By your profile I cant tell what state you live in. That might help. Wooded, desert, prairie.... Second do your birds free range? If so are they disapearing while out foraging? Few preditors can kill or snatch a chicken with out a mess of feathers. Bob Cat or coyote. check all the area where they free range. Even the big ones cause some feather loss. No to the coopers hawk it has a body the size of a pigeon. By the way I am sorry for your losses. It sometimes takes a few losses to tighten up the coop and pen.