I have 12 hens (4 just over a year, 8 just about 6 months) When we introduced them they were separated by chicken wire for approximately 2 months. They free range during the day and get put up at night. One of my older hens a black sexlink is extremely mean to the younger hens. I had noticed a few mean moments with the older hen, but initially thought nothing of it. Figured they were establishing pecking order. But then I noticed that one older hen was chasing the younger hens out of the coop at night.(once dark enough the younger could get in the coop. But then last week the older hen pinned one of the young hens and was pecking it. So I separated it from the rest of the flock for 4 days, and then allowed it back with the rest of the hens. Last night (after 2 days of being back) the older hen was running around the coop chasing the younger hens, she got ahold of one and had it pinned. So I once again have it separate from the others. Also i believe that as a result of this behavior the younger hens (a couple recently started laying) are not laying their eggs in the coop. I found a nest of about 8 after watching one of the younger hens walk from behind a bush. Any suggestions would be great. Thank you.