Wild Bird Window Strike Prevention and Welfare

How to prevent bird window collisions, one of the largest human-caused sources of bird mortality and suffering.

Key Facts

Window strikes kill an estimated 600 million to 1 billion birds annually in the United States alone.
Birds cannot perceive glass as a barrier and fly into reflections of sky and vegetation at full speed.
Collision mortality is concentrated during spring and fall migration when bird density and movement peaks.
Bird-safe glass with UV-reflective patterns is invisible to humans but visible to birds.
Exterior window treatments including tape, decals, and netting effectively reduce collision rates.
Turning off indoor lights during migration season dramatically reduces night collision mortality.

Welfare Considerations

Window strikes cause immediate death in some cases and prolonged injury and suffering in others. Birds that strike windows and survive immediately may die hours later from internal hemorrhage, brain injury, or delayed shock. Injured birds found stunned after strikes require careful supportive care in quiet, dark containers before release. Prevention is far more effective than rehabilitation at scale, and most effective prevention measures are low-cost. Interior decals placed at 2-inch spacing cover enough glass surface area to alert approaching birds. Exterior treatments including window screens and netting provide the highest protection. Building-level bird-safe design using fritted or UV-patterned glass achieves prevention at source.

What You Can Do

Apply bird-safe window treatments to glass surfaces where strikes have occurred or are likely.
Place decals or tape at 2-inch spacing to create visible patterns detectable by approaching birds.
Turn off interior lights visible from outside during peak migration periods to reduce night strikes.
Advocate for bird-safe building standards in new construction and major renovations.