I have five 20 week old barred rocks. Recently they started being allowed to free range toward evening when I get home from work (too many predators during the day). When the sun goes down, 4 of them do what chickens do,and they go in to their coop and settle down for the night. Just one of them goes around back of the coop and goes up high on what is like a roof on the coop. She goes to settle down for the night there,but she's not protected and would get eaten if left there.I have to climb up on the coop and go get her and put her in the coop. I tried adding light inside the coop at dusk, but it did not change her mind. She still went around back and on top of the coop. Does anyone know why she would do this, and/or what I might do to encourage her to go in with the others?