I had a coyote jump over a 5 foot fence into a pen before I covered the pens during the day. Many of the birds went over the fence to escape the coyote and the coyote went back over the fence to chase them. It was chasing the birds around through my back yard. I had some bird shot in my shotgun and shot it but didn't kill it and it ran off. Some birds died that day and some the next from injuries.I let mine free range for years until one day they were massacred so that ended the free ranging. Some were able to fly over the fence but whatever killed them, chased them over the fence after killing the chickens inside the fencing.
And then I lost one to a fox during the middle of the day while I was home.
I'm moving, and at my next place, they will be contained inside an electric fence with lots of bushes to hide under should there be a hawk. My chickens are always up now if I am not at home.
Having a goat or other animal in with the chickens I believe helped prevent predators.