Likely preditors... depending on where you live... Cats, Dogs, Owls, Hawks, raccoons, skunks, snakes, rats, fishercats, weasels...Not so likely bear, bobcat, cougar, cayote [sp],wolf
My yard is fenced so my girls can go just about everywhere they want to go... We have had a hawk scan the yard but my dog chased it off...they have always laid their eggs in the coop and gone back to the coop just before sundown...