Wildlife

Migratory Bird Collision with Glass Buildings

Billions of birds are killed annually by collisions with glass windows and buildings, making this one of the largest human-caused sources of bird mortality.

Key Facts

An estimated 600 million to 1 billion birds are killed by building glass annually in the US
Birds cannot perceive glass as a barrier and fly toward reflected vegetation
Floor-to-ceiling glass buildings in cities create major collision hazards during migration
Collision-safe glass with UV-reflective patterns is invisible to humans but visible to birds
Simple remedies including window films, dots, and external screening prevent most collisions

Welfare Considerations

Birds killed by window collisions typically die from traumatic brain injury — sometimes immediately, sometimes after hours of disorientation and suffering from concussion. Survivors of collision often die from delayed internal injuries or predation while stunned. Collision prevention through window treatments is one of the most cost-effective individual actions available for reducing human-caused bird mortality.

What You Can Do

Apply window films or collision-safe treatments to large glass areas in your home or workplace
Advocate for collision-safe glass standards in building codes for new construction
Support organizations monitoring and mapping building collision risk in your city
Keep feeders within 1 meter or over 10 meters from windows to reduce collision risk
Rescue and care for stunned birds by placing them in dark, quiet containers for recovery