Got to see something interesting yesterday. Was out with a friend to band Eastern bluebird chicks at a local park. Spent a little time in the park beforehand. Heard a Broad-winged hawk's distinctive whistle call, but did not see the bird.
As we were getting ready to band the chicks, saw the Broad-wing overhead, making several passes. Then saw a second bird; you can tell from the primaries molting in on both sides that it is another bird.
Then - saw a Cooper's hawk. Not uncommon to find them both in town, obviously. But in the same airspace? I did wonder a little bit how that would work out.
And here we have it - a real dogfight. One of the Broad-wings whistled during the whole thing but the Coops didn't say much. Probably only lasted about five minutes. Not sure who the winner was; both birds drifted off. One of the Broad-wings came by a few minutes later and was not chased off.