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|August 7-13, 2008
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Bat illness baffles scientists
A mysterious disease is killing bats and no one knows why
by Andy Mead
Two rabid bats were found in Lexington, Ky. this month, stirring the wave of uneasiness that humans have long felt toward our tiny flying mammal cousins.
But the people who study bats say we should be less concerned about what bats might do to us, and more worried about a mysterious disease that is killing them, and what that might mean to us and our entire ecosystem.
It was just getting dark on a recent evening when the first bat slipped out of an expansion joint beneath a small bridge in Jessamine County, Ky., flew in a couple of graceful ovals, then headed out for a night of feasting on insects.
Soon another bat emerged, then another and another and another. It was a maternity colony, so the bats were mothers and their youngsters, perhaps a couple of thousand in all.
They were gray bats, a species that is officially listed as endangered, but which has been doing quite well in recent years.
An adult gray has a wingspan of 10 to 11 inches, but is so delicate that it weighs less than three U.S. quarters. It can live for 25 to 30 years.
Mark Gumbert, a biologist whose Copperhead Environmental Consulting was in the area to survey bats, was standing under the bridge, enjoying the remarkable show. He knew of the recent reports of rabid bats, but was not afraid.
Many bats passed close to his head, using their built-in radar to avoid his brown curls.
“This is normal bat behavior,” Gumbert said. “But when the general public sees a bat flopping around on the ground in the daytime, there’s usually something wrong with it.”
Gumbert has worked closely with bats for 15 years and says he has never seen one he thought was rabid. But bats are wild animals and will try to bite fingers when a researcher plucks one from a net to take measurements. Gumbert keeps his rabies shots up to date.
Exactly a week before he stood under the bridge — on the same night that a new “Batman” movie was opening in packed theaters — lawyer Joe Childers and his family were returning to their house when an unusual movement in the back yard caught his eye.
“I noticed something flittering around on the ground and I looked and it was a bat,” Childers said.
He had read reports of a rabid bat being found by a dog a week earlier, so he called the health department. After tests, it turned out to be rabid bat No. 2.
It is ironic that the bat ended up in Childers’ yard: In the late 1990s, he filed a suit on behalf of environmental groups that persuaded a federal judge that the Forest Service wasn’t doing enough to protect the Indiana bat, which also is an endangered species.
Logging in the forest was shut down for two years, and has never returned to pre-lawsuit levels.
The discovery of the second rabid bat caused a run on veterinarian’s offices as people rushed to get pets vaccinated, and kindled the fears that humans have long felt toward the animals they associate with witches and vampires.
Health officials advised people to be cautious, but not alarmed. Any bat seen out during the day, or otherwise acting unusual, should be reported immediately, they said.
“We’re not trying to panic the public or give a negative perception of bats. They’re a natural part of the ecosystem,” said Luke Mathis, the health department’s environmental team leader.
Of 37 bats sent to state labs from Lexington this year, Mathis said, only two tested positive for rabies.
And wildlife officials say even those numbers present a skewed view, because only suspect bats were tested. They estimate that rabies in bats is so rare it may be found in only one half of one percent of the population.
No one has a good count of how many bats there are in Kentucky, but the number likely is in the millions. In the last seven years, the state has averaged seven cases a year of bats testing positive for rabies.
What worries people who study bats is white-nose syndrome, a disease that first appeared in New York two years ago. It has since spread to Vermont, Massachusetts and Connecticut, and has killed bats by the tens of thousands, perhaps the hundreds of thousands.
The disease gets its name from the white fungus often found on the noses of sick or dead bats. At first, scientists didn’t know whether the fungus was a cause of the problem, or a symptom.
The consensus now is that something else is making bats sick, and the fungus takes advantage of their weakened state, said Susi Von Oettingen, an endangered species biologist with the New England office of the U.S. Fish and Wildlife Service.
During the winter, when bats are hibernating and living off of stored fat, those with the syndrome appear to be starving. Some have burned off their fat and emerged in the snow to hunt for insects that aren’t there.
In the summer months, even while they are feeding, bats infected with the syndrome appear to have injuries on their wings.
Could pesticides be a problem? Are the injuries caused by being out in freezing weather? Is the syndrome somehow related to another unexplained problem that is killing honeybees in some parts of the country?
“We’re not positive of anything at this point,” Von Oettingen said.
There’s a rush on to find a cure before the syndrome spreads farther.
Although many people are creeped out by bats, we need them.
Traci Hemberger, an endangered species biologist who specializes in bats for the Kentucky Department of Fish and Wildlife Resources, points out a bat zipping around in your back yard can consume 600 to 1,000 mosquitoes in an hour. They also are a friend of farmers, eating cut worms, corn borer moths and cucumber beetles.
Gumbert, for his part, worries about trees being defoliated by insects if all the bats are wiped out.
“If bats stop eating bugs, we’re in trouble,” he said.
Bat populations were in decline for a long time. But over the last few decades, humans are learning how to better co-exist with them.
The largest gathering of gray bats in Kentucky, for example, used to be a cave where 200,000 spent the winter. Now there are two caves, each with 200,000 bats.
The Indiana bat also is increasing in number. When Childers asked the same federal judge earlier this year again to stop logging in the Daniel Boone National Forest because white-nose syndrome could be heading this way, he was turned down. The judge said no, and noted the growing populations of the bat.
In some cases, Hemberger said, the change is directly related to humans, who once messed things up and now are trying to make amends.
And there also are signs that people are becoming more accepting of bats.
Though, there still are cases like the one that happened last year at Kentucky’s Carter Caves State Park, where vandals threw rocks at hibernating Indiana bats, killing about 100.
But Hemberger says she has noticed that fewer people who call her about bats in their house are freaked out.
Instead of “Just come and get them out of here, I don’t care how,’“ she might hear “I don’t want them in my house, but I don’t want to hurt them.”
It’s a feeling she understands. “They really are cute,” she said. “When you hold them in your hand, they’re smaller than you think. And they can be beautiful.”
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