Birds often collide with buildings because they have difficulty distinguishing glass from open air, mistaking reflected sky or vegetation for the real thing.
Light from buildings at night can also draw migratory birds into urban areas, where collisions are more likely.
A 2024 study estimated that over one billion birds are killed annually as a result of colliding with buildings in the US alone.
This is larger than previous estimates as it considers birds found dead at the scene, but also those that survive the collision only to die later in rehabilitative care.
The researchers call for more buildings to be made bird-friendly, such as by adding visual markers to windows.
This article is an answer to the question (asked by Barry Maegan, via email) 'How many birds fly into buildings?'
To submit your questions, email us at questions@sciencefocus.com, or message our Facebook, X, or Instagram pages (don't forget to include your name and location).
Check out our ultimate fun facts page for more mind-blowing science
Read more:
