I have nine chickens - three have been together since they were chicks, 1.5 years ago. The other six have been together since they were chicks, 6 months ago. All nine have been sharing a fairly large coop and run since early summer. There was one rooster in the first set of three, and I recently realized I also have one rooster in the younger set of six. I haven't noticed the two roosters fighting, but the younger rooster has been very aggressively pecking/chasing one of my older hens recently. She is missing a lot of feathers, and she has recently taken to hiding under the coop. I am not certain she is coming out for food or water. As far as I can tell, he is not picking on any of the other hens. I am uncertain what to do at this point - should I separate him permanently, or should I try a temporary separation and then slowly reintroduce? Any advice would be helpful.