Glass windows and buildings kill an estimated one billion birds annually in North America alone, making window collisions one of the largest preventable sources of wild bird mortality.
Window strikes cause blunt force trauma resulting in internal bleeding, brain injury and broken necks. Birds that appear stunned and recover may have sustained internal injuries that cause delayed death. The scale of this mortality is staggering and largely invisible — birds fall, are consumed by predators or removed before observers notice them. Critically, the solution is well-established and inexpensive: applying visual patterns to glass surfaces at 5 centimeter intervals breaks up reflections and allows birds to perceive the barrier. Building design and retrofit programs can reduce collisions by 70 to 90 percent. Individual action at home combined with advocacy for bird-safe building standards can collectively save hundreds of millions of birds annually.