Glass windows kill hundreds of millions of birds annually in the UK and US, making collision prevention one of the most impactful urban wildlife welfare interventions available.
Birds that strike windows suffer blunt force trauma, internal haemorrhage, and brain injury. Many survive the initial impact but die hours later from delayed injuries. Survivors may be stunned, vulnerable to predation and weather stress. Even sub-lethal strikes can impair navigation and foraging ability during critical migration periods.