Bats and birds aloft: reactions to wind turbines and unexpected high-altitude antics
In Illinois and other places in eastern North America, several species of common bats are killed in large numbers by commercial wind turbines, but migrating birds are seldom killed. Our research comparing the behavior of the two groups has revealed that bats are, at least sometimes, attracted to turbines from a distance of several hundred meters, whereas birds are not attracted and indeed can turn away to avoid turbines.
We discovered and quantified remarkable long, erratic local flights by the bats including swoops, hovers, and prolonged climbs and descents--behavior that is almost certainly prey-capture and/or social behavior, often at heights of half a mile or more above the ground. There are indications that bats in other parts of the world catch prey high aloft but this behavior by some North American bats was previously unknown.