i believe this is some form of falcon... a merlin, perhaps? it was MUCH too fast to be any other kind of hawk that i know of. doesn't really look like a peregrine, unless it's a young one? it didn't dive on its prey like a peregrine, seemed to mostly just chase it in level, banking flight. it made several passes, including one about 25 yards away at about 10 feet altitude and what seemed like 80+ mph... too close and fast for me to pan with. the second shot isn't terribly clear, but it does show the colors on the back and upper wings better than the others.