I have 17 BLRW and 3 BCM chicks that are about 10 weeks old. They are all the same age and have all been together since day olds. They are just getting to the point where I think I can start telling the sex. About 2 weeks ago I moved them from the brooder to the chicken house. They have all been fine with eachother, no problems at all until a couple days ago. It started with the BLRW's picking on one of the BCM's which the BCM's are almost twice the size of the BLRW's (I guess they grow faster). I took the one being picked on out and went back the next day and there are a few more that are being picked on. I sat and watched to see who was doing the picking and it seemed to be several of the BLRW's. I still have them confined to the coup and was wondering if being confined all the time was the problem. The coup is good size at 10' x 12' which should be plenty for 20 chickens. I have the premiere 1 electric netting for a yard around the coup and when I let them out a week ago they were still small enough to fit through the holes in the fencing, hence the reason I'm still keeping them in the coup. How can I stop the pecking?