a rooster could work ,but i hear so many aggressive rooster stories or at least he would sound the alarm the hens that hawks are overhead.are your chickens free range or penned?.mine are free range with the pen and hen house access and we have hawks too, usually one of the hens will spot the hawk overhead and start clucking, then they all run for cover under bushes,trees, shrubs, even our kids play structure works for them. As far as dogs go we have a beagle female "field beagle"I'm told, their heads and muzzle are more narrow then traditional beagle,she's a good girl,got her as a pup exposed her early to the chickens never had a problem with her getting out of hand.But she seems TOO interested in small chicks I dont allow her to touch or sniff the chicks.
Never lost a chicken to a hawk,hawks stole a duck once ,FAT DUCK hawk picked her up made it about 20 feet up in the air,about 50feet across the yard and dropped her must of weighed about 12lbs.!! no worries she was fine quacked alot and shook it off. scary though .kimm