Mysterious Bat-Killing Disease Found In 2 Va. Caves
First, the frogs began disappearing, with as many as 122 species becoming extinct worldwide since 1980. Then honeybee colonies began to collapse. Scientists fear that bats might be next.
For the past three years, biologists in Virginia have been nervously watching a strange die-off of bats in the Northeast as a mysterious fungus spread rapidly through hibernating bat colonies, leaving caves that once served as safe havens for the hibernating creatures carpeted with the tiny, emaciated carcasses of an estimated 1 million dead bats.
Biologists here were hoping that the fungus would somehow be contained or would burn itself out. Instead, they were shocked last week when researchers confirmed the presence of the fungus, dubbed white nose syndrome for the ring of white fungus that collects on bats' muzzles and wings, in two caves in the state: Breathing Cave in Bath County and Clover Hollow in Giles County, hundreds of miles from the other known infected caves.
"We thought we'd have more time to prepare," said Rick Reynolds, a wildlife biologist with the Virginia Department of Game and Inland Fisheries. But it wouldn't have mattered. "Unfortunately, no one knows what to do about it."
What is known is this: As many as 90 to 100 percent of the bats in infected colonies have died within a year of finding the fungus. And with its spread this far south, there's no reason to think it will stop. Scientists are beginning to whisper the unthinkable: complete annihilation of some species.
Just south of the infected Virginia caves, in Kentucky, Tennessee and northern Alabama, gather some of the largest populations of hibernating bats in the world. And these bats have been tracked flying hundreds of miles from their home caves. They could potentially come into contact with and infect or be infected by any number of other species of bats and the as yet incurable disease could be unstoppable.
"If this continues to spread, we are talking about extinctions," said Thomas Kunz, an ecologist and bat expert at Boston University. "I've studied bats for 44 years. This is unprecedented in my lifetime. It's not alarmist. These are just the facts."
Bats, like the disappearing honeybees and frogs, play a critical role in the delicate balance of nature. A single bat will eat 50 to 100 percent of its body weight in insects in a single night. Kunz conservatively calculates that the million bats that have died would have consumed about 694 tons of insects in one year: the equivalent weight of about 11 Abrams M1 tanks.
"You take these bats away, there are a lot of unknowns," Kunz said. "What are these insects going to do that aren't being eaten? They can cause serious damage to crops, gardens and forests, further upsetting both the natural and human-altered ecosystems."
In one study of eight Texas counties, Kunz said, researchers found that if bats disappeared, farmers would have to spend as much as $1.2 million more on pesticides each year. That means more-expensive food, more chemicals in the food supply and the environment, and who knows what other cascading effects on the animals that depend on bats as a source of food or their guano for nutrition. "Eventually, there's a threshold that's going to be reached," Kunz said. "That's not going to recover."
White nose syndrome does not appear to affect humans. That's a blessing and a curse, Kunz said. "There's been little attention and little sense of urgency about this," he said. "Most of us are doing this research on a shoestring."
The fungus appears to be similar to a cold-loving fungus found in caves in Europe. Hibernating bats there, although their populations are far smaller than those in the United States, have shown signs of infection, but none have died.
Did recreational cavers bring the fungus from Europe to the United States? Did spores travel in the wind? Has an always-present fungus been "activated" by something? "I don't think we can rule anything out," said David Blehert, a microbiologist with the U.S. Geological Survey who is researching the disease. "We just don't know."
Because the fungus appears to have leapfrogged this year from caves in the Northeast to Virginia and West Virginia, in caves better known for their popularity among recreational cavers than for big bat populations, the U.S. Fish and Wildlife Service recently issued an advisory closing all caves in 17 states adjacent to the outbreak. No one knows how the disease is spreading -- whether bats are infecting other bats or humans are tracking the fungus into caves on their shoes, scientific survey gear or caving equipment, or some combination of the two. But officials say they want to err on the side of caution. "We're under no delusions that this is going to stop the spread of the disease," said Diana Weaver, a spokeswoman for the Fish and Wildlife Service. "We're just hoping to slow it down enough for science to catch up and find some answers."
In Virginia, site of the most recent outbreak, wildlife biologist Rick Reynolds raced to a school in Cumberland County one morning last week. He'd gotten a call that a bat was flying about in the cold in broad daylight. That was a bad sign. Healthy cave bats are nocturnal and go out only at night during warmer months. They spend the winter hibernating deep inside caves, crevices or old mines. They hang upside down on cave walls in massive clusters, drop their body temperatures, which usually run about 100 degrees, to match the cave's often freezing temperature and fall into a motionless sleep called torpor.
The bat had white spots on its nose and wings. Reynolds's heart sank. He brought the bat back to his office in Verona, stuck it in a bag and shoved it in the office freezer, next to a calzone. He'll ship it to researchers to test for white nose syndrome. If the bat tests positive, it will mean the disease is on the march south.
Later, an hour away, out in Bath County, in the Allegheny Mountains near the West Virginia line, Reynolds met with Rick Lambert of the Virginia Speleological Survey, who has been volunteering to check some of Virginia's 4,500 caves for the fungus. They donned caving gear that had been exposed to the fungus, crammed on helmets and headlamps, and crawled on their bellies through a narrow passage in Breathing Cave to reach a colony of hibernating little brown bats, one of the six bat species that have been found with the fungus.
Their headlamps drew arcs of light on the limestone walls as they surveyed clusters of bats with white fungus around their noses and along their wings. The fungus is little more than a skin irritant, they explain, much like athlete's foot. Scientists aren't sure how it's killing the bats.
The best hypothesis is that the fungus is somehow disturbing the bats, causing them to wake more often than usual. Each time they wake, they use 60 days of the fat reserves they need to make it through the winter. They might be waking up so often that they use up their fat stores and starve to death. That's why infected bats are seen in the daylight, emaciated and searching for food they won't find in the middle of winter. As the two men whispered, some of the fungus-covered bats stirred. Reynolds shook his head. "Nobody expected anything like this."
The two made their counts and took their leave.
"I'd like to give some advice to the southern states," Reynolds said. To him, the spread of the deadly fungus is only a matter of time. "I just don't know what that would be."
He trudged slowly in darkness, up to his waist in dried leaves, toward the weak daylight breaking through the mouth of the cave.
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