In late July, Lisa Gatens surveyed a colony of 200 little brown bats roosting beneath a bridge near Eno River State Park in Durham. One in particular took her breath away.
"She was a beast. She was so big and beautiful," recalls Gatens, curator of mammalogy at the N.C. Museum of Natural Sciences. But when she unfurled the bat's wing, it was marred with white scars. "It really shook me up."
Those white scars could indicate the little bat has survived a winter infection of white-nose syndrome, an epidemic infecting cave-hibernating bats in the U.S. from Vermont and New Hampshire south to Virginia, Tennessee and Oklahoma. The disease shows up as a white fungus growing on a bat's nose, muzzle, ears and wings - anywhere non-furred skin is exposed - and it has killed more than 1 million bats in North America since its onset.
The disease was first documented in New York in 2006, and it's now in 13 U.S. states plus Quebec and Ontario. Mortality rates at infected colonies, where several bat species may hibernate together, approach nearly 100 percent.
The disease is creeping up on North Carolina. It is documented in Smyth County, Va., near the northwestern border with North Carolina, as well as in Sullivan and Carter counties in Tennessee - all of which are close to or abut North Carolina. It is also suspected in Blount County, Tenn.
Gabrielle Graeter, a wildlife diversity biologist with the N.C. Wildlife Resources Commission, is on a team that surveyed 25 winter bat hibernation sites in caves and mines in eight Western North Carolina counties earlier this year. They looked for the epidemic from January to early April, but they did not find any diseased bats. Since then, state biologists have documented several summer bats near the Smokies with wing damage that could be attributable to white-nose syndrome, similar to the one Gatens found by the Eno River.
"It's likely that WNS is already affecting bats in some parts of North Carolina," Graeter says. But so far the disease has not been seen in the state. Until the disease is documented in North Carolina, Graeter says, researchers cannot rule out the possibility that it may bypass the state.
"In North Carolina, we may have an advantage in that we don't have the huge limestone caves that are found in many other states," Graeter says. "Not having as many caves or mines with large numbers of bats together may decrease the rate of spread. Likewise, although we presume that bats are the primary mode of spread of white-nose syndrome, North Carolina is not a big destination area for caving, which may also reduce the chances of spread by human cavers."
Other scientists are more pessimistic. Mylea Bayless, a conservation biologist with the nonprofit research and education group Bat Conservation International in Austin, Texas, sees no reason to believe North Carolina will be immune from one of the worst wildlife die-offs in recent history. Bats that summer in North Carolina typically winter farther north, and the northern-wintering bats have been hit hardest.
Bayless says experts are seeing individuals with scarred wings emerge in spring and early summer, but they are not documenting many in late summer or fall - leading to questions of how the scarring may affect a bat's health.
"We know that their wings are used for physiological processes during hibernation, like gas exchange and water balance, so individuals with heavy scarring may be more at risk as they head into their next winter," Bayless says.
Bats that survive a winter infection groom the fungus off, and their wings become splotchy and scarred. In later stages, very frayed wings may look like moth-eaten fabric. Heavy scarring may affect their fitness to the point that they do not reproduce, Bayless says.
Checking on N.C. bats
To survey N.C. hibernation sites, Graeter and her team travel to remote locations. They don a fresh pair of latex gloves for every bat they handle, and they decontaminate their non-disposable gear or place it in double trash bags upon leaving a cave. "We are doing everything we can to minimize the chances that we are spreading white-nose syndrome between sites and between bats," Graeter says. They wear protective Tyvek suits in the caves and soak their boots in a bleach and Lysol solution upon leaving, to kill any Geomyces destructans spores - the fungus thought to cause the disease - they may have picked up.
Inside the caves, the team identifies each bat down to the species level and counts all the bats they find, even documenting which sections of the cave the bats are using. They scour the floors searching for dead or dying bats, scrutinize the entrances looking for clusters of bats, and keep an eye out for odd wintertime behavior - all signs of white-nose syndrome.
Summer surveys
For their summer surveys, Graeter and her colleagues catch bats in mist nets and examine them for wing damage. They also take hair samples and a small tissue sample from their wings. These are sent to Western Michigan University for genetic study by biologist Maarten Vonhof.
This summer, the N.C. Wildlife Resources Commission completed a surveillance and response plan for white-nose syndrome in North Carolina - in cooperation with the Fish and Wildlife Service - which granted the state $21,143. The plan includes an outline of steps to deal with investigating possible outbreaks.
Only hibernating bats are so far affected; bats that roost in trees are not. The affected species have life spans ranging from five to 30 years. These bats reproduce slowly, only one pup per year. These factors will compound their ability to rebound, experts say.
In early August, a research paper published in the journal Science predicted that little brown bats could be locally extinct in the Northeast in 20 years.
Faced with this prospect in North Carolina, Gatens says, "It's hard to not feel emotional about it. We are looking at local extinctions of very common species. It is heart-wrenching."
