I am a first time chicken owner. I have 8 chickens in a very well made coop by my husband (thanks to a design on this page). They have a nice outdoor run area. They are 9 month old chickens (combo of red stars, americauna and australops). For about two months we have had a problem with a bully hen but have been unable to pick her out of the crowd: one by one all of our hens are developing bare backs. Today I went out to my coop to collect eggs and it looked like a chicken massacre. I was instantly terrified on what I would found and thankfully it was not as bad as it looked. One of my australops had a torn comb and broken beak...needless to say she was bleeding pretty badly and likely was attacked. I removed her instantly and placed her in a safe place. Provided her with food and water and plan to keep her seperated for a few days to let her heal. I spent time with my birds and looked at each of them closely to find I had only 1 hen without a bare back. To my surprise she was my smallest red star. I have friends who have chickens and they immediately offered to rehome her and give her a second shot. Now my questions are these: I have 7 hens with bare backs---some more severe then others. I live in MN and it's cold. Will the feathers grow back on their own? Do I need to put something on them to heal them? There are no major open areas that I can see? Is this a behavior the whole flock has likely picked up or by getting rid of the problem hen maybe I have solved my problem? My bird that was injured looks to otherwise be in good spirits --I have her in a dog kennel in my heated garage with food and water / hay . Do I need to do anything else special for her or do I just let her heal? When re introducing her do I just stick her on the roost in the middle of the night? Sorry for the million questions. I had a slight panic this evening I have attached a picture of her back which is by far the worst out of the group.