Paul Cryan was surprised and curious. Cryan had been studying bats since 1990, but only in 2003 did he learn that bats were being killed at wind energy farms. Cryan wanted to know why the bats, whose visual and echolocation abilities allow them to find and catch flying insects at night and avoid obstacles in the dark, run into or otherwise are killed by rotating turbine blades. Why would bats be around wind turbines in the first place? And which species were most at risk?
Not just bats but also birds are killed at wind farms, which have been touted as more environmentally friendly energy sources than coal, oil, and gas. After all, wind turbines produce no air, water, or thermal pollutants, and emit no greenhouse gases. “If we don't do wind, we'll wind up doing coal,” warns Robert Thresher, director of the National Wind Technology Center at the US Department of Energy's National Renewable Energy Laboratory in Golden, Colorado. Wind farms may fragment the environment, however, and make it unusable for some birds.