Bats are at risk from wind turbines, researchers have found, because the rotating blades produce a change in air pressure that can kill the mammals.

Bats use echo-location to avoid hitting the blades but cannot detect the sharp pressure changes around the turbine.

The scientists say wind farms are more of an issue for bats than for birds.

“An atmospheric pressure drop at wind turbine blades is an undetectable – and potentially unforseeable – hazard for bats, thus partially explaining the large number of bat fatalities at these specific structures,” said Erin Baerwald, who led the research team at the University of Calgary

The idea is that the pressure around a rotating turbine blade is lower than in the surrounding air. A bat flying into the low-pressure zone finds its lungs suddenly expanding, bursting capillaries in the surrounding tissue which then becomes flooded with blood.

Birds, which have more rigid and robust lungs, do not undergo the same trauma from a sudden drop in pressure.

Some research groups are investigating ways to keep bats away from wind farms, and a University of Aberdeen group recently suggested radar emissions might act as a “bat-scarer”.