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Wind turbines are killing more bats than ever

A new study has found that wind turbines are causing "unprecedented numbers" of fatalities in tree bats.

The study, conducted by researchers at the U.S. Geological Survey's Fort Collins Center in Colorado and published in PNAS, found that tree bats are more susceptible to wind turbine deaths, because the turbines' wind current resembles the wind currents surrounding tall trees. The bats approach the turbines expecting to find the resources they'd find in trees, such as a place to rest or insects to eat — and end up dying instead.

"These bats have been around for millions of years, but nothing in their history would prepare them to recognize wind turbines," Paul Cryan, a research biologist at the U.S. Geological Survey and author of the study, told The Week.

So, what can we do to reduce the bat fatalities at the turbines? The wind turbines already have flashing red lights, which can help bats distinguish the turbines from trees, but Cryan's study also found that changes in the turbines' operation could reduce bat deaths, too. Most of the bat fatalities the researchers observed occurred when average windspeeds were lower, though more research is needed to determine why this is. Cryan said that fatalities could be reduced by waiting until the wind speed is higher to start the turbines' rotation, so the bats will be able to sense the turbulence and avoid the turbines.

Since adult bats reproduce very slowly, their deaths could have lasting effects on the species' population. "We know that thousands of bats are being found beneath wind turbines each year," Cryan told The Week. "These populations may be doing okay, they may be headed toward extinction, we simply don't know based on the information we have right now."