George Steinmetz

Tucked into the woods near the

top of Rattlesnake Hill, in eastern Pennsylvania, is a 19th-century iron-ore mine. Heavy steel slats bar the mine's gaping black mouth. Beyond a hinged gate, down a rubble slope, where the entry tunnel opens into a dark chamber, Pennsylvania Game Commission biologist Greg Turner aims the beam of his headlamp upward, illuminating hundreds of bats clinging to the ceiling. Moisture beading on their brown fur glistens as Turner inspects each one, searching for signs of a killer.

During a normal year, an estimated 10,000 bats winter in Durham Mine, one of the state's largest hibernacula. The bars have kept humans out for 16 years, but they are useless against a new and far more sinister threat, a condition known as white-nose syndrome, or WNS. In a mere season or two, WNS can wipe out nearly every bat in a ­colony. Internet forums used by cavers and wildlife conservationists bristle with doomsday proclamations such as this: "Whatever is going on, it is evil, like the black plague. Birds are now ripping the bats apart… like something from the Book of Revelation."

All told, WNS has killed up to 2 million bats from eastern Canada to Tennessee, with no signs of slowing. If it continues, scientists warn, WNS could result in the biggest decimation of a natural population since the extinction of the passenger pigeon. But while the passenger pigeon was only one avian species out of 10,000, collectively, bat species make up 25 percent of the world's total mammal types. Of the 45 North Ame­rican bat species, WNS threatens more than half. The epidemic affects humans too: A single bat can eat up to 600 insects a night. The bats killed by WNS in 2009 left enough insects uneaten this year to fill 693 tractor-trailers; those include pests that will spread disease, destroy crops and require more chemical pesticides to keep them in check.

"It's absolutely dire," Turner says. "I'm seeing bat colonies I've watched grow for the last eight years bite the dust." Another iron mine in Pennsylvania formerly housed 2317 bats. "I went back a year later and found one bat," he says.

Turner has come to Durham Mine to conduct the first-ever field test of a treatment to stop WNS. He's been joined by two other scientists: Northern Kentucky University's Hazel Barton, one of the world's few cave microbiologists, and Bucknell University biologist DeeAnn Reeder, an expert in bat immune systems. All three wear disposable white Tyvek coveralls to reduce the risk of contaminating other sites with the syndrome­—if, that is, they encounter diseased bats. As recently as two months ago, the mine was clean.

Turner's beam passes along the ceiling, and then it stops. Frowning, he reaches up and gently removes a bat with a white snout and speckled-white wings.

"I guess you answered your question about whether the fungus had arrived," Barton says. Turner euthanizes the bat and slides it into a specimen tube for later verification.

One by one, the scientists belly-crawl through a 12-inch gap between rocks left by a ceiling collapse and then make their way to a pair of chambers deep underground where they will set up their experiment. In one chamber, 16 bats will be enclosed with a plant compound; the other will hold 16 bats in a control enclosure. It's October now. In six months, the team will return to find out if it worked.

Hibernating bats are finicky. They've evolved to winter in caves and mines, which have a climate more consistent than any place on earth. They breathe only four times per minute and are sensitive to the slightest fluctuations in temperature and humidity. But in February 2006, a caver in Howes Cave, near Albany, N.Y., witnessed something strange: hibernating bats whose faces were dusted with a white powder. State biologists observed bats behaving erratically, rousing early and venturing out into the cold, where many died. Before long, bats in Vermont, Massachusetts and Connecticut were acting the same way.

At first, scientists assumed the powder-like fungus was only a symptom of an underlying syndrome—a parasite taking advantage of a weakened immune system the way pneumonia afflicts those infected by HIV. By the spring of 2009, David Blehert, a microbiologist with the U.S. Geological Survey's National Wildlife Health Center, had classified the fungus as Geomyces destructans, a previously unknown cousin of a number of harmless species. Barton and others suspect the fungus hitched a ride on muddy spelunking gear to the U.S. from Europe, where bats appear to be resistant to it.

Although it has yet to be proved, the fungus may instead be the root cause of WNS. And rather than killing bats directly, some scientists theorize, it wakes them early from hibernation, causing their body temperature to rise and their metabolism to increase. Many bats starve while searching for insects that won't return until spring.

To stop WNS, logic might follow, kill the fungus. But Barton fears the knee-jerk application of a broad-spectrum fungicide. "Microorganisms are at the bottom of the web of life," she says. "Whip that rug out and the whole ecosystem falls apart." That's precisely what happened in France's Lascaux Cave in the 1960s. To stop microbes from eating away at the 17,000-year-old cave paintings, panicked officials sprayed the cave walls with a disinfectant. "They created a clean slate for invasive species to come in and do 10 times the damage they were doing before," Barton says.

In her lab Barton began searching for a treatment that would kill G. destructans without harming other cave life—a firewall to stop the fast-spreading epidemic. The only other attempt to do so was a lab-based experiment by another scientist that featured terbinafine, a chemical found in athlete's-­foot cream. The test was a flop for many reasons, not least of which was that all the bats died. Barton homed in on a natural antifungal called carvone, produced by the spearmint plant to keep its roots from rotting. Unlike the synthetic drug, which requires direct application, carvone permeates a cave—at least, that's the theory.





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George Steinmetz

George Steinmetz

In April, the scientists hike back up to Durham Mine. They squeeze through the first tight pinch and crab down a talus slope, careful not to send soccer-ball-size rocks tumbling. "Don't touch anything," Barton warns. "Almost everything you see on the ground used to be on the ceiling."

Some 600 feet into the main passage, the team reaches the first enclosure—the control experiment. Because no one has ever attempted to confine hibernating bats for underground drug trials, Turner had to improvise. To create a cage, he stitched together sheets of netting and pinned them to the ceiling with telescoping aluminum poles from a drywall-dust-barrier system. Barton lifts the black netting and starts looking for bats with lime green, lozenge-size data loggers glued to their backs. Every 10 minutes the devices record the bats' body temperatures, which can jump from 40 F during hibernation to 98 F upon arousal. Reeder had attached the data loggers to learn whether the bats were behaving normally.

But the enclosure appears to be empty. Reeder joins the search, and after 15 minutes, they've found only two of the original 16 data loggers, one glued to the back of a live bat and another to an Oreo-size smudge of fur and bones.

As the team advances into a deeper chamber, the fresh scent of Wrigley's gum begins to drown out the earthy odor of microbial growth. Inside the second enclosure, Barton and Reeder inspect a wooden box that holds an inverted bottle of carvone—the source of the minty aroma. That cage, too, is empty. "I had this vision," Barton says wistfully, "of 16 bats alive and well inside the netting, with lots of others on the outside huddled around this place of safety." Barton and Reeder collapse the enclosure, and Turner heads farther into the mine to search for the escaped bats, at one point descending a 20-foot ledge using a climbing rope and cable ladder. He sees hundreds of bats, but none with data loggers. WNS has infected roughly 50 percent.

Mud-caked and dispirited, the scientists emerge from the mine and head back down Rattlesnake Hill. At the bottom, as they huddle on the highway shoulder peeling off gear, a rusty Ford pickup rumbles to a stop. The driver leans forward: "Were you guys up at the mine checking on the bats?"

"Yeah," Turner replies.

"How are they?"

"Half of them are dying," Turner says, "which is actually pretty good."

Failure is a routine part of science, but the relentless sweep of white-nose syndrome makes today's disappointment especially painful. Still, even before the three have sealed their contaminated gear in oversize Tupperware bins, they've begun plotting another drug trial. Turner and Reeder agree to haul lumber and plastic netting into the mine to build escape-proof cages, and Barton vows to bring an arsenal of targeted antifungal compounds. Next spring, they hope, the bats' outlook will be better.

How to Stop the Spread

Cavers may have helped transmit deadly white-nose syndrome (WNS) by transporting fungal spores on their gear or clothing. Here's how to keep it in check.

1. Observe Cave Closures

The U.S. Fish & Wildlife Service advises not to cave in states with confirmed cases of WNS, in adjoining states or during hibernation. More information and a map can be found at fws.gov/white nosesyndrome.

2. Report Unusual Behavior

Warn your state's natural-resource agency if you see bats flying during the day or roosting in sunlight on the outside of structures, especially from December to March, during hibernation.

3. Disinfect Gear

Wash dirt from clothing, footwear and gear using Woolite. Then soak for 10 minutes in Lysol Professional All Purpose Cleaner, Formula 409 or a 10 percent solution of household bleach. Rinse well and air-dry.

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