I don't know the solution!
This is the first year we've had chickens. Mine are in an uncovered 20'x30' run, and I let them free range in the evenings. I'd leave them out all day, but my dogs don't play well.
Anyway, I put two Igloo dog houses in the run, and when ANY bird flies overhead, mine run into either the coop, or the dog houses, which ever they are nearest. While free ranging, they'll run UNDER something. Sometimes a chair, under the coop, into the dog houses, under a vehicle, etc., but so far, they've managed to escape being caught by whatever is flying overhead. Now a few blue jays are being stupid, and flying into my chicken's run! The chickens actually chase them out.
And I'm so stupid, I don't know what a hawk sounds like. I've seen one, or what I thought was one flying one day. And we found one dead on the side of the road that someone had hit. But when I'm outside, I hear all kinds of birds singing, so I odn't know if one is a hawk.