Glass windows cause the deaths of hundreds of millions of birds annually — a preventable welfare harm with practical solutions available at household scale.
Bird window strikes cause welfare harm ranging from immediate death to prolonged concussion, disorientation, and delayed death hours after the collision. Concussed birds that survive the initial impact are vulnerable to predation, exposure, and secondary injury while recovering — a welfare period extending hours beyond the strike itself. The scale is enormous: if 600 million birds die from window strikes annually in the USA alone, the cumulative welfare impact is substantial even for those who do not assign high moral weight to individual wild birds. The practical welfare prescription is unusually clear: external window treatments that break up the reflective surface are effective, affordable, and available widely. The primary barrier is awareness rather than cost or feasibility. Building design codes incorporating bird-friendly glass requirements represent a systemic solution, but individual household action is immediately impactful.