So I have four pullets around two and a half months old and three chicks that are around three weeks old. The littles are fully feathered out now (and it's very hot where I live) so late last week I decided it was time for their brooder pen to go outside. I put it in the chicken run on the opposite side of a fencing panel from where the big chickens are, so that the big chickens and little chickens could see each other and not be able to interact. That seemed to go pretty well for two days, so over the weekend during the day while I was home, I let the little chicks range with the big chickens and other than a few pecks from my most dominant/aggressive hen (a black EE/Orp pullet named Drogon), they mostly left the little chicks alone and each group kept to itself. I got cocky, and decided yesterday to leave the chicks out all day in the run with the big chickens since everyone seemed to be getting along and I'm really tired of dealing with the brooder pen since the chicks are off heat now. But I got a call around lunch from my dad saying the black EE pullet was chasing the chicks around trying to peck them and was especially attacking my little brown bielefelder chick. I rushed home and re-segregated everybody, and have had no further problems. There were no injuries, thankfully, but I would have been devastated if my little bielefelder chick was maimed or killed because it's the only chick I've kept that I hatched myself. How long should I continue to leave the brooder pen next to the run fence for gradual "look don't touch" integration? And if I wait, say, two weeks and reintegrate and my black pullet is still being a jerk, is the best option to put HER in a crate for 2-3 days and see if her attitude straightens out? So far she is the only chicken who has shown any aggression towards the chicks. The other pullets seem content to ignore them since there is plenty of food and water and treats to go around.