I was dive-bombed by a pair while trying to herd their fledgling child out of the street. They clearly did not understand I was on their side. They may not be large birds, but they're pretty scary when they're flying around right over your head, shrieking like banshees!

My blue jays still do that sometimes, but at least one is even smarter than I thought. They used to perch above the sunflower seed feeders and mimic a Red-Tailed. The small birds would all scatter, and the mimic jay would swoop down and eat. After a while, though, the little birds started to figure it out; they'd hear the "hawk", but only a few would leave. One day, I was sitting outside on the patio, and heard the oddest sound; almost like a Cooper's hawk, but as if it had a head cold. I live right next to the woods, so Cooper's are common, and you can bet the birds know it, and respect the kik-kik-kik. They heard that, and they were gone. I heard them flying away en masse and looked down toward the feeders to see...a single blue jay, parked in one of the tray feeders, happily munching sunflower seeds.