Risk to bat population found to be greater than thought, bringing risk of rise in insect plagues

Labour’s vision of building up to 7,000 wind turbines by 2020 could bring ecological dangers by killing Britain’s bats, according to a study published yesterday.

Because bats play a vital role in the ecosystem by preying on insects, a reduction in the bat population could mean a dramatic upswing in insect infestations, the researchers warned. Seven of Britain’s 17 native bat species are already rare or endangered.

Far more bats than birds die through collision with turbines, but the new study has found that drops in air pressure around the spinning blades can also be fatal for the flying mammals.

Bat lungs are relatively fragile and surrounded by tiny blood vessels. A sudden drop in the outside air pressure often leads to an over-expansion of their lungs, bursting these blood vessels and killing the bats.

Post-mortem examinations on 188 bats killed at wind turbines on just one night revealed that half had no sign of external injury and had died from internal bleeding.

The leader of the study, Erin Baerwald of the University of Calgary in Canada, said that bats face a far greater threat from the turbines than do birds. “An atmospheric-pressure drop at wind-turbine blades is an undetectable and largely unforeseeable hazard for bats,” he said. “Birds, who have more rigid lungs, survive such drops in air pressure.”

The scientists said that there was no obvious way to cut the pressure drop at turbines without limiting their use.