For two months, Cryan, a research scientist for the U.S. Geological Survey, led a team that watched the behaviors of migrating tree bats near wind turbines. They set up thermal video surveillance cameras to study them night after night in an attempt to discern why up to 900,000 bats are killed by windmills each year.And bats don't even seem to need to be hit by the turbine blades to be killed. Just being struck by the pressure waves nearby is enough to burst blood vessels in the their lungs and cause them to drown in their own blood.
In the end, they came away with a simple conclusion. Migrating bats that are vision-challenged seem to think wind turbines are trees.
“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.
Long-distance migrating bats, such as the hoary bat, tend to socialize and roost in trees, as opposed to hibernating bats that fly short distances to group in caves. For migrating bats, it seemed to hardly matter that wind from the turbines could toss their little bodies. They fearlessly dived toward the spinning blades of three research wind turbines for various reasons.
If wind turbines weren't a preferred method of power generation by the environmental movement, they would be making far more of a fuss about these deaths.
Is this the end of wind power? No, but it should call into question how wind power projects are sited. I suspect that good wind power sites are also on bird and migration routes because animals have evolved to take advantage of favorable winds in migration. Wind power proponents will either need to find a way to discourage the animals from approaching the spinning turbines, or site the turbines in less favorable locations.
More dead bats is bad news, particularly at this time of year. Around the end of the month, hibernating bats will start flocking back to caverns, where a lethal disease called white-nose syndrome lurks.
The disease will almost certainly kill tens of thousands of them, as it has every year since it was first detected in New York in 2006. The disease has 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.
The one-two punch of wind turbines and white-nose syndrome is an ecological disaster that hits farmers in the wallet, said Cryan, the study’s lead author. Bats that eat bugs by the metric ton are worth about $3 billion a year in pest control for U.S. agriculture, according to a separate report that Cryan also helped write in 2011.