I also let them free range with a protective rooster for seven years with no incident. But this past November a hawk killed of my hens. Traumatized the whole flock who ran off and hid and fortunately came slowly back to roost in the evening. So into the coop they went to stay for the rest of the winter. A neighbour told me hawks are less likely to attack chickens in spring and summer when there is young prey in the fields. So maybe I'll let them out in the spring.