Barotrauma explains bat fatalities

The question of why large numbers of migratory bats are killed by certain turbines of southern Alberta’s wind farms every year has been answered by a University of Calgary researcher.

Biology professor Robert Barclay has determined that the vast majority of bats found dead below the turbines near the Canadian Pincher Creek wind farm suffered severe injuries to their respiratory systems consistent with a sudden drop in air pressure - called barotrauma - that occurs when the animals get close to turbine blades.

His studies showed that 90 per cent of the bats examined after death showed signs of internal hemorrhaging consistent with barotraumas while only about half of the bats showed any evidence of direct contact with the blades.

Because bats can detect objects with echolocation, they seldom collide with man-made structures. However, an atmospheric-pressure drop at wind-turbine blades is an undetectable - and potentially unforeseeable - hazard for bats, partially explaining the large number of bat fatalities at these specific structures.