I have (2) 14 weeks old pullets in a smaller coop next my my (6) 30 something week old hens. I am thinking about starting sessions where I put the young chickens in the big coop to see how it plays out but my only concern is the big hens will attack the little ones before I have time to intervene. Will I have time to stop them?
How big is your coop? How big is your run? Have you provided them with plenty of places to hide away from the older birds? IF your coop and run are big enough (at least 4 s.f. in the coop and 10 s.f. in the run/bird) and you have extra feeding stations, and places for the youngsters to flee to, go ahead and combine them. However, be prepared for some bullying. That's what chickens do. You can't stop it, and indeed if you hang around and worry over it, you will make it worse. If you ever let them out to free range, that's the perfect time to work on integration. Also, be sure you give them some good treats to work on when you integrate. They can't beat up their flock mates if they are busy eating.
Wait til the babies are nearly as large as the flock they will be joining. before combining the flocks, separate them with chicken wire so they can see each other but not get to each other. You can do this in the run or the coop. After a few days, start sprinkling scratch near the wire separation so they are feeding very close to each other. when they start ignoring each other, start to prep the coop and run you are moving them to. There should be sufficient room as lazy gardner said above. Make sure there are areas to hide in both the run and the coop- you can put boxes, bins, hay bales, etc to create areas out of sight. Multiple heights help as well. The older flock may not allow the younger ones to eat or drink, so provide multiple waterers and feeders. One way is to let the two babies explore the run before you let the older ones out - give them a couple hours to explore and get familiar with it (this is after you have added some obstacles to hide behind). Then, pick up the babies, let the flock out, and shut the coop up, leaving the babies to explore inside for a couple hours. THis should be after they have had a week or so of being in sight of the older chickens, and hopefully right next to each other just separated wtih chicken wire. Then open the coop so the babies can venture out, and be sure to watch. Expect pecking. THe little ones will run away, that is fine. Keep a handful of scratch, and if there is more than mild pecking, distract with the scratch. You will need to supervise at roost time as well for a few days. If they are sufficiently used to each other because you allowed plenty of time to become aclimated by side-by-side living separated just by wire, it will go much easier . If you cut corners and just toss them together, you risk injury (yes, it happens, blood can be drawn) If you are right there, you will be able to rescue the babies if needed, but grit your teeth and try not to intervene unless you have to. Again, get them used to each other before combining them.
At 14 weeks, they're almost large enough that they should be able to hold their own. As my two friends above have pointed out, a period where the original flock can see and become acquainted with the new pullets would be helpful before letting them mingle. In the future, consider brooding your new chicks alongside the adult flock so they will be accepted much earlier. You can read about reasons for doing this in my second article linked below.
Our combined flock still has their squabbles and hissy fits and it's been months now. I think they're always going to have the "us and them" mentality! No one gets seriously hurt so I just leave them to it.
