Wind-farm turbines are killing more bats than previously thought, says United Kingdom study

Bats can confuse wind turbines with trees
(U.S. Geological Survey photo by Paul Cryan)

Wind-energy farms kill more bats than previously thought, says a study by researchers in the United Kingdom, published in Current Biology. Researchers surveyed 46 wind farms in the UK, finding that 97 percent had bat activity—between one to 236 passes per night—and half of the sites had bat casualties, ranging from one to 64 per month from July to October. More than 600,000 bats were killed by wind turbines in 2012 in the U.S., says a study by a researcher at the University of Colorado published in BioScience.

The researchers "found that environmental impact assessments—the main tool used to predict the ecological effects of a new energy development—commonly failed to predict the number of bats that would have fatal collisions with wind turbines’ spinning blades," Brady Dennis reports for The Washington Post. "Even in the few cases where researchers said early assessments accurately predicted the danger to bats, efforts to mitigate those risks often did not succeed."

Researchers "compared their findings from each site to the environmental assessments they were able to access," Dennis writes. "In most cases, the pre-construction assessments had not accurately predicted the risk of bat fatalities. And even where companies had put in place mitigation measures to try to steer bats clear of the turbines, the researchers found that bats were still killed. Researchers say it is uncertain whether the acoustic surveys widely used to estimate bat activity are not precise enough or whether bats’ 'highly variable' activity means they change their patterns too often to predict with accuracy."