Window strikes kill between 100 million and 1 billion birds annually in the US alone, making them one of the leading anthropogenic causes of bird mortality.
Window strikes cause immediate death in some birds, but many are stunned and die later from internal injuries, concussion, or predation while incapacitated. The scale of mortality - from individual house windows to glass skyscrapers - represents a massive preventable welfare and conservation problem. Simple, inexpensive interventions can reduce strike rates by 80-90%.