How bird-window collisions cause billions of deaths annually and what practical measures can prevent them at homes and commercial buildings.
Window strikes cause acute traumatic suffering on a massive and largely invisible scale. Birds that die instantly upon impact represent the most welfare-benign outcome; birds that survive the initial collision and die slowly from internal injuries hours or days later experience extended suffering. The scale of this problem — approaching a billion deaths annually in North America alone — and the availability of practical, affordable solutions make window strike prevention one of the highest-impact individual wildlife welfare actions available to building owners and occupants.