Hawk ID
I have looked at a number of our local (i.e. North American) Accipiter sp. over the years, but never one with a tail pattern like this one. Just looking at the first photo, I thought the 'X' might be an illusion, but it shows very well in the sharpened image. I suggest that this indicates something 'odd' about the central tail feathers, although I cannot say why (but might they be still coming in? Lost adventitiously and recently replaced?). But if there were something 'not quite right' about the central rects., it could explain the Sharp-shin-like notched appearance in the photos, especially #1/4. Kenn Kaufmann, in the Peterson's Advanced Birding guide, depicts the tail of young Cooper's as having more 'bent' bands in the tail (compared to S-s), i.e., the banding is less straight because the dark areas do not line up as well. I suspect this individual may be an extreme case of this tendency.
Anyway, I agree that this bird does show a mix of features, and all that, but head projection and tail structure make me think Cooper's. (That fence was looking pretty shaky with all those people on it...) Also, belly/vent streaking seems less than in other young Sharp-shinned I've looked at, although I doubt this is a reliable character.
Cheers,
Peter C.
PS. By the way, Scissortail, when I asked about flight, I perhaps didn't make myself clear enough; I was asking about flight style - was it soaring a lot, did it flap and then glide, were the flaps slow or fast, that sort of thing. Flight style can, all by itself, tell you if you're looking at an accipter or some other kind of hawk (like a Red-shoulder, or even a migrating Harrier), which is a good way to start with raptors.