Officials say they probably haven’t gone mad from rabies, something humans should fear. More than likely, it’s another troubling sign: Large groups of bats in the nation’s most popular national park appear to be stricken with white-nose syndrome, a deadly fungus that’s wiping out a variety of bat species up and down the East Coast, a possible extinction event, some biologists say.
“We can’t say 100 percent that it’s white-nose, but it most likely is,” said Bill Stiver, the supervisor of wildlife biologists at the park, which straddles the Tennessee-North Carolina border. He said biologists are likely to confirm it when they venture into the caves in mid-February for a yearly census. “Our gut feeling is the disease is starting to manifest itself in the caves.”
At last count, by the U.S. Fish and Wildlife Service a year ago, between 5 million and 7 million bats were estimated to have died from white-nose since it was first discovered in 2006 in a cave outside Albany, N.Y. That’s enough bats to have eaten 8,000 tons of insects per year, many of which devour food crops. Like bees, bats pollinate plants, and in caves, their guano provides nutrients that sustain life.
At Mammoth Cave National Park in Kentucky last week, there was more bad news. Officials confirmed that a northern long-eared bat from one of the park’s caves was infected, another sign that the disease is spreading to the Southeast.
Last March, the Alabama Department of Conservation and Natural Resources announced its presence in a cave complex in Jackson County, a cradle for millions of endangered gray bats. The fungus has been confirmed through testing in 19 states, and detected without confirmation in two other states, officials said.
Little brown bats have been especially hard hit. A survey of 42 sites in 2010 found that the population fell from 385,000 before the disease to 30,000 at that time, a 90 percent decline. The northern bat’s population was in free fall, going from about 1,700 to 30, a 98 percent plummet.
White-nose, linked to a cold-loving fungus known as Geomyces destructans that strikes during the October to April hibernation, was first detected in the Smoky Mountains caves in 2010 but not on bats, “like having the cold virus but not the cold,” Stiver said. Two years later, officials started seeing the disease on a few bats. Now they fear it is full blown.
At Mammoth Cave National Park, until now thought to be clean, the diseased bat was found in the Long Cave. Instead of closing off the attraction, officials are requiring visitors to wipe their feet on decontamination mats to avoid spreading fungus spores to other areas.
Steven Thomas, leader of the National Park Service regional monitoring program, was poking around in the caves when he made the discovery. “I saw a white spot on a bat,” he said. It was euthanized Jan. 4, and a lab test came back positive.
Federal agencies and a host of nonprofit groups have waged an uphill battle against the fungus, in laboratories studying ways to kill it, and building fake caves so bats can avoid it. But a grim reality is setting in.
The common little brown bat might all but disappear in the East and possibly the Midwest if the fungus continues to spread. They also fear for the northern long-eared bat and the Indiana bat.
A white-nose death is grisly. The fungus hits when the bats’ breathing is low and their tiny heartbeats are at an ebb in hibernation.
Scientists at the U.S. Geological Survey and the National Institutes of Health theorize that the bats die when they awaken from hibernation, and their reactivated immune systems go overboard in an attempt to eliminate the intruding disease, destroying the illness but also tissue bats need to live. Ligaments in the wings of bats appear scorched.
There was positive news in 2011 that a few little brown bats in the Northeast were resisting the disease, hanging on to existence “by a tiny little fingernail,” a Vermont conservationist said. But in the past two years the disease spread south and as far west as Iowa.
Days before Christmas, reports of erratic behavior started coming in to the ranger station at Great Smoky Mountains National Park, which boasts 275 million visitors a year. As a precaution, officials warned visitors to beware of bats because of the risk of rabies. Bat teeth are so small that people might not know they had been bitten.
But Stiver said the behavior is consistent with white-nose, which was most lethal in the Northeast after three years. “And what do you know, it’s been here three years,” Stiver said.
There are 11 species of bats in the 500,000-acre park, representing a fifth of all its mammals. Bats that fly around in the winter are doomed, even when they don’t have white-nose. They use up fat reserves stored for the winter and starve because the bugs they eat are hibernating.
At this point, bats are in a deadly endurance test, Stiver said. Some might develop an immunity to the fungus, as have bats in Europe, from where Geomyces destructans was likely brought, wildlife biologists say.
Otherwise, the observation of Mylea Bayless, conservation programs manager for Bat Conservation International in Austin, might prove correct.
“We’re watching a potential extinction event on the order of what we experienced with bison and passenger pigeons for this group of mammals,” she said.