I have 4 chickens in a rather large coop. (The coop is rated for up to 8-12 chickens!) Have had them for about a year and a half. I have noticed that 2 of the chickens have been plucking the feathers from one of their room mates! They have lots of space, good food, clean water, clean boxes.....! Not sure how to stop this unless I actually buy a small coop just for the poor girl being picked on! But then she will be alone! What should I do?