Window strikes kill an estimated 600 million birds annually in the US alone. Simple, affordable deterrents prevent this largely invisible welfare problem affecting both migratory and resident birds.
Window strikes cause acute traumatic injury — brain trauma, internal bleeding, and organ damage from high-speed impacts with a surface that offered no visual warning. Birds that do not die immediately may be concussed and vulnerable to predation, or die from internal injuries over hours. The scale of the problem — hundreds of millions annually in North America alone — makes glass a significant source of individual wildlife suffering that is almost entirely preventable. Buildings in flyways during migration concentrate strikes during the periods when large numbers of birds are moving through the landscape. Individual households can eliminate the majority of their strike risk through affordable deterrents, and large buildings have an outsized responsibility given their disproportionate contribution to the mortality total.