How do wind turbines affect birds and bats?

Mountain ridges and coastal areas, where industrial turbines are often installed, are landscape features which can concentrate many birds, and songbirds – which mostly migrate at night – are prone to fly low enough to collide with the blades and towers of tall wind turbines. The clearing of forest to install wind turbines and development infrastructure represents a potentially enormous threat to the ecologically significant forest-interior habitat. The activities of prairie birds, including mating and nesting, are easily disturbed at great distance from the construction and continuing operation of an industrial wind power facility, which can spread over hundreds, often thousands of acres. In addition, windplants may cause birds to avoid foraging or migrating through the site. This exclusion or displacement may result in birds expending extra energy to fly around the facility, and may block them for using areas for feeding or roosting.