I have a large hen whose feathers right above her tail and up her back are missing. There is not a roo in with her just other hens and they all seem to get along. None of the other hens look like her. Her feathers are picked/missing clear down to the skin. Doesn't look like mites. I just got her about two weeks ago with another of the same kind and powdered the both of them before placing in with other hens.