Window strikes kill hundreds of millions of birds annually across North America and Europe, representing a massive but largely preventable source of bird mortality and injury.
Window strikes cause birds to experience sudden, severe trauma. Fatal collisions account for a significant proportion of mortality, but many birds survive initial impact in a stunned state and die later from internal injuries, concussion, or predation. Birds found stunned after strikes require quiet, dark, contained recovery time before release, and veterinary assessment if they do not recover within two hours. Prevention through window treatment is far more effective than treating casualties, and simple modifications can reduce strike rates by up to 90%.