Wild Birds

Wild Bird Window Strikes: Scale and Solutions

Window strikes are one of the leading human-caused causes of wild bird mortality, killing hundreds of millions of birds annually worldwide.

Key Facts

Window strikes kill an estimated 100-1000 million birds annually in North America
Birds cannot perceive glass as a barrier and collide at full flight speed
Reflective glass mimicking sky or vegetation is particularly dangerous
Simple external patterns including tape and netting reduce strikes by over 90%
Migrating birds at night are particularly vulnerable to illuminated buildings

Welfare Considerations

Birds that strike windows at full speed typically suffer traumatic brain injury and die immediately or within hours. Survivors often cannot fly and die from exposure, dehydration, or predation. Birds appearing stunned after window strikes may be in a fatal condition even when they appear to recover. The scale of window strike mortality — affecting common and rare species equally — makes building design a significant bird welfare issue.

What You Can Do

Apply external window markers or films in patterns at appropriate spacing
Turn off unnecessary lights in tall buildings during migration seasons
Place bird feeders either less than 1 metre or more than 10 metres from windows
Report window strike casualties to national bird recording schemes
Advocate for bird-safe glass requirements in new building planning