A mysterious ailment, discovered in New York last year and spreading ever since, has killed thousands of bats in several Northeast states.
Hoping to keep the phenomenon, dubbed white nose syndrome, from spreading to Maryland, wildlife officials here are taking no chances.
They're asking everyone who explores caves to protect themselves - and any bats they encounter - by following new federal guidelines that recommend thoroughly washing any equipment they use in caves.
Even if the ailment doesn't reach Maryland, scientists say, a decline in the number of migrating bats from other states could mean a summer with more insect pests here.
Named for the fungus that often appears on an afflicted bat's nose, white nose syndrome killed an estimated 11,000 bats last year in New York state. Since then, it has spread to Vermont, Connecticut and Massachusetts and has been detected in the hibernation sites of up to 500,000 bats. It has shown an ability to kill up to 90 percent of the bats in places where it turns up.
"Every biologist on the East Coast is worried about this," said Leslie Sturges, a naturalist at the Locust Grove Nature Center in Bethesda and a licensed bat rehabilitator.
Bats are the planet's only flying mammals - and many of them eat nearly their weight in mosquitoes and other insects each night. Reducing their numbers would mean more backyard pests and probably an increased use of pesticides, experts say.
"We completely underestimate their ecological role," said Margareta Kalka, an ecologist at the Smithsonian Tropical Research Institute.
A few years ago, she used infrared cameras to videotape bats in Panama and found that they consume up to 84 percent of their body weight in insects each night. Maryland's bats probably have the same voracious appetites, Kalka said.
In the Northeast, bats spend winters hibernating in caves, mines and other sheltered areas. Some migrate each spring, while other bats stay put year-round, said Dana Limpert, a state Department of Natural Resources ecologist.
They usually become active about this time of year, as temperatures climb above 40 degrees, she said.
But white nose syndrome prompts bats to leave their winter caves and shelters before the end of their hibernation season and begin hunting for food that is still scarce - and without any fat reserves to tide them over, experts say.
"They appear to be dying of starvation, and when you feed them, they seem to recover," said Merlin Tuttle, founder of Texas-based Bat Conservation International, a nonprofit that funds bat research.
Tuttle considers the condition the gravest threat to bats in the 40 years he has studied them. He is trying to organize a national scientific conference in June so experts can share what they know and come up with ways to address it.
"This could become a major national issue," he said.
White nose syndrome has been detected in the little brown bat, the eastern pipistrelle and the northern long-eared - all species common in Maryland, according to Limpert. The endangered Indiana bat also is affected, but she said that species is extremely rare here.
"It's just really puzzling and troubling," Limpert said.
There is nothing known to stop the condition's spread, and anyone venturing outdoors this spring could see its effects because many bats here each summer have migrated from winter hibernating spots up to 200 miles away, experts say.
If bats are dying elsewhere, there will be fewer to migrate into Maryland and devour the insects that trouble area gardeners and farmers.
Most bats also produce only one offspring a year, so it will take a long time for populations to recover from massive die-offs.
"These die-offs could have consequences down the road we're not anticipating," said Kimberly Williams-Guillen, an ecologist at the University of Michigan.
In studies published Friday in the journal Science, she and Kalka found that bats and birds eat comparable numbers of insects.
Kalka's work focused on bats that feed on insects in trees in the understory of a tropical forest in Panama. Williams-Guillen examined the effects of bats on insects on coffee plants in Mexico.
In Maryland, the DNR has been conducting annual surveys for years to track the bat population in caves and mines in Western Maryland. This year's count turned up no evidence of white nose syndrome. But wildlife officials remain concerned. "It is in the back of our minds," said Dan Feller, the DNR naturalist who conducts the survey.
Wildlife officials in several states, including New York, New Jersey and Vermont, are asking spelunkers to stay out of caves where bats roost while scientists research the condition.
Maryland officials say that so far, it hasn't been necessary to ask enthusiasts to stop exploring caves because white nose syndrome hasn't shown up here and access to most of the important winter resting places for bats, known as hibernacula, is already restricted.
"A lot of our most important hibernacula are gated, so the public can't get in anyway," Limpert said.
Scientists with Cornell University and the U.S. Fish and Wildlife Service are analyzing bat remains and affected habitats in the hunt for a cause. But they have yet to figure out how the ailment is transmitted, whether the powdery fungus is a just a symptom or if the deaths are rooted in some type of virus, bacteria, fungus, pesticide or other environmental element.
"Right now, we have no answers," said Diana Weaver, a spokeswoman for the Fish and Wildlife Service in Hadley, Mass.
Among the unanswered questions is whether people can spread the condition.
Jennifer Neemann, a psychologist who is president of the Baltimore Grotto, a group of area cavers, said that they make a point of not disturbing bats. "The philosophy's always been leaving nothing but footprints and take nothing but pictures," she said.
Cavers are concerned because white nose syndrome is prompting cave closings in other states and, as it spreads, it could prompt more. Many of the best caves are on private lands in remote areas, where access is permitted only because of good relationships developed over many years with landowners, she said.
"We don't mind if there are temporary closures of caves, it's the permanent closures that worry us," Neemann said.
Members of organized caving groups will comply with those requests, Neemann said.
"Real cavers are the ones who are the most concerned about bats."
Anyone who sees an injured bat is asked to call the DNR hot line at 877-463-6497. Additional in- formation on white nose syn- drome can be found at www.fws. gov/northeast/white_nose.html.