I have some chicks on order from our local farm/feed store. They will not arrive unti the first week of April. The store will have some chicks in earlier on a first come first serve basis in Mid-March. If I get chicks at different times, I know I have to separate them since they will have different temperature needs. Will there be a problem introducing the younger pullets (at 6 weeks old) to the ones that will be three weeks older and already in the coop? Should I be patient and just wait and get them all at one time instead? This is our second time around raising chickens. We did it four years ago and enjoyed it so we decided to start again. The older chicks would be Buff Orpingtons and Auraucans and the younger ones would be White Rocks and Black Austraslorps.
Not saying it is normal, but I introduced my week olds to my 6 week Buff Orps and they were just fine. I keep the younger chicks outside just during the day cause it's so warm, and inside at night. Even unsupervised, they just leave each other alone. But Buff Orps are really docile birds. I say, see how things go and be there to separate them if necessary. Good luck!
My Barred Rocks are about 2 months older than My Rhode Island Reds and I kept them separated but together if that makes sense. I had plastic chicken wire dividing my coop until they got to the same size and they are fine together. See how yours do and then you'll know if you need to make some kind of divide or not. Good luck