Question is how much fighting is acceptable between flocks? I have 5 Rhode Island Reds 13 weeks old and 5 Plymouth Rocks 9 weeks old. I have had the younger ones next to the run for two weeks now and they seemed to be not to interested in each other. Yesterday we just let two of the older ones out with 5 of the younger ones and the two older ones aggressively kept going after the younger ones trying to pin them down. So we just put the younger ones back in their tractor next to the older ones run. We have a 6x8 coop attached to a 8 x 12 run and then an additional 8x12 open space to start them to getting use to free ranging. Two sources of food and water. The physical introduction was done about two hours before roosting time. I’m just trying to prevent the younger ones from getting seriously hurt. Any advise would be great.