When a hawk decided to visit our yard, we were too dumbstruck staring at it to notice that it had prey in its sights. I am guessing that the victim bird (most likely a dove, but it was a blur) was already hit when the hawk swooped in. The hawk sat on the fence for a minute and then hopped off--onto a bird. We let nature take its course, as it was likely too late--and watched the flapping stop and the hawk fly away with it. The hawk appears to be a Cooper's or sharp-shinned hawk, but I'm not sure of that id.