As bat disease continues its deadly march, study finds it’s killed more than 90 percent of three species

As bat disease continues its deadly march, study finds it’s killed more than 90 percent of three species
A tri-colored bat with the fungus that causes white-nose syndrome on its muzzle. (Source: Virginia Department of Wildlife Resources)

Virginia is one of many states hard hit by a fungal disease known as white-nose syndrome, which according to a study published Tuesday has killed more than 90 percent of northern long-eared, little brown and tri-colored bats in the U.S. over the past decade.

“Virginia populations have suffered really severe impacts from white-nose syndrome, so there are unfortunately just not that many bats left,” said Virginia Tech infectious disease ecologist Kate Langwig, who has studied the disease extensively.

Because of the characteristic way it appears, a white-nose syndrome first appeared in the U.S. near Albany in 2007 and by 2009 had spread to Virginia, traveling southward through the Appalachian region. The fungus that causes the disease (Pseudogymnoascus destructans) typically infects bats during their winter hibernation in caves or mines and can survive more than 10 years in the environment.

Since its emergence, millions of bats have died. The disease has been so deadly the U.S. Fish and Wildlife Service is reviewing whether little brown bats and tri-colored bats should be classified as endangered.

On Tuesday, a new study funded by the U.S. Fish and Wildlife Service and published in “Conservation Biologycombined data from 27 U.S. states and two Canadian provinces to produce one of the clearest pictures yet of the disease’s toll on five bat species.

Among its findings: White-nose syndrome has impacted three of those species — the northern long-eared, little brown and tri-colored bats — with “extreme severity.” And it has spread far and wide. Researchers have found the disease present in anywhere from about a third of the little brown and big brown bats’ ranges to a staggering 93 percent of the Indiana bat’s range.

“Declines were generally least variable and most severe in the Northeast and least severe in the Southeast,” the authors concluded. (Virginia in this study was classified as a northeast state.)

That comes as no surprise to Virginia researchers. Since white-nose syndrome appeared in the commonwealth in 2009, scientists with the Department of Wildlife Resources and Conservation and Recreation have been tracking precipitous declines in bat populations along the state’s western flank.

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