tests to confirm that the fungus is the suspect Geomyces destructans are still pending, Feller said, "I knew exactly what I was dealing with. I don't have any doubt."

The fungus linked to the illness is a cold-loving organism new to science. It's not yet clear how it kills bats. But it appears to disturb them enough during hibernation that they begin to burn off too much fat, awaken early and begin to fly, exhausting themselves weeks before there is enough food to sustain them.

The fungus is not a threat to humans. But the loss of substantial numbers of bats would mean that more of the billions of insect pests they consume each year will survive. Feller said the losses will also impact other cave-dwelling insects, crustaceans and other species that depend on the bats, their bodies and droppings for their sustenance.

Bats most affected are the cave dwelling species, including the very common little brown bat, the less common northern myotis, and the state-endangered small-footed myotis.

It's still unclear how the fungus might affect bat species that roost in man-made structures, or in trees and migrate south for the winter, Feller said. "It's not that Maryland is going to lose all of its bats, but the majority of our species are cave-dwelling."

Some individual bats do seem to survive the infestations. They have been found in summer with skin lesions, and even holes in their wings caused by the infections. Scientists do not yet know whether the survivors have a natural resistance to the infection that might allow them to repopulate.

"But what has been seen farther to the north has been that by the second year of infection of the site, you can expect mortality of 90 to 100 percent," Feller said. In the Allegany cave, "It's likely all the bats already have the fungus on them."

Discovery of the disease has briefly halted the survey.

"We've had to rethink how we're going to do that," said Dana Limpert, a bat biologist with the DNR's Wildlife Services. "We have to follow very strict decontamination protocols ... to ensure that there's no possibility of contamination from us." The survey is expected to resume next week.

There are fewer than 10 important bat hibernacula in Maryland caves, mines and tunnels that get inspected each spring. Most are gated, or on private property. Limpert described the Allegany cave as a medium-sized hibernaculum compared with the others.

The largest hibernaculum in Maryland is the Indigo Tunnel, an abandoned rail tunnel above the Potomac River near Little Orleans, in Allegany County. It is being considered for inclusion in a $4.6 million extension of the Western Maryland Rail trail.

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