Think about turkeys. I used to have a hawk that perched in an apple tree INSIDE the chicken pen. Once the turkeys came, he decided to not sit there anymore. The turkeys would warn everyone when they sighted suspicious aerial behavior, too, so that they could all run under the trees. My current bunch are younger and clueless, but I have geese who are young but not clueless. I really like my geese, but turkeys are the best! They are gentle and sweet. When I go out they all follow me around, as do most of the chickens. The geese are good, too, but they know that I am not a goose. The turkeys think I am part of their flock.
The other thing I did when I had no bib birds is to randomly string wire across the top of the run. That way he hawks would see the wire there, but they were never sure if they could get through it. It was cheap and effective. they would swoop down and study it but I never had one brave enough to try and go through it. The size of the wire didn't seem to matter. When I had small/fine wire I used to tie rags or string on it.
Having said all that, remember it takes a while for Jerseys to grow. They are slow, slow slow to get big. I think they are worth the wait but if the hawks eat all yours before they are grown it would be sad.
