ok question guys. When do I go about introducing my chicks the the flock? And how? I only have 1 coop. So I can't pen the up side by side. Other then that my chickens free roam. We just put them in the coop at night. The chicks are pretty well feathered. It does dip in the 40s at night. So not sure if the temperatures are ready yet. When we did take the chicks out a while back to walk around, our big brahma rooster came and picked them up by the head and was running off with them. Not sure if he was trying to breed them? Or being agressive of protective, but we got them away quick! Our litle cochin rooster was the most attentive to them. He was herding them around. And our hen doesn't care she is just up the brahma roosters bum. Lol
It doesn't sound like your chicks are ready yet. Both for the night time temps yet and maturity level. Your Brahma rooster was being aggressive because the new chicks were foreign. It is common for established chickens to attack new chickens, even if they are the same size or age.
On the rare occasion that I have had to seperate a hen for whatever reason (injury or hatching eggs) whenever they are re-introduced the flock acts like she is an intruder they have never seen and attacks.
Here is how I introduce new birds/older chicks no matter age or size.
Once I feel chicks are old enough and know how to run for cover, I will pen them next to the existing birds for several weeks first. If that can't be done, enclose them in a safe temporary little pen or rabbit cage within the chicken yard or coop or area.
This allows the existing flock to get used to seeing them and to learn that they are not a threat. Most chickens will not accept new chickens, even though they are still chickens, without an adjustment period.
(Same with ducks, turkeys, guineas, or whatever new bird.)
After everyone seems to ingnore everyone else, I wait until it is darm and all the birds have roosted for the night, then slip the new birds onto the roosts with the other birds. When everyone "wakes up" in the morning the new birds are there as if they have always been there.
However, close supervision is still needed as the hierarchy has been disrupted and much squabbling will ensue, sometimes for days. Make sure the new ckicks have a place where they can get away from the bigger chickens