It was a warm day with a breeze and I was in a classroom where someone left the window open. The vertical blinds were flapping so I opened them horizontally all the way. I didn’t understand why I was getting horrified looks from the class until I realized a bird had dived into the window. I turned around and saw a feather floating, and then I knew the terrible event I had caused. I reclosed the blinds.

Predators have eyes positioned in front of their heads to triangulate distance to prey. Predated animals like many birds, have eyes on the sides of their heads to get a 360 degree view for potential predators. That ability to see all around may be a tradeoff for depth perception which might help a bird understand that the approaching bird it sees  is actually its own reflection.

There may be a lesson for drone builders here.

More about birds and windows.