Wild Bird Window Collisions: Reducing a Major Mortality Cause

Window collisions kill billions of birds annually worldwide. Simple modifications to windows and buildings can dramatically reduce this preventable source of wildlife mortality.

Key Facts

Window collisions kill an estimated 600 million birds annually in North America alone
Birds cannot perceive glass as a barrier and fly into reflections of sky and vegetation
Collisions are most deadly when birds strike at high speed
Many birds that appear stunned after collision die later from internal injuries
Window films, external screens, and visual markers can reduce collision rates by over 90%

Welfare Considerations

Birds that collide with windows suffer traumatic brain injury, internal hemorrhage, broken bones, and beak fractures. Many die immediately while others suffer for hours or days from their injuries. Even birds that appear to fly away after a collision often die later from delayed brain hemorrhage. The scale of this problem makes it one of the largest anthropogenic sources of bird mortality globally. Simple, inexpensive solutions applied to the most dangerous windows in homes and commercial buildings can prevent enormous numbers of needless deaths and reduce the suffering of billions of birds.

What You Can Do

Apply external window films or screens that break up reflections
Use WindowAlert UV decals or acopian bird savers on problem windows
Position bird feeders either very close to windows or far away to reduce fatal collision speeds
If you find a stunned bird, place it in a ventilated box in a dark quiet space for recovery
Contact a wildlife rehabilitator for birds that do not recover within an hour
Advocate for bird-safe building design standards in new construction