Window collisions kill an estimated 1 billion birds annually in North America alone — making glass buildings one of the leading human-caused bird mortality sources.
Window strikes cause acute welfare suffering — death in many cases, serious injury in others including concussion, internal hemorrhage, and broken wings that prevent survival even after initial recovery. Birds that survive initial impact often die within hours from internal injuries or abandonment during critical developmental periods for migratory instinct calibration. The scale of mortality is enormous — among the top three human-caused bird mortality sources alongside cats and vehicle strikes. Unlike many wildlife threats, window strikes are almost entirely preventable with available technology. Building design and glass treatment solutions are commercially available and increasingly cost-competitive with standard glazing. The welfare argument for bird-safe glass is compelling and the regulatory trend is toward mandating it in new construction — cities including New York, San Francisco, and Toronto have adopted bird-safe building standards.