I've had the same issue but couldn't figure out who the culprit was, so re-homed some I thought were doing it and found it still happening, so re-homed about 5 more. I picked them because they still had all their feathers when the rest of the girls did not! Soooo left this weekend for the 1st time and came home to a happy hen house, all was well!! Do what you are doing with separating her, but if she continues, then I would re-home her! We do not eat our chickens DD is a vegetarian otherwise I'd say make stew!
