I've come to the conclusion that the hawk that's been visiting the yard and stalking the sparrows and doves is a Sharp-Shinned Hawk. The other day Jake found the hawk standing on our bench in the backyard. He was afraid the hawk would carry off the dog, but I don't think it could fly off with a 14 pound terrier! The males hunt small birds like sparrows and warblers (I see yellow rumped warblers every morning in the eucalyptus trees hunting for insects) and the females go for larger birds like robins. I'm thinking that this is a female because she is going after birds as large as mourning doves.
We had a "city pigeon" show up a couple of months ago by itself. I thought that maybe it had been ostracised by it's flock. It flew in everyday and looked so funny and out of place along side the mourning doves and sparrows and finches. It's a completely dark grey handsome bird. I've never seen one quite like it. A few weeks ago it showed up with a friend. They've been coming by together ever since. I believe they're both Rock Doves which were originally introduced by European settlers. I researched that Rock Doves mate for life until one of them dies. These two loners somehow found one other and hit it off. I like to think about what their back story might be...I know it's so terribly anthropomorphic, but I just can't help it. I have so much respect for city pigeons. They are truly survivors in this insane human world.