It’s a day earlier, and the sun is still young in the morning sky. A group of journalists from the conference has piled onto a bus on our way to Laurel Caverns , the biggest cave system in Pennsylvania. With us are representatives of the U.S. Fish and Wildlife Service, there to tell us about a fungus called Pseudogymnoascus destructans , best known by the name of the often-fatal disease it causes in bats, white-nose syndrome (WNS).
Since the pathogen first turned up in 2006, millions of bats have fallen victim to its deadly embrace. It often collects around their snouts, which is where the disease got its name, but that’s not where the worst damage occurs. “It erodes right through their wing membranes,” Robyn Niver , endangered species biologist with the Service, tells us during the two-hour bus ride from downtown Pittsburgh. “Flight is extremely important for bats, and the fungus affects their basic ability to move around and forage for themselves.”
The easily transmissible fungus also does something to bats’ metabolism, causing the animals to wake up during hibernation more than twice as often as they normally would. This increase in winter activity burns up the bats’ winter reserves of fat, water and electrolytes, leaving the animals hungry, thirsty and confused. “If they go out to forage in the winter, there’s nothing available to them,” Niver says. “They’ll go out on the landscape and just die. Sometimes you’ll see piles of dead bats. Other times they’re just gone.” Caves that once held tens of thousands of bats now, more often than not, now lie nearly empty.
Bat skulls and bones on the floor of Aeolus Cave, a white-nose syndrome site in Vermont. Photo: Ann Froschauer/USFWS
That’s the case in Laurel Canyons. Before the disease turned up, the caves were the winter home of a relatively small population of hibernating bats, about 2,500 animals from four species. Last year, Canyons representative Laura Hall later tells us, they counted just 12 bats.
We knew going into Laurel Canyons for our two-hour underground tour that we weren’t likely to see any of the flying mammals. For one thing, it was still a few weeks before hibernation season. For another, the guides wouldn’t have taken us into the bats’ hibernacula. But still, knowing what we knew, the caves we explored felt eerily silent and empty.
Other Pennsylvania caves must seem even worse. Greg Turner , a mammologist and WNS researcher with the state’s Bureau of Wildlife Management, shared information on bat declines throughout the state. One mine, he tells us, had more than 30,000 bats in 2007. White-nose syndrome arrived just three years later. By 2013 only 155 bats remained. In cave after cave, that pattern has repeated itself.
And Pennsylvania is not alone. White-nose can now be found in 31 states and 5 Canadian provinces and has affected nine bat species, including the endangered gray bat (Myotis grisescens ) and Indiana bat (M. sodalis ). Some populations have fallen 99 percent or more, meaning other species could soon become officially endangered.