Wild Bird Window Strike Prevention: Simple Solutions for a Major Problem

Window strikes are estimated to kill up to one billion birds annually in North America alone, making residential and commercial buildings one of the most significant sources of human-caused bird mortality.

Key Facts

Birds cannot perceive glass as a barrier and fly into windows when they see reflected sky, vegetation, or a clear passage through a building
Up to 50% of birds that strike windows die immediately, with a further proportion dying from internal injuries in subsequent hours or days
Simple visual markers on glass — UV-reflective decals, tape, or external screens — applied in a grid pattern of 5cm or less provide effective deterrence
Buildings with floor-to-ceiling glass or glass corners are particularly dangerous, creating visual passages that birds attempt to fly through
Migration periods in spring and autumn see elevated strike rates as unfamiliar birds encounter buildings along unfamiliar routes

Welfare Considerations

Window strikes represent a preventable welfare problem on a massive scale. The solutions are available, affordable, and effective — the barrier is awareness and motivation rather than technical difficulty. Individual households and building managers who apply effective deterrence measures prevent dozens to hundreds of strikes annually at minimal cost. Scaling this intervention through building codes, design standards, and public education programs could dramatically reduce one of the most significant human-caused sources of bird mortality.

What You Can Do

Apply bird-safe window markers in a grid pattern with spacing of 5cm or less on dangerous windows at home
Turn off unnecessary indoor lights during migration season to reduce building attractiveness to nocturnal migrants
Advocate for bird-safe glass requirements in local building codes for new construction and major renovations
Place bird feeders either very close (less than 1 meter) or far from windows (more than 10 meters) to reduce strike risk