Bird-window collisions kill an estimated 600 million to 1 billion birds annually in North America. This is one of the most solvable mass wildlife welfare problems, with proven prevention solutions at every scale.
Bird window strikes cause immediate death in approximately half of collision cases; the other half suffer varying degrees of injury including concussion, internal bleeding, and disorientation that often leads to delayed mortality from predation or exposure. The welfare harm is both acute — the impact itself — and chronic for injured birds who cannot feed, thermoregulate, or flee predators effectively. What makes window strikes a particularly tractable welfare problem is the availability of proven, cost-effective solutions. Unlike many wildlife welfare challenges that require large-scale policy or habitat change, window collisions can be addressed at the individual building or even window level. Homeowners can apply inexpensive window films or decals; architects can specify bird-friendly glass for new construction; municipalities can implement Lights Out programs during migration.