Every night in the summer, bats provide an essential service: they eat bugs by the millions. A single bat can eat thousands of insects in one night. While most people seldom see bats and sometimes fear them, bats are truly the “birds of the night” and play a role as essential to healthy ecosystems as the insect-eating songbirds we see during the day.

But in the Northeast United States, something terrible is happening to them.

In the winter of 2007, scientists in New York documented a mysterious ailment in bats hibernating in caves and abandoned mines near Albany. The obvious physical manifestation of the illness was a fuzzy white ring around the dying bats’ noses. Biologists thus dubbed the unknown affliction “white-nose syndrome.”

The white fuzz is a type of mold, called fusarium, that normally affects plants, not animals. Anyone who grows tomatoes knows about fusarium mold, but scientists aren’t sure that the mold is the primary cause of death. The bats appear to be starving. Before they die, the animals behave oddly, in ways not seen before.

Bats have been seen in Vermont and western Massachusetts — in the dead of winter and in broad daylight — outside of the protective warmth of the caves. The bats appear to be looking for food and have been observed trying to drink the snow. Mortality rates where white-nose syndrome has been documented can range as high as 90 percent.

What was a localized observation by scientists in upstate New York in 2007 is now recognized as an unprecedented threat to bats, occurring in caves and abandoned mines in three states: New York, Vermont, and Massachusetts. Bat species known to be affected by white-nose syndrome, thus far, are little brown bats, northern long-eared bats, eastern pipistrelles, small-footed bats, and federally listed endangered Indiana bats.

It is not known whether the syndrome is an infectious disease, the result of a toxin in the environment, or due to some other cause. What seems clear is that hundreds of thousands of bats in the Northeast are dead or soon will be, and without action, certain populations — and perhaps even certain bat species — may be extirpated from the region for many decades or forever.

The Center wrote a letter to the U.S. Fish and Wildlife Service on January 29, 2008, when news of white-nose syndrome was first getting out to the public. The letter asked the agency to close all caves and abandoned mines to recreational use where the four federally listed endangered bat species in the eastern United States are found. If white-nose syndrome is a contagion transmittable from one cave to another by people, on clothing and equipment — a theory still being considered by scientists — then spread of this affliction could be devastating to bats already endangered.

For example, the global population of the endangered Virginia big-eared bat is less than 10,000. This species cannot afford to lose one individual. White-nose syndrome could spell the end for the Virginia big-eared bat if it were to hit one or more of the species’ hibernating caves in West Virginia.

According to the Fish and Wildlife Service’s records, 10 percent of the total population of Indiana bats winter in New York caves. In the most recent recovery plan for this bat, the Service emphasizes the past decade’s population increase in the northern region of the Indiana bat’s range, including New York, Vermont, and Pennsylvania. It’s now quite possible that nearly the entire population of Indiana bats in these states is gone. The bats are in a more precarious position than ever before.

In February of 2008, the Center petitioned the Fish and Wildlife Service, the National Park Service, the Forest Service, the Secretary of the Army, the Corps of Engineers, the Tennessee Valley Authority, and the Federal Highway Administration to re-evaluate federal projects where any endangered bat in the East might be harmed in light of the threat of white-nose syndrome. These federal agencies oversee highways, dams, and logging in bat habitat. In April, as bats continued to die with no new protections on the horizon, we filed a notice of intent to sue the agencies.

We're working to ensure that the federal agencies who manage the habitat where these endangered bats live proceed with caution in light of this threat we know so little about. We're also making sure we inform Congress that the Fish and Wildlife Service needs a sufficient amount of funding to study the causes of this syndrome.

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Photo courtesy of New York Department of Environmental Conservation