We have a pair of female ducks, 6 chicken hens and a rooster in a combo coop. They have more than enough room in the coop and the outsid run. I recently notice s that our one duck has been pulling and eating feathers from our hens! 2 of our hens aphave bare spots on their backsides and another hen has a spot started on her back near her tail feathers. I noticed it the other day and then today saw our duck pull and eat the feathers of 2 hens. What is causing her to do it and what can we do to stop it? It is the middle of winter so separating would be very difficult because of the cold and the snow.