Scientists Pin Down Cause of Disease Decimating Bat Populations in the Northeast
European Bats Seem Immune to Fungus Causing White Nose Syndrome in US Bats
The catastrophic decline of northeastern bat populations has been attributed to a fungus known as Geomyces destructans, according to a recent study published in the journal Nature. Known as White-nose syndrome, the disease causes lesions on the bats’ skin and a white growth on their muzzles. Since its discovery in a cave near Albany in 2006, it has spread to sixteen states and four Canadian provinces wiping out more than a million bats. The US Fish and Wildlife Service has called it “the worst wildlife health crisis in memory.”
Photo by Jonathan Mays, Wildlife Biologist, Maine Department of Inland Fisheries and Wildlife
Indeed the disease has so devastated bat populations that some species are in danger of extinction. Nowhere has the impact been more acute than the Adirondack Park in northern New York where the population of little brown bats—once the most common bat in the region—has plummeted 90 percent.
“Losing northern bats altogether from New York in the foreseeable future is a very real possibility,” Carl Herzog, a wildlife biologist in charge of bat conservation and management for the state Department of Environmental Conservation, told the Adirondack Explorer earlier this year.
All told northern bats have declined 98 percent and Indiana bats, an endangered species, are down 60 percent.
Biologist Jeremy Coleman of the US Fish and Wildlife Service, one of the five authors of the study, said that the disease is continuing to spread, though there is evidence that it has stabilized in some colonies. According to the study the disease can be passed from infected bats to healthy bats through direct contact. (Coleman’s co-authors included three scientists from the US Geological Survey: microbiologist David Blehert, wildlife pathologist Carol Meteyer, and wildlife disease specialist Anne Ballmann. The fifth researcher was Justin Boyles of the University of Tennessee.)
Scientists had initially suspected that Geomyces destructans was the cause of white-nose syndrome, and now the new study confirms it. Researchers at the National Wildlife Health Center in Wisconsin found that healthy bats exposed to the fungus developed lesions and other symptoms associated with the disease. Before the study, some experts speculated that the fungus was itself a symptom, not a cause, of illness.
The researchers say little can be done to control the spread of white-nose syndrome. One possibility is manipulating the habitats of caves to make them less hospitable to the fungus. Another option is extending endangered-species protection to little brown, northern, and eastern small-footed bats. But even this may not be enough. “Endangered species protection is not going to give us much in the way of tools to address the biggest threat to these bats, that being the disease itself,” Herzog told the Explorer.
Another question researchers looked at is why the same fungus, which has been found in Europe, has not decimated bat populations there. It’s believed that the fungus may have been inadvertently carried to the United States by a human and introduced to a commercial cave, visited by tens of thousands of tourists every year, in Schoharie County, whence it spread to bat hibernacula.
Bats in Europe may have co-evolved with the fungus building up a resistance to it. It was first reported there in the 1980s.
Phil Brown is editor of the Adirondack Explorer, a bi-monthly newspaper about New York’s Adirondack Park.