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Broken Bats

A mysterious disease that has killed thousands of bats may have settled in Western Pennsylvania caves

click to enlarge A cluster of bats exhibiting an unexplained (and possibly deadly) white fungus on their noses. - COURTESY OF NEW YORK DEPARTMENT OF ENVIRONMENTAL CONSERVATION
Courtesy of New York Department of Environmental Conservation
A cluster of bats exhibiting an unexplained (and possibly deadly) white fungus on their noses.

Researchers across the state are keeping a close watch on Pennsylvania's caves this winter for signs that a mysterious New England bat plague could be moving south.

In the past two years, tens of thousands of bats in Vermont, Connecticut, Massachusetts and New York have died. And while the death toll is staggering, the scariest part is that biologists can't say for sure what's killing the flying mammals.

"This is something totally new and unexpected," says Aura Stauffer, of Pennsylvania's Department of Conservation and Natural Resources (DCNR). "It was quite frightening when it was found up in the north."

Scientists are calling the unknown killer "white-nose syndrome" because of a white fungus that has appeared on the wings and muzzles of many of the dying bats.

Pennsylvania wildlife experts are already investigating several suspicious cases -- where bats have shown similar symptoms to the New England bats -- though no bat deaths in the state have been linked to the problem.

Stauffer says that city bats, the kind you will most likely find in someone's attic, are usually big brown bats, which have generally been more resistant to white-nose syndrome.

White-nose does not appear harmful to humans, though it is devastating to bats.

Without knowing what exactly white-nose is, or how it is spread, officials have been powerless to stop it. The first known case was discovered by researchers outside Albany, N.Y., and documented by the New York Department of Environmental Conservation in January 2007.

"It was our last trip" of the 2006-07 winter season, state biologist Al Hicks told fellow bat researchers at a Scranton convention on Oct. 25. "It was also the only winter survey that I did not participate in [during] my entire career. I stayed at my desk to write a report.

"That will never happen again. I can guarantee you."

Losing insect-eating bats in these numbers could impact the natural balance that exists in wooded areas. For people like Hicks, the original puzzle outside Albany has evolved into a nightmare.

"This was a fairly new crew," he said at this year's North American Symposium on Bat Research, retelling the story that started it all. When the researchers came back, "one of them happened to say, 'Well, you know, I've never happened to see any of that white stuff on the bats. How common is that?' And I said, 'What white stuff?'"

The researcher produced a photograph of several bats with the mysterious white fungus.

"He pulled this picture out. And I almost literally fell out of my chair," Hicks said. "[I] immediately got on the phone and started calling everybody and their grandmother. Within a few days, this photograph was everywhere. We knew it was something very bad and very unusual."

In some instances, white-nose syndrome has been credited with wiping out entire caves of bats.

"Our bats are dying in absolutely unprecedented numbers. There's no question about it," Hicks said at the conference. "What also looks bad is that there seems to be no evidence of resistance to this problem. It appears that the bats that lived through the first year were just lucky."

Last winter, Hicks said, they found evidence of the disease 120 miles from the original site. "If current trends continue, we expect white-nose to involve most North American hibernacular areas in the eastern part of this country in the next few years."

Getting rid of bats may sound fine to some people: The flying mammals are known to carry diseases like rabies. They are also the subject of many myths and a common phobia.

But "bats are an important part of the ecosystem," says the DCNR's Stauffer. "They eat a lot of insects."

Additionally, among the species of bats afflicted by white-nose is the Indiana bat (myotis sodalis), one of the state's endangered species.

In June, the DCNR announced in a press release that it was closing Barton Cave in Fayette County for the rest of the year "to give biologists more time to study possible preliminary signs of a mysterious bat ailment."

The release reiterated that "the bat ailment has not been confirmed in Pennsylvania, but during routine visits [to caves in Fayette, Luzerne and Blair counties], Game Commission officials discovered a white fungus similar to that on bats afflicted with the disease in Vermont and New York."

Stauffer says the officials have nothing to report yet. The bats are just now wrapping up their fall swarm and mating period. Soon they will go into hibernation. If white-nose has taken hold in Pennsylvania, that's when it will strike.

In the meantime, unlocking the white-nose puzzle has become a collaborative effort, with federal, state and educational institutions pitching in.

While the fungus is the most visible symptom, many bats with the problem also exhibit other unusual behavior. "In the middle of winter, when the bats should be hibernating, they're waking up," Stauffer says. "Something's keeping them awake for longer periods of time." Once awake, the bats' metabolism speeds up, requiring them to feed. But because of the cold, "there are less insects, so they're starving to death."

At the conference in October, Elizabeth Buckles, a veterinary pathologist at Cornell University, explained what her team has figured out so far after performing autopsies on some 200 dead bats from New England.

"One thing we're finding is that the vast majority of the little browns, [a common species of bat, are] light," Buckles said. Typically, little browns are "little butterballs," she added, with fat accounting for 10 percent of their body weight.

But white-nose bats are coming in underweight. And while it's the discoloration of the nose that is most notable, Buckles said, "[P]athologists are more worried about the wing damage, starting to see strange spots on the wings, pieces of wings missing.

"So damaged-wing syndrome might be a better [name], but it's not as cool-sounding."

Buckles said that there are currently three main hypotheses for what's happening. The first is that the fungus itself is to blame. "It's coming in, we don't know why, and it's killing the bats," she said.

The second theory is that the fungus is just a side effect, that it is "actually coming because there's something else wrong with the bat." Viruses that attack the immune system -- like HIV in humans -- can make an organism more susceptible to other infections.

Buckles' third hypothesis is a combination of the first two: The fungus is attacking the bats in concert with some other infection.

"This is the most likely scenario," she said. "Certainly this looks like an infectious disease the way it's spreading, but as we progress in our disease investigation, we have to keep an open mind."

For one thing, there's still much that they don't know about hibernating bats.

During the winter, bats enter a state of torpor. Their temperatures and metabolism rates drop to preserve energy. It's unclear what effect this has on a bat's immune system, Buckles said.

"One of the questions is, 'Why are these bats not responding to fungal invasion in their skin?'" she added. "I can tell you as a pathologist, that after days with any mammal, you're going to start seeing pus form [a sign that the body is fighting the infection]. ... I don't think anyone knows if those rules apply to a hibernating animal."

For now, conservation experts in Pennsylvania can only sit back and hope the bats survive. Game Commission biologist Greg Turner surveyed some of the bats going into the caves this autumn, and he'll check them again at the end of winter.

There are signs of optimism, though caution remains the word of the day.

"There wasn't any evidence of bats dying this fall," Turner says. "All things looked pretty good, considering. ... It's tough to make any concrete statements about it, but basically they looked fat and healthy to me."

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