Glass windows and buildings are estimated to kill hundreds of millions of birds annually in North America alone, representing a preventable welfare and conservation problem.
Window strike deaths involve significant suffering even when not immediately fatal. Birds that survive initial impact may suffer concussion, internal bleeding, broken bones and disorientation leaving them vulnerable to predation. The scale of mortality — hundreds of millions of individuals per year — makes this one of the largest preventable sources of wildlife death in developed countries. Critically, the solutions are low-cost and effective: patterned window film or closely spaced external decals reduce strikes by up to 90%. Building design that incorporates fritted glass or external screens virtually eliminates the problem. Individual homeowner action combined with updated building codes can dramatically reduce this welfare impact.