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« on: 07-Apr-10, 07:59:51 AM » |
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ROCKAWAY TWP. — White-nose syndrome has claimed 90 percent of the bats that hibernate in Hibernia Mine, New Jersey's largest hibernaculum, according to a state Department of Environmental Protection official.
Scientists counted just 1,753 bats in the mine during a Feb. 14 visit, a dramatic drop from the more than 27,000 that typically spend their winter there, said Mick Valent, principal zoologist with the state's Endangered and Non-game Species Program.
"We hoped we wouldn't see that, but it's not entirely surprising,'' said Valent, who has been documenting the decline in the state's bat population since white nose syndrome first appeared here in 2008. "It's a good indication of what's happening there and elsewhere.''
The culprit is the cold-loving fungus Geomyces destructans, known as white nose syndrome for the fuzzy powder that grows on the muzzles and skin of stricken bats. The fungus, which is believed to be passed bat to bat, causes the winged creatures to lose stored body fat, forcing them outside their caves early in search of food, well before it is warm enough for insects to be found.
But while the decline is cause for concern, Valent said he was encouraged by a visit in March that revealed more healthy looking bats compared to those seen the previous month.
"They appeared to be in better condition, clean, and their wing membrane remained elastic,'' Valent said. "It was an unusual observation, and one we cannot explain. Last year, we saw worsening conditions, and in April, there were thousands dead.''
Some infected bats have been known to shake the fungus and rebound, but scientists don't yet know why, said David Blehert, a microbiologist with the Wisconsin-based National Wildlife Health Center studying the fungus.
"Research into origins of the fungus are ongoing, but we don't have any silver bullets for managing this problem yet,'' Blehert said. "What we do know is the disease continues to significantly impact hibernating bats across the East coast, and that has a huge ecological impact, one that we don't fully understand.
Some 23 of the United States' 45 bat species are susceptible because they hibernate, Blehert said. The insect-eating mammals consume agricultural and forest pests including moths and beetles, as well as mosquitoes, so bat population declines could lead to a rise in pesticide use and have indirect human health implications.
White-nose syndrome has been linked to more than two million bat deaths spanning 11 states on the East coast, from New Hampshire to Virginia. Scientists last month confirmed it has spread westward into Tennessee through the Appalachian Mountains and into Ontario, Canada through the Great Lakes, Blehert said.
Statewide, it has affected six species of hibernating bats: little brown, northern long-eared, Indiana, eastern pipistrelle, big brown and small-footed. The former four species hibernate in the Hibernia Mine, Valent said. In the spring, the bats seek out forests and wooded wetland areas where they raise their young under the loose bark of trees such as the shagbark hickory or dead or dying elms, oaks, maples and sycamores, across a range that can be more than 100 miles away.
Valent said his team of scientists is researching a technique to help biologists detect the fungus in bats before it is visible to humans. The department is also proposing a program that would take infected bats from hibernation to a center where they would be nursed back to health and reintroduced to a controlled site.
"Our research is promising,'' Valent said. "We need better monitoring of bats. It's difficult to track them from year to year.''
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