Window strikes kill hundreds of millions of birds annually in North America alone. Understanding the scale of individual suffering and the simple prevention measures available makes this one of the most actionable wildlife welfare issues.
Window strikes cause two categories of welfare harm: immediate death from severe trauma, and prolonged dying from sub-lethal injuries. Birds that survive the initial impact but cannot fly away often huddle on the ground in a concussed state, vulnerable to predation, hypothermia, and organ failure from internal bleeding. These individuals suffer for hours before dying. The sheer scale — potentially over a billion birds globally per year — makes window strikes one of the most numerically significant sources of wildlife mortality and suffering attributable to human infrastructure. The prevention measures are practical and affordable: window films, screens, and bird-safe glass patterns can be applied to existing windows at modest cost and reduce strike rates by over 90%.