I have a mixed flock of hens who are just about at the 1-year age. One of my RIR's suddenly has become quite aggressive, mounting the other hens and pecking their necks. I am at the point where I may have to cull her just to have sanity back in the flock. Any suggestions? I have tried separating, but this has thrown the flock off to the point where egg production dropped, so I opened the coop back up to all, and they are again laying as before. There are several hens with bald areas on their necks from her attacks! I also could swear I heard a crow the other day.......