Window collisions are another human-led cause of avian mortality, killing about 599 million birds per year in the U.S. alone. A 2013 paper estimates between 16 million and 42 million birds die in similar fashion in Canada annually. @cornellupress.bsky.social https://www.theweathernetwork.com/en/news/nature/animals/helping-migrating-birds-prevent-window-collisions