We have a week old mixed flock in the brooder and I've noticed when they settle down to sleep they seem to pair off in twos by breed. We picked them up at the hatchery when they were 1 day old and we've noticed this since the first evening. Is this common that they recognize their own breed? We have two each of a handful of breeds with the exception of the Barred Rocks because they threw an extra one in for free. They will mix and mingle, eat and play as a group but almost always pair back up when it's time to settle down for sleep. Our local chicken friends think we're crazy but we see it with our own four eyes lol.