Billion Dollar Bats in Danger

Not taking actions to help reduce the national rise in bat mortality could cost the United States billions of dollars.

Bats mean big money for American farmers. Their nightly bug-munching saves U.S. agriculture between $3.7 to $53 billion a year on pesticides and crop losses.

A U.S. Geological Survey study, published in Science, put a dollar sign on the services bats offer free of charge. The study found that bats are high rollers in the game of insect control. But the researchers are worried.

Bats are dying off in unprecedented numbers. A bat-plague, called the white nose syndrome, has wiped out over 70 percent of the bat populations in some of the 16 states and 3 Canadian provinces where it has been found. And the fungal disease is spreading west from New York, where it was discovered, into areas with higher agricultural outputs like the Midwest.

Bats in the Midwest are already getting clobbered by wind turbines. The energy producing turbines cause air pressure changes that damage bat lungs. They also smack the flying mammals out of the sky with their rapidly spinning blades.

"Additionally, because the agricultural value of bats in the Northeast is small compared with other parts of the country, such losses could be even more substantial in the extensive agricultural regions in the Midwest and the Great Plains where wind-energy development is booming and the fungus responsible for white-nose syndrome was recently detected," said Tom Kunz, a professor of ecology at Boston University and co-author of the study in a USGS press release.

The interaction of white nose syndrome and wind turbines are giving the bats a one-two punch, that could result in serious economic consequences within the next five years, if the death rate continues unabated.

For example, an earlier study by Kunz and colleagues estimated that 33,000 to 111,000 bats will die each year by 2020. And that's just in the mountainous region of the Mid-Atlantic Highlands, and only from wind turbines.

"We hope that our analysis gets people thinking more about the value of bats and why their conservation is important," said Gary McCracken, a University of Tennessee professor and co-author of the study in a USGS press release.

"The bottom line is that the natural pest-control services provided by bats save farmers a lot of money," McCracken said.

IMAGE 1: Insect-Eating Brazilian Free-Tailed Bats (Tadarida brasiliensis) in a Texas Evening Sky. (Paul Cryan, USGS)

IMAGE 2: In Pennsylvania, a hibernating little brown bat with white muzzle typical of white-nose syndrome. (Greg Turner, Pennsylvania Game Commission, USGS)

IMAGE 3: A bat killed by collision with a wind turbine on Pag Island, Croatia (Ana Jančar, Wikimedia Commons)