These are *very* low rez, shot with a Pana TZ5 pocket camera from about 200 ft away, in heavy shade, cropped from ~3500 pixels wide to 1280 wide. It's a miracle they were salvageable at all.
I'm adding these here because they were also taken at the L.A. Zoo, about 1/2 hour before the Grackle photos, and these are obviously not a caged bird. I get a lot of wild animal images at the L.A. Zoo, which is interesting. I suppose the hawk sees a lot of potential meals around there, apparently a squirrel in this case.