Thursday, October 29, 2009

Bats in eastern U.S. face worst threat ever

Bats in eastern U.S. face worst threat ever

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Just two years ago at Halloween I gave a commentary encouraging people to appreciate bats. There I pointed out that all Illinois bats feed on insects, and that they consume enormous quantities of mosquitoes and agricultural pests. That commentary ended with this rhetorical flourish: “If the thought of living with bats makes you shiver, think of where we’d be without them.”

I didn’t know it at the time, but earlier that year scientists in New York had documented a new disease that could make the nightmare of a world without bats—at least some species--real.

It’s called “White-nose Syndrome,” and in the words of Jean Mengelkoch, a biologist with the Illinois Natural History Survey in Champaign, “It’s the worst thing that’s ever happened to bats.”

White-nose syndrome seems to be caused by a newly described fungus (Geomyces destructans) that grows on the muzzles and bodies of bats that hibernate in caves and mines. It appears the fungus causes affected animals to become active in temperatures too cold for insect-catching, which means they use up the fat stores needed to survive the winter prematurely. [ Photo by Marvin Moriarty/USFWS depicts a little brown bat with white-nose syndrome.]

According to a U.S. Fish and Wildlife Service estimate, some 400,000 bats have already died from White-nose Syndrome, and there is no end to the carnage in sight. What’s even more disturbing than the overall number of bat deaths is the rate of mortality among some afflicted colonies, which can reach 100%. That’s how scientists say, “Sometimes, every single one dies.”

Here it is even more depressing but relevant to remember that bat populations do not rebound well, either, on account of the way they live and reproduce. Many small mammals, such as mice, live short lives—a year or so—but produce multiple litters of multiple young in that time. This reproductive strategy results in populations that bounce back quickly from catastrophic declines. Bats are different. They live long—typically 10-20 years among the species most afflicted by White-nose Syndrome--and they reproduce very slowly, with females giving birth to only a single pup per year. This reproductive strategy is very ineffective for rebuilding a population that crashes.

So far, White-nose Syndrome has spread approximately 450 miles from where it was first documented, and it now affects bats in nine states. The closest cases to Illinois are in Virginia and West Virginia, where it seems to have been transmitted by cavers who were visiting from affected areas in the northeast. Apparently the fungus survives in soil where it can be picked up on clothing and other gear and then taken to new locales.

In an effort to slow the spread of White-nose Syndrome, the eastern region office of the National Forest Service closed all caves and mines on National Forest System land—including those in the Shawnee National Forest--in April of this year.

If there is anything positive to say on the subject of White-nose Syndrome in bats, it can be only that people are responding to the threat with all of the concern it deserves. Scientists from state and federal agencies are working feverishly to understand the causes of and identify remedies for the problem. And cavers, whose recreation is affected by closures, are cooperating with and raising money for efforts to stop the spread of the disease.

See more on White-Nose Syndrome at: