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Extinction Countdown

Extinction Countdown

News and research about endangered species from around the world

Struck out: Fatal fungus could kill off U.S. Northeast's little brown bats in 20 years

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I recently came home from a two-week workshop in remote Vermont, where I was pleased to hear of my fellow students' encounters there with bats. Several of the animals kept sneaking into one of the local hotels, and one curled up in a classmate's hair for a few minutes' nap.

Although most people (including the guy with the bat-attracting hair) are scared of these flying mammals, I saw the silver lining in these stories. As we have previously reported, 95 percent of Vermont's bats have been killed by the deadly fungal infection known as white-nose syndrome (WNS), but at least the bats in that one small town are doing well.

That's not the case in New York State, where WNS was first observed in 2006. According to a study published August 6 in Science, WNS will wipe out the little brown bat (Myotis lucifugus) there, if not the entire northeastern U.S., within 16 to 20 years.

Ecologist Thomas Kunz of Boston University (B.U.) and a team of researchers started out by calculating the mortality rate of little brown bats in caves where WNS occurs. On average, 73 percent of the bats died. With this annual death rate representing 45 percent of the entire local M. lucifugus population, Kunz and his team calculated a 99 percent probability of regional extinction in less than two decades.

WNS hasn't spread throughout the country, however, so the species remains safe—for now—in many of its other habitats.

Meanwhile, because bats play a major role in insect control (yummy), a rise in insect populations (due to a decline in bats) could harm crops or increase the spread of disease.

"Bats are important insect predators," the report's lead author, B.U. postdoctoral researcher Winifred Frick, told WNBC-TV. "An individual little brown bat will eat its body weight in insects each night."

The research focused on the little brown bat, which remains one of the U.S.'s most common bat species. WNS has been observed in eight other bat species nationwide.

Frick and the other researchers say one way to possibly slow the spread of the fungus is for people to build bat houses in their backyards, giving the mammals a safe place to reproduce in the summer. If you're not afraid of bats, and you live in the Northeast, some at-risk bats could thank you for this simple conservation action—one way could be with a reduced mosquito population in your neighborhood.

About that fear of bats: Another study, in the same issue of Science, looked at the perceived danger that bats can transmit rabies and other diseases to humans and surmises that the threat is not as great as it seems. Whereas bats can and do infect humans and other species, the likelihood of transmission is higher if the species share an evolutionary history. In other words, bats are more of a danger to other bats than they are to humans. The researchers sequenced genetic segments from 372 rabies viruses over a 10-year period, tracked the viruses' lineage, and concluded that only one out of every 73 rabies transmissions from bats jumped species.

Photo: Bat with white-nose syndrome, courtesy of the U.S. Fish and Wildlife Service

The views expressed are those of the author and are not necessarily those of Scientific American.

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