After nine months of research, biologists have confirmed the presence of a mysterious disease that has killed hundreds of thousands of bats in the northeastern United States.
White nose syndrome, so called for the fungus found around the faces and wings of many afflicted bats, isn't contagious to humans, household pets or other animals. But its sudden appearance, unknown pathology and potential to seriously harm the population of an environmentally vital mammal have scientists concerned.
Previously confirmed in New York, Vermont, Connecticut, Massachusetts and New Jersey, conclusive evidence of white nose syndrome in Pennsylvania was discovered in late December at an old iron mine near Shindle, Mifflin County, according to the Pennsylvania Game Commission, the state agency responsible for wildlife management.
DeeAnn Reeder, a biologist with Bucknell University, and Greg Turner, a biologist with the Game Commission's Wildlife Diversity Section, found the curious fungus during weekly field studies of three known Pennsylvania hibernation caves. The research is part of a multistate effort in Pennsylvania, New York, Vermont, Michigan and Kentucky funded primarily by the U.S. Fish and Wildlife Service.
After weeks with no changes among bats in the Mifflin County mine, on Dec. 20 Reeder and Turner noticed bats waking from hibernation and moving toward the mine's gated entrance -- unusual December behavior. A small amount of white fungus was detected on some. On Dec. 29, about 150 of the mine's 2,200 wintering bats appeared to be affected, Reeder and Turner said. By Jan. 5, about 45 percent of the colony had moved toward the mine's entrance. Dozens of bats suddenly developed the fungus around their muzzles and wing membranes, while others displayed additional symptoms.
Several of the bats were sent to the National Wildlife Health Center in Madison, Wis., which reported last week that preliminary tests were positive for white nose syndrome.
"The visible fungus appears on some, but not all, [afflicted] bats, and a significant percentage of bats in affected hibernacula move closer to the entrance," said Turner. "The bats eventually leave their hibernacula -- often in daylight, which is unnatural."
Most of the prematurely exiting bats die, but some may return to the cavern.
"[We] cannot determine what the bats are searching for, or if they're hunting for anything," said Turner. "Most bats found dead on the landscape have depleted their fat reserves."
The outbreak has impacted recreational caving. Last year, the Pennsylvania Department of Conservation and Natural Resources closed Barton Cave, a popular Fayette County spelunking site, for one year as a precaution. And the National Speleological Society, which owns or manages 13 cave preserves nationwide, has banned spelunkers from four of its sites until more is known. Tytoona Cave Nature Preserve in Blair County was reopened to spelunkers following a precautionary health closure.
The little brown bat has been hardest hit by white nose syndrome, but deaths have been reported among other species including northern myotis, Eastern small-footed myotis, long-eared Eastern pipistrelle and the endangered Indiana bat.
Researchers admit they're in the first stages of understanding the outbreak. While infection seems to spread from bat to bat, they don't know whether the fungus is a cause or symptom of the disorder. Afflicted bats are found emaciated and seem to have starved to death. Most troubling is that the impacted geographic area is expanding. First noticed in bat colonies in New York in 2006, white nose syndrome has spread to some, though not all, hibernacula in Connecticut, Massachusetts, Vermont, New Jersey and now Pennsylvania.
Hardy mammals that have survived for about 50 million years, bats play an important ecological role in the environment. A bat can consume 25 percent of its body weight in flying insects during a night's feeding. In Pennsylvania alone, bats collectively eat tons of insects each night, impacting agriculture and the spread of insect-borne disease, not to mention backyard comfort.
Game Commission biologist Lisa Williams said the sudden appearance and rapid expansion of white nose disease has been frustrating for scientists and wildlife agencies.
Correction/Clarification: (Published Jan. 28, 2009) Tytoona Cave Nature Preserve in Blair County has been reopened to spelunkers following a precautionary health closure. This story as originally published Jan. 27, 2009 reported it was closed to cavers.
John Hayes can be reached at email@example.com or 412-263-1991.