I got a batch of Australorp chicks a few weeks ago, and the farmer threw in a Barred Rock for free. She is turning out to be my favorite! She's the most feisty but still docile enough; she's the fastest chick of the bunch, usually in the back of the flock but sometimes darts to the front for a quick treat. I got some grown hens the other day (some more Australorps, some Orpingtons, and some Plymouth Rocks) and mixed them with my now-6-week-old chicks, who have been in the coop outside for a week now. Went outside to put the chicks in a cardboard box for the night since tonight will be significantly colder than the last week, and found one of the new Plymouth Rock pullets snuggled up on the floor with the chicks! I left them like that and I'm sure they'll be fine (it's supposed to get down to 39Fahrenheit).