This is a female hawk. She and her mate have just, um, mated, right in front of our house! (And wow, the male bird makes QUITE a racket--who knew? Ah, nature.)
I wonder if this is their nest...it's several blocks away, down in a canyon and way up high in a eucalyptus tree. We seem to have lots of hawks in the 'hood, though, so this might be a different amorous pair.