The little guys think the owls are going to eat them. The big guys think the owls are going to eat their food. Both situations are largely true.

But it’s not exclusive to owls. I watch my bluejays chase off crows and hawks. If you and your neighbors all saw a scary looking dude looking like he was about to scuffle with someone, you might ask him to take a hike using your power of numbers. The birds do the same.

Here’s a little article on mobbing.