Wildlife biologists Greg Turner and DeeAnn Reeder slip into the sort of coveralls you would expect to see on an infectious disease ward and enter the cold, musty confines of an old Fayette County mine.
With headlamps lighting their rubble-strewn path, they venture deep into a labyrinth of rooms long abandoned except by bats. Here, thousands of Chiroptera hang in torpid clusters, seemingly oblivious to human intruders. When Reeder, a Bucknell University assistant professor, uses a pole topped with duct tape to pluck a bat from a huddling brown mass, the tiny creature begins to arouse and squeak. Reeder records the bat’s body temperature from a dime-size data logger glued to its back, puts the bat into a sack, and hands it to an assistant, who hurries it to a makeshift lab outside the mine. There, Reeder’s graduate students are waiting to draw blood that they hope will yield clues about the animal’s immune competence.
One researcher snips off the bat’s head and collects fluids from its trunk into a vial. She extracts the spleen and other organs and zips them into a baggie, which is then labeled and iced.
It goes on like this with several more bats. Although they appear to be healthy—there’s no telltale fungus around their muzzles or wings, no wasting of wee limbs—the bats may be infected with a deadly disease that is confounding experts all over the world. Known as white-nose syndrome, it is spreading like wildfire through much of the U.S. and making habitat loss, wind farms and other impacts to bat populations pale in comparison.
While the genesis remains a mystery even five years after white-nose was discovered in a cave in upstate New York, the prognosis is ominously clear: unless scientists determine how to combat this plague, one of the world’s most abundant and useful creatures could become extinct, with devastating consequences for the rest of us.
Each night, a female bat eats about 4,500 insects, including mosquitoes, moths and crop-damaging pests, according to Bat Conservation International, an Austin-based nonprofit that is helping fund white-nose research. Accordingly, 1 million of the white-nose infected bats that have died so far would have consumed 700 tons of insects in a year.
In other parts of the globe, bats also pollinate plants. People who can get past unfounded fears about bats sucking humans’ blood and tangling in their hair would find the world’s only flying mammal fascinating, said Reeder, an ecophysiologist. “They’re sophisticated, exquisitely evolved organisms who function in complex social networks and are completely in tune with their natural environment. They’re so tightly balanced… always on the edge, really.”
Bats learn their surroundings by emitting sounds undetectable to humans, said Turner, the Pennsylvania Game Commission’s endangered mammals specialist. “This ultra-sonic, echolocation process enables them to know where every twig is and to find insects as they’re navigating through the forest at 30 miles an hour.”
When Turner nets bats for banding in the woods, it is only because they get lazy, he said. “It takes a lot of energy to scream repeatedly at the top of your lungs, so they cheat. They figure they have a pretty good ‘picture’ of their environment. If they’re thrown a curve and get captured, they’ll never make the same mistake again. They learn well.”
What’s also cool about bats is their unusual reproductive strategy, Turner said. “Females mate and then keep sperm viable for six or seven months during winter hibernation. They’ll fertilize their eggs only after they arouse and leave their cave in spring.”
Females from various hibernacula gather in maternity colonies in barns or in trees where they can nestle under exfoliating bark. They each produce a single pup, which they sometimes carry on their bellies, Turner said. “Where they go, no one knows. But in late July, early August, they can literally disappear off the radar and then suddenly return. By late fall, they head back to their wintering sites.”
These small litters produced only after two or three years make the prospect of a population rebound from white-nose devastation particularly dismal. Of Pennsylvania’s six hibernating species, just two—the state-threatened Small-Footed and federally endangered Indiana bats—are considered rare, although white-nose is changing that. Plans are under way to reclassify hitherto common Little Brown, Big Brown, Northern Long-Eared, and Tri-Colored bats as state-endangered, Turner said. “All of these species are crashing.”
The spiraling loss is taking an emotional toll on scientists who repeatedly face white nose carnage. “It’s been a depressing winter to go into primary field sites where most of the bats are in horrible condition. We’re finding them on the ground and carcasses floating in the water and bats just… gone,” said Reeder. “It’s so sad and tragic.”
Wildlife biologist Nina Fascione, executive director of Bat Conservation International, described white-nose as a “heartbreaking setback” to one of her agency’s critical missions. “We’ve worked 30 years to get the Gray Bat off the federal endangered list. And just when that seemed about to happen, we got news the species tested positive for white-nose fungus. There wasn’t a dry eye in our office that day.”
Scientists have linked white-nose to a cold-loving fungus in Europe that they suspect traveled to the U.S. on the gear of scientists or recreational cavers. Although non-fatal overseas, here it may have spawned the syndrome that, as of March, had cut a deadly swath through 15 Eastern and Midwestern states as well as parts of Canada.
“We compare it to the Europeans bringing smallpox to the New World,” said U.S. Fish and Wildlife Service white-nose spokesperson Ann Froschauer. “The Native Americans had no resistance.” Because people are blamed for big geographic jumps in white-nose transmission, the service is urging cavers to use site-specific gear, and avoid affected regions altogether. While a moratorium on caving is voluntary, Froschauer said cave closures are one preventive strategy.
The caving community, which includes commercial cavern operators and wild cave explorers, is divided in its response, according to Gordon Birkhimer, president of the National Speleological Society, whose members are helping support white-nose research. “The U.S. Parks Service and other federal agencies are gating caves left and right. The show-cave owners are afraid they’ll go out of business. Our organization does not advocate a blanket closing of caves. Our mantra is ‘decontaminate your gear.’ But it’s clear the days of free-caving are over.”
Rich Monty, an Indiana, Pa. caver who chairs the NSS-affiliated Pennsylvania Inner-Earth Grotto, said he avoids known “sensitive” sites and those with large numbers of bats. “Cavers are the first to try to minimize exposure, because we’re the ones spending time in caves. But this disease is bad; it just keeps spreading.”
Scientists believe white-nose is specific to hibernating bats, with no evidence it can affect other species. It is transmitted most during winter, when bats are living on fat reserves and their respiration and heartbeat become very slow. “Spores become airborne in caves, and, of course, bats have climbed over each other to form these big clusters,” said Turner. “Their gregarious nature makes the rate of spread high, and white-nose is so potent it doesn’t take much for 99 percent of a population in a hibernaculum to become infected.”
White-nose bats often are emaciated, fly outside on winter days, and have a powdery growth on their faces and wings. Once thought to be a symptom, the fungus is now suspected as the primary causative agent in the disease. “We know the fungus is digesting live cells, going through the top layer of skin—the most protective and resilient layer—and then eating away at the lower levels of tissue membrane,” Turner said. “This doesn’t mean it’s causing the animals to die. The strongest theory is that it is leading to dehydration. Another is that ‘white-noses’ are arousing twice as frequently in winter, which is severely depleting their fat reserves. When those are off, they need to alter their hibernation patterns and that’s exhausting them.”
Data loggers, such as those glued to select bats in the Fayette Co. mine, are enabling Turner and Reeder to monitor how often hibernating bats are “rebooting.” Other technology monitors ambient temperatures and humidity. This summer, the Turner-Reeder team will attempt to create a micro climate in a bio-secure lab at the University of Georgia in which infected bats can survive. “If we can figure that out,” said Turner, “we may be able to manipulate conditions in mines that would give bats a fighting chance.”
The team is also conducting treatment trials in Pennsylvania mines, where they have placed anti-fungal agents from the roots of common plants in petri dishes. “These agents release a gas we hope will circulate and retard fungus growth in the environment,” Turner said. “Of course, there are a lot of variables, including the impact on other species—mostly invertebrates—that also inhabit mines. We can’t risk harming them.”
Turner and Reeder aren’t banking on a eureka moment from their work, or that of colleagues, which includes exploring the role of pesticides in bats’ habitat and forage. But even with few answers, Turner is pondering species recovery. “My hope is that survivors will aggregate and that healthy bats will reproduce. We can try to help this process along by protecting their winter sites—by putting up gates—and monitoring their colonies.”
If a particular species is verging on extinction, captive-breeding is a possibility, but it is so costly and difficult it would be done as a last resort, said Turner, who admitted the future looks grim. “Even in a best-case scenario, it will take hundreds of years—and multiple human generations—for bats to recover populations.“
“It’s not going to happen our lifetime, or our kids’ lifetime, if at all.”