COLUMBIA – Within the past two years, hundreds of thousands of dead bats have been found – their small frames absent of body fat, their wings freckled with scars and their noses covered in a white fungus.
That's according to the U.S. Fish and Wildlife Service. A disease referred to as white-nose syndrome is threatening some bat species with extinction. Bat populations that contract the disease have a 90 to 100 percent mortality rate, the Wildlife Service says. Because bats are the primary predator of nighttime flying insects, a significant decline in population could lead to more pests such as mosquitoes and moths.
“This is the largest decline in North American wildlife in a century,” Peter Youngbaer, white-nose syndrome liaison for the National Speleological Society, said. “Not since the passenger pigeon have we seen anything like this.”
Since it was first recognized in the Northeast, the Fish and Wildlife Service and the U.S. Geological Survey, along with nongovernmental organizations, have raised money to help support research into the causes of the disease and how to keep it from spreading. In addition, many public and private cave owners have either closed their caves or required cavers to decontaminate their gear and clothing.
White-nose syndrome is most common in little brown bats. The first case was found in February 2006 by a caver near Albany, N.Y. Since then, the illness has spread to eight surrounding states: New Hampshire, Vermont, Massachusetts, New Jersey, Connecticut, Pennsylvania, West Virginia and Virginia. With the closest affected cave only 500 miles away, biologists and cavers in Missouri expect the disease to spread to the state within the next two years.
In New England, white-nose syndrome has been characterized by instances of bats flying around during the middle of winter in freezing temperatures, a time when they are supposed to be hibernating.
Bill Elliott, cave biologist and gray bat recovery leader for the Missouri Department of Conservation, said this behavior occurs because the illness causes the bats to prematurely lose body fat needed for hibernation, and they are forced outside to look for food.
“If they lose their fat, they can’t make it through the winter,” Elliott said.
According to the National Speleological Service, scientists have identified the fungus that's associated with the disease as a new species. It was labeled Geomyces destructans in May by a group of scientists. It thrives in cold, damp environments, causing it to spread more rapidly during the winter. It grows primarily on the bat's nose, but has also been found on the wings, ears and tail.
“It is not actually proven that the fungus is the cause," Bill Elliott said. "It could be a new health problem with the fungus as a secondary infection.”
There are still many mysteries surrounding the illness. Cave and bat biologists believe white-nose syndrome is spread largely from bat to bat. Though there are no signs that show humans can contract the disease, scientists suspect it may be spread throughout caves on shoes, clothing and gear.
After a summer convention last year, the National Speleological Society created a rapid response fund to help finance research. More than $63,000 has been donated, Youngbaer said, enabling five different research projects over the past year.
The projects were focused on determining why the bats were dying, Youngbaer said, which included studying their fat reserves and whether they were being forced to wake up too early and burn them off.
“The only plausible explanation at this point is that it is this fungus that’s causing it,” Youngbaer said. “People have looked at lots of other things such as parasites, bacterial viruses, and environmental toxins, but there’s just no evidence to support those.”
A nearly identical fungus has been found in Europe, though there have not been any significant bat die-offs in those locations. Scientists believe that the fungus may have somehow been transferred to the U.S. by air or on the clothes and equipment of a caver.
In addition to the rapid response fund, other organizations such as Bat Conservation International and the Center for North American Bat Research and Conservation at Indiana State University are taking private donations for research. These organizations are also working with the U.S. Congress to fund research in 2010.
“Because it landed so quickly, it fell to the private sector to raise money to get some of that research going,” Youngbaer said.
The Senate Committee on Environment and Public Works was scheduled to hold a joint hearing today on “threats to native wildlife species,” and white-nose syndrome was expected to be discussed. The Committee on Natural Resources also held a joint hearing on June 4 devoted solely to research into the syndrome. A letter, signed by 25 federal lawmakers, was sent to the U.S. Department of the Interior requesting more funds to develop research and possibly a cure.
Tony Elliott, Indiana bat species recovery leader and forest bat biologist for the Missouri Department of Conservation, said the most worrisome problem for the public would be the loss of insect control.
“A bat is capable of eating its own weight in insects in a night, so over the summer our state’s thousands of bats eat millions of insects,” he said.
Bats also provide important nutrients needed in caves through their guano, or droppings.
Missouri is home to about 6,400 documented caves and nine different species of bats, including the little brown bat and two endangered species, the gray bat and the Indiana bat. Although white-nose syndrome has yet to reach gray bat territory, which is mainly located in the southern states, almost 25,000 Indiana bats have already died in affected states.
“The Indiana bat population in Missouri is still declining, even without the presence of white-nose syndrome,” Tony Elliott said. “Based on what is being seen in the Northeast and Atlantic regions, it would potentially decimate the population.”
Of the researchers, biologists and cavers who have come in contact with affected bats, there have been no cases of anyone contracting the illness, which has led biologists to believe it does not pose a direct threat to humans.
On April 24, the U.S. Forest Service issued an emergency closure of caves and mines on national forest land in the eastern region, an area that includes the Mark Twain National Forest in Missouri.
“They saw that as one of the actions that could be taken to slow the spread of white nose syndrome,” said Paul Strong, deputy forest supervisor for Mark Twain National Forest. “Some of the spread happens through recreational or organized people who use caves.”
Strong said the closure will be reevaluated after a year unless the regional forester decides to terminate it early.
Although they have not closed their caves, the Missouri Department of Conservation is asking recreational cavers to disinfect their cave gear and to not use any gear used in states with white-nose syndrome.
Bill Elliott said the Missouri Department of Conservation plans to survey the major caves in Missouri this winter. The survey is usually held every other year so as to not disturb bat populations.
This winter was supposed to be an off year, but the survey is still being held so that biologists can look for signs of white-nose syndrome. He said that if the illness spreads, the Missouri Department of Conservation may install more cave gates to keep recreational cavers out of major caves where bats hibernate.
“These are important species, and we need to protect them,” Bill Elliott said.
Not only are bats being threatened, but the possibility of white-nose syndrome spreading to Missouri could mean less area for recreational cavers.
Columbia resident Bob Lerch, a member of the Cave Research Foundation and the Missouri Speleological Survey, has been a caver for about 15 years. He said that the current closures in the Mark Twain National Forest haven’t affected recreational cavers much, since most of the caves in Missouri are on private land.
“We’re real concerned about it as cavers because it could severely limit our access for a long time,” Lerch said. “It’s not just about us getting into the caves, it’s about the bats that may be affected.”
As a member of the two organizations, Lerch works with private landowners who have caves, educating them about white-nose syndrome has become a part of that outreach.
“I don’t think landowners know about it yet, and that’s why we talk to them about it,” Lerch said. “If they have a cave that has a population and we see any evidence of it, we will let them know.”