I have a total of 6 chickens. 4 of them are 6 months old, 2 of them are 16 weeks old. They have been together for at least a month now after being transitioned. We rescued a broiler chicken (I didn't know what kind she was, she is 6 month olds and has been with the flock since she was just a few weeks of age-I do not intend on eating her). A few weeks ago I noticed she lost some feathers on her back but I never saw aggression from any other hens towards her. It was an area I have seen her reach back and nibble so I thought maybe she was doing it herself, until one day I came out and she was bloodied, VERY BADLY! I took her out of the flock and put her in her own separate area, started treating her and she is healing up wonderfully. Now my 2 younger ones all of a sudden are starting to lose feathers and this morning I saw blood on 2 of them-nothing like the broiler, she was very brutally attacked. I saw only one time another hen peck one of them this morning. Before I left the house I separated them in their own area. My question is, how can I break this type of behavior? The one I saw peck (just once) seems to be maybe bullying my other girls. Is this broody behavior? They have plenty of room in their coop, its 6'X8' with 3 nesting boxes, 2 roosting bars, almost 6' tall, their run is VERY large, almost triple the size of the coop. I believe they have enough room. Please help!