Glass windows kill an estimated one billion birds annually in North America alone. Simple and affordable interventions can dramatically reduce this human-caused mortality and suffering.
Window strikes cause acute trauma including concussive brain injury, spinal damage, and internal haemorrhage. Birds found stunned after window strikes experience fear, pain, and disorientation during their recovery period, which may last hours. Many apparently recovered birds succumb to internal injuries days later. The scale of mortality from window strikes exceeds that of domestic cats in some estimates, yet receives far less attention. The welfare dimension of window strikes is therefore substantial: millions of birds experience painful deaths or distressing injury from an entirely preventable human-caused hazard. Simple low-cost preventive measures including patterned window film, external screens, and fritted glass can virtually eliminate the problem.