How window strikes kill billions of birds annually and what building design and individual actions can drastically reduce this hidden welfare crisis.
Window strikes cause instant death or serious injury for billions of birds annually, making collisions with glass one of the largest human-caused sources of bird mortality globally. Birds that survive the initial impact often die later from internal bleeding, brain injury, or predation while stunned. The welfare harm from window strikes is enormous in scale yet almost entirely preventable through straightforward design and individual choices. Buildings retrofitted with bird-safe glass or external films, and homes where feeders are positioned either very close to (within 1 metre) or very far from (over 9 metres) windows, show dramatic reductions in strike mortality. This is a welfare problem with well-understood solutions — the barrier is awareness and willingness to act.