I have 6 -18 wk old hens and a rooster in with 4 -13 wk old hens and rooster, so obviously the 18 wk olds are the dominate. The 18wk old rooster keeps trying to mate with one particular 13 wk old hen. This might be a stupid question, but is the 18 wk old rooster hurting her? I haven't seen her submit to him or the 13 wk old rooster. But the poor thing is missing a lot of head/neck feather now. The other part of this question is WHY when the rooster is trying to mate with her and she is desperately trying to get away do the older hens come and peck at her? Two or three of the older ones do this. Are they all trying to get her to submit? They don't do this to any of the other 13 wk olds. Just this girl and wouldn't you know it, she's my favorite. Maybe when I put the next group in with them, they will find someone else to pick on.