Bird collisions with glass windows kill an estimated one billion birds annually in North America alone, representing the second largest source of direct human-caused bird mortality after cats.
Window strikes cause traumatic brain injury, internal bleeding, and broken bones. Birds that do not die immediately often die from delayed injuries or become easy prey while incapacitated. The suffering is acute and widespread, affecting billions of individual birds every year — yet the problem is almost entirely preventable through relatively inexpensive modifications to existing glass.