More than a half-million bats were killed by flying into high-speed wind energy turbines last year, according to new research scheduled for publication next week in the journal BioScience. Previous estimates had said that the clean-energy producing mechanisms were responsible from between 33,000 to 880,000, but a new analysis of dead bats found at wind turbine sites conducted by University of Colorado-Denver researchers places that figure at over 600,000. In a statement, the university calls the discovery “a serious blow to creatures who pollinate crops and help control flying insects,” while study author Dr. Mark Hayes, a research associate in integrated biology, added that “the development and expansion of wind energy facilities is a key threat to bat populations in North America.” “Dead bats are being found underneath wind turbines across North America. The estimate of bat fatalities is probably conservative,” Hayes added. He added that fatality rates were highest in turbines located near the Appalachian Mountains, including those in Buffalo, Tennessee and Mountaineer, West Virginia. Bats are killed by flying into the turbines, which rotate at speeds reaching 179 mph and have blades that can be up to 130 feet long. Hayes believes that the estimates are likely conservative because he used minimum fatality estimates reported by wind facilities, and that the estimated deaths were only recorded during periods of migration. Furthermore, little data was available for facilities located in the Rocky Mountains or the Sierra Nevada region, the study author said. Haynes believes that the actual number of bat fatalities could top 900,000. According to the university, there are 45 known bat species living in the contiguous US, and many of them are important for economic reasons. They help control mosquitoes and other flying insects, as well as pollinate commercial crops, flowers and other types of plans. The hoary bat, the eastern bat and the silver-haired bat are the species most at risk, he said. However, there are ways that turbine operators could help limit the potential harm, he said. For instance, the turbines could be activated to spin at higher wind speeds during the times when bats tend not to fly. “A lot of bats are killed because the turbines move at low wind speeds, which is when most bats fly around. In a recent study in Pennsylvania, researchers adjusted the operating speeds from 10 mph to 18 or 20 mph and decreased fatalities by 40 to 90 percent,” Hayes explained. He also cautions that more bats will die in the future, when use of the clean energy technology becomes more widespread. However, Hayes is quick to point out that he is “not against wind energy. It’s clean, it reduces pollution and it creates jobs.” Despite the negatives, he believes that the bat-death issue is “a problem we can solve.”