Building and vehicle collisions kill an estimated one billion birds annually in the United States alone, making them one of the leading causes of bird mortality and individual animal suffering outside of hunting and habitat loss.
Building collision deaths cause a spectrum of welfare impacts. Instant fatalities from high-speed impacts represent sudden death without prolonged suffering. More commonly, stunned or injured birds experience minutes to hours of distress, vulnerability to predation, and often slow death from internal injuries or exposure. The scale of the problem — a billion birds per year in the US alone — means that even a small proportional reduction in collision rates translates to millions of individual animals spared from injury and death. The interventions are well-established, low-cost, and effective, making the continued high collision mortality largely a matter of insufficient public awareness and building code requirements.