Thursday, March 18, 2010

Bat Populations Plummet

In February 2006 a caver photographing hibernating bats in Howe Caverns near Albany noticed some bats with an unusual white substance on their muzzles. The following January New York Department of Environmental Conservation (DEC) biologists documented more bats with white noses, bats behaving erratically, and numbers of dead bats. Since then NY DEC biologists have been monitoring more than 30 winter bat “hibernacula” in New York’s caves and mines. Over the past three years 93% of the bats in the Northeast, afflicted with what is known as “white-nosed syndrome,” have died. According to the US Fish and Wildlife Service, more than a million bats have perished from New Hampshire to Virginia in the past four years!
Nine species of bats occur in Adirondacks. These are species are all insectivorous, consuming one-quarter to one-half of their body weight in flying insects daily in order to survive. In the winter months when flying insects are not available, three of our bat species migrate to warmer climes. The other six species accumulate fat reserves in the fall and then winter in caves and mines in the area where cool but not freezing temperatures permit them to enter a state of hibernation and reduce their energy needs. The fungus known as white-nose syndrome (WNS) apparently causes the bats to awake prematurely from hibernation with substantially depleted fat reserves. Last March, for example, thousands of bats were observed flying and dying near Chapel Pond weeks before there were any flying insects to eat, and more dying bats are being seen flying there this month – long before adequate food is available (see http://www.adirondackalmanack.com/2009/04/bats-flying-and-dying-in-broad-daylight.html). A long-time summer colony of more than 200 Little Brown Myotis under our Lake Placid roof was reduced by last summer to just two bats.

Not all of our hibernating species have been equally affected. Little Brown Myotis (Myotis lucifugus), which as recently as four years ago comprised 85% of our bats, have been especially hard hit along with Northern (Long-eared) Myotis and Eastern Pipistrelles. These bats are now among the rarest bats in New York. The largest known hibernating bat colony in the Northeast, a mine north of Albany protected by The Nature Conservancy, has lost 99% of its bats over the past three years as the hibernating population has gone from more than 200,000 individuals to less than 2,000 bats. Especially troubling is the loss of Northern Myotis (image to the right) , whose total range-wide population had been estimated, before WNS, to be as low as 10,000 individuals.

In addition, 60% of the known world-wide population of Small-footed Myotis (Myotis leibii), pictured here, occur in the winter in just two mines in New York, the largest of those in Essex County. White-nose syndrome was first detected in this species last winter, and substantial losses of this species in the Adirondacks would be would be potentially devastating for the species.

Federal, state, and academic researchers are working hard to find solutions (e.g., experimental applications of fungicides to caves), but at the moment the future for bats in the Northeast and potentially across much of the country appears uncertain at best. According to DEC biologist Al Hicks, the identical fungus has long occurred in Europe, and may have hitchhiked on a European visitor to the commercial tourist cave near Albany where the fungus was first detected in this country four years ago. Wintering bat populations in Europe are much smaller than North American populations, perhaps, Al speculates, because of long-term suppression of populations there by the fungus.

Given the very slow reproductive rate of bats, just one young per year in the case of most of our bats, we may not see any substantial recovery in our bat populations for many decades at best.

For more on white-nose syndrome, see the USFWS web site at http://www.fws.gov/northeast/white_nose.html. Additional images of infected and apparently healthy bats may be viewed at http://www.masterimages.org/Mammals/Bats/White-nose%20Syndrome/index.html and under Bats at http://www.masterimages.org/mammals.html.


Larry Master

Larry Master lives in Keene and has been photographing wildlife and natural history subjects for more than 60 years. After receiving a PhD at the University of Michigan, Larry spent 20 years with The Nature Conservancy and 6 years with NatureServe, most of that time as the organization’s Chief Zoologist. He oversaw the development of TNC’s and NatureServe’s central zoological databases, and also served on the EPA’s Science Advisory Board. Larry currently serves on the boards of NatureServe, the Ausable River Association, the Adirondack Explorer, the Northern Forest Atlas Foundation, Northern New York Audubon, and the Adirondack Council, as well as on science advisory groups for the Wildlife Conservation Society’s Adirondack Program, the Biodiversity Research Institute’s Adirondack Center for Loon Conservation, the Vermont Center for Ecostudies, and Living with Wolves.




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