We have a bunch of crows that live in a neighbors tree nearby. They are often heard cawing and conversing. There are always two or three birds hopping around our front yard, doing their crow thing. This morning there was a big crow commotion in the trees so my sister (who is visiting) went out to see what all the fuss was about.
Apparently there was a hawk- a rather large one, too close to their territory. They dive bombed him while he sat in a nearby palm tree. They worked in groups, switching out periodically. They would swoop down from straight above him then just when it looked like the crow would crash into the tree it would pull up from the dive cawing loudly.
This carried on for over 10 minutes. The hawk went from one palm to another, 3 in all. Eventually the crows stopped, though they were spread out through the neighborhood, keeping an eye on the tree. The hawk moved around a bit at one point, without leaving, and 3 crows flew out of no where and started in again. It was pretty fascinating to watch. It kept my sister and I out in the cold, misty morning air for a good 15 minutes!