I tried to let my chickens free range. My neighbors did for a few hours a day when they were home. We did fine for a while and then the coyotes discovered my chickens and they got 3 with in a week. I now let them out in a temporary electric fenced area with a kit that I bought from Ken cove. It keeps them from going too far, the dogs from chasing them and if I am home the preditors from grabbing a quick meal. I dont let them out unless I am home. If they fly over the fence then they are fair game and I have lost 1 hen and 2 roos in the year since I started this system. My neighbors and I have seen bobcats and coyotes in broad daylight so don't think they wont be checking out your flock.
I let most of my hens free range, but I have a fence and a nice big white dog great Pyr in with them.