As if white-nose syndrome wasn’t enough, the nation’s bats have another problem: wind turbines that are becoming increasingly more common on the American landscape.
For two months, Paul Cryan, a research scientist for the U.S. Geological Survey, set up thermal video surveillance cameras to find out why up to 900,000 bats are killed by windmills each year.
In the end, researchers came away with a simple conclusion: migrating bats seem to think wind turbines are trees.
That’s not good news for agriculture. Bats that eat bugs by the metric ton are worth about $3 billion a year in pest control for U.S. agriculture, according to Cryan.
Bats face a growing problem in Illinois, a state that ranks fourth in the country in the number of wind turbines with 2,195, according to the American Wind Energy Association.
The forest of windmills in Illinois may be confusing the animals, say researchers. “The way bats approach turbines suggests they follow air currents and use their dim-adapted vision to find and closely investigate tall things shaped like trees,” said Marcos Gorresen, a scientist at the University of Hawaii and a co-author for the recently released study.
The need for alternative energy sources may have created an unexpected hazard for bats, said Steven Taylor, the principal investigator for the Illinois Natural History Survey at the University of Illinois at Urbana-Champaign.
“Wind farms are both positive and negative. The energy they produce is a good thing for us but they also pose a real threat to bats and birds,” he said.
“Some bats are attracted to the highest tree in the landscape and, where there are wind farms, turbines can appear as the tallest ‘trees,’” said Taylor.
The wind machines can prove deadly without a collision, he said.
“Bats don’t have to be hit by the blades. A sudden change in air pressure can impact a bat’s internal organs. These are very delicate creatures, some weighing an ounce or less,” Taylor said.
Some of the recommendations made to lower the bat death toll include having wind-turbine operators turn off the blades when the wind is too low to produce energy. They also could stick a pulsing light on the pole or a beeping device to scare off bats.
But even more dangerous than wind machines to many bat colonies is the white-nose syndrome, the disease that’s claimed at least 7 million bats, wiping out about 90 percent of bats in the Northeast, according to a U.S. Fish and Wildlife Service estimate two years ago, and has spread to 25 states and several Canadian provinces.
Taylor has done research on the impact of the disease on bats in Illinois for the past three winters, checking caves and other bat hangouts across the state.
“Not all bats hibernate in caves but each year, we’ve seen the mortality rate increase at several cave sites. This winter we expect the results to be even more grim,” he said.
For hibernating bats that fly back to caves, it’s often to their doom. The fungus that causes white-nose syndrome doesn’t discriminate between little brown bats, big brown bats, Indiana bats and gray bats. The disease attacks them all.
“We know the bat population is in danger,” said Yvonne Strode, director of the Peoria Zoo, noting that the flying mammals perform a real service. “Without bats, the mosquito problem would be horrible.”
A single bat may consume 3,000 insects in one night, added Strode.
At Forest Park Nature Center in Peoria, bats will be part of the Creatures of the Night Hike, a Halloween event for the family Oct. 24, said manager J.D. Russell.
“Bats will be there but it’s hard to spot them,” he said of the hike. “With an owl hike, you can hear them. With bats, it’s a lot more difficult.”
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