My chicken Henny, who died two years back.She flew in until I made a ramp for the flightless chickens. so she had to learn as well so I got her to climb by putting watermelon at the top. And every time she flew to get it I would take the melon away so she sneaked up on it very slowly then she...
all you have to do is staple netting to the top of your run. Put support beams across the run so the netting does not cave in when it snows and voila the hawks can't get in!