I have five 7 1/2 month old chickens (all girls) and four 5 1/2 month old chickens (all girls)that I have been trying to combine for over a month. They have lived side by side in seperate runs and roost in seperate coops with a shared fence for two months. I have tried to let them range together in a large fenced in area but the older ones corner a younger one and attack it. It is not a certain one. They attack all the younger ones, who run sqawking to the nearest cover. I have not seen blood shed, but they have pulled quite a few feathers. The are all about the same size except the Andalusian who is the smallest of both groups. She will stand up for herself one on one but will run if ganged up on. The #1 and #2 girls from the older group are usually the instigators of the attacks. Does anyone have suggestions on how to get these two groups to live together in relative peace? Neither group fights among themselves and all are people friendly.