Wild Bird Window Strikes: Prevention and First Aid

Window strikes kill an estimated 600 million birds annually in North America. Simple prevention measures dramatically reduce this massive source of bird mortality and suffering.

Key Facts

Window strikes are the second largest human-caused source of bird mortality after feral cats in North America
Estimates range from 400 million to 1 billion bird deaths from window strikes annually in the US
Birds cannot perceive glass as a barrier and fly into reflections of sky and vegetation
Migration periods in spring and autumn dramatically increase strike frequency
The American Bird Conservancy rates window products for effectiveness using a 2x4 standard
Fritted glass, external screens, and vertical tape or decal spacing of 5cm or less effectively prevent strikes
Overnight lighting of buildings during migration attracts and disorients birds, increasing collision risk

Welfare Considerations

Window strikes cause traumatic brain injury, broken bones, and internal injuries in surviving birds. Many die immediately from impact. Those that survive often experience hours of disorientation, pain, and vulnerability to predation during recovery. The scale of mortality - hundreds of millions annually - represents an enormous source of preventable wildlife suffering. Unlike many conservation problems, window strike prevention is directly actionable by individual households and building owners, making it one of the most impactful individual welfare interventions available.

What You Can Do

Apply external window films, tape, or decals at maximum 5cm vertical spacing on problem windows
Move bird feeders to within 1 meter of windows so birds cannot build collision speed
Install external screens or netting on large glazed surfaces to prevent strike at high-risk windows
Turn off unnecessary lights in commercial buildings during spring and autumn migration nights
If a bird strikes and survives, place it in a dark quiet box and allow 1-2 hours recovery before release
Contact a wildlife rehabilitator if a bird shows neurological signs or cannot fly after 2 hours
Use bird-friendly glass with ultraviolet patterns in new construction and renovations