I put netting over top our run. Just don't offer them an easy meal. It is against the law to trap/kill a hawk so I hear. I understand your frustration as we lost alot two years ago to hawks so we fenced them in and put netting over top and now hawks have moved farther away but see them now and then.Good luck!
I have been told that mirrors and other shiny things reflecting light skyward is a repellant. I threw a bunch of old CDs on top of the netting in my run for that reason.
Having plenty of places where the chickens can take cover is also helpful. Hopefully your roos will spot the hawks and sound the alarm before it's too late.
A tom turkey is supposed to be helpful too. But if you free range chickens at least around here, losing an occasional chicken to a hawk is probably unavoidable. The key is to make your chickens one of the more difficult meals in the neighborhood.