Window strikes kill hundreds of millions of birds annually in North America alone, and simple, inexpensive deterrent solutions prevent the majority of collisions.
Window strikes cause acute trauma with a spectrum of outcomes: immediate death from cervical or cranial injury, delayed death from internal hemorrhage or concussion, and survival after a period of vulnerability to predation and weather during recovery. The individual suffering from non-lethal strikes — stunned birds left disoriented and exposed — is significant. The aggregate welfare harm from hundreds of millions of strikes annually is one of the largest human-caused sources of direct bird welfare harm, yet solutions are straightforward and inexpensive. Window films, external screens, closely spaced visual markers, and building lighting management each reduce strikes substantially. The barrier is primarily awareness: most window strikes are never witnessed or understood as preventable.