I believe the hawk may have attacked their nest, and they were desperately trying to make it leave. I watched them for a good 2 or 3 minutes, a long time before he had had enough.
Great shot. They are ferocious defenders. My wife received a whack on the head just walking under a tree with a nest and I got the same venturing too close to an unseen blue jay's nest and I once witnessed a smack from a diving mockingbird cause our cat to do a complete back flip.
I believe the hawk may have attacked their nest, and they were desperately trying to make it leave. I watched them for a good 2 or 3 minutes, a long time before he had had enough.