For bats in the Northeast, fall means swarming time. Bats arrive at cave openings by the hundreds and thousands in preparation for hibernation. But this year, this bat tradition is missing from some caves and old mine shafts. White-nose Syndrome (WNS) has taken a serious toll.
In February 2006 near Albany, N.Y., a caver photographed hibernating bats with an unusual white material on their muzzles. He noticed several dead bats. The following winter more bats were found behaving erratically, others with white noses, and a few hundred dead bats were found in several caves. New York Department of Environmental Conservation biologists documented white-nose syndrome in January 2007.
Hundreds of thousands of hibernating bats have died since. Biologists with state and federal agencies and organizations across the country are still trying to find the answer to this deadly mystery. Bats have been found sick and dying in unprecedented numbers in and around caves and mines from Vermont to Virginia. In some hibernacula, 90 to 100 percent of the bats are dying.
While they are in the hibernacula, affected bats often have white fungus on their muzzles and other parts of their bodies. They may have low body fat. These bats often move to cold parts of the hibernacula, fly during the day and during cold winter weather when the insects they feed upon are not available, and exhibit other strange behavior. During late winter and early spring this year I was contacted by many people wondering why they had seen bats flying during the day with snow still on the ground.
Recently, biologists from the Vermont Fish and Game Department and the US Fish and Wildlife Service conducted their annual fall survey of the Elizabeth Mine in Strafford, VT. In normal years they capture around 900 bats during the survey. Last year they found only 300 bats. This year one juvenile male bat was captured on the first night and just one more two nights later.
Despite the continuing search to find the source of this condition by numerous laboratories and state and federal biologists, the cause of the bat deaths remains unknown. Recent identification of a cold-loving fungus could be a step toward an answer. Although biologists are not sure this is the killer, it is the leading candidate. The current hunch is that perhaps it was introduced accidentally from Europe, but that is just speculation at this point.
This year biologists are conducting an experiment to help understand WNS transmission. Healthy bats from Wisconsin are being sent to Vermont at the end of October. Two sites in VT now have bats excluded from them. The healthy Wisconsin bats will be placed in the mine shafts to hibernate. If these bats contact WNS, the biologists will know it is from the hibernacula and they can then come up with a way to eradicate the fungus from the cave.
One thing is certain, bat populations are in serious trouble and biologists are scrambling to find the answers before it is too late.