Wildlife

Window Strikes: A Hidden Bird Welfare Crisis

Between 100 million and 1 billion birds are killed annually by window strikes in buildings, making it one of the largest human-caused bird mortality sources.

Key Facts

US estimates suggest 599 million birds die from window strikes annually
Birds cannot perceive glass as a barrier and fly toward reflections of sky and vegetation
Patterned window film reduces strikes by over 80% in studies
Glass buildings during migration are particularly deadly for nocturnal migrants
Urban lights attract and disorient migrating birds, worsening window strike risk

Welfare Considerations

Birds striking windows at speed die instantly or suffer concussion, wing fractures, and internal bleeding. Concussed birds that survive the initial strike are vulnerable to predation while incapacitated. Many survive for hours in apparent recovery before dying from internal haemorrhage. The welfare scale — potentially over half a billion birds annually in the US alone — makes window strikes a significant but largely unrecognised animal welfare issue.

What You Can Do

Apply window film with patterns spaced no more than 5cm apart on problem windows
Turn off unnecessary interior lights at night during spring and autumn migration
Report window strikes to local wildlife monitoring schemes
Advocate for bird-safe glass standards in new building regulations
Support American Bird Conservancy glass collision reduction campaigns