Welfare of Wild Birds During Window Collisions

Window collisions kill an estimated 600 million birds annually in the United States alone, making them one of the leading human-caused causes of bird mortality.

Key Facts

Birds cannot perceive glass as a barrier and fly toward reflected sky and vegetation
Up to 600 million birds die from window collisions in the US annually
Mortality is highest during spring and fall migrations when billions of birds are in transit
Bird-safe glass with ultraviolet-reflective patterns is visible to birds but nearly invisible to humans
Collision monitoring programs like Project Feeder Watch help track mortality at individual buildings

Welfare Considerations

Window collision death is rarely instant — many birds are concussed and die slowly from brain injury, internal bleeding, or predation after impact. Birds that survive the immediate strike often need rehabilitation. Building-level interventions — window film, exterior screens, patterned glass, turning off lights during migration — are highly effective and relatively inexpensive. New building codes in cities including San Francisco and Toronto now require bird-safe glazing.

What You Can Do

Apply window film or bird-safe decals to glass that causes frequent collisions at your home
Turn off unnecessary interior lights during spring and fall migration seasons
Support local building code campaigns requiring bird-safe glazing in new construction
Participate in citizen science collision monitoring through Fatal Light Awareness Program