I have a flock of six that include 2 Australorps and one of them is at the top of pecking order. They are all 18 weeks. My flock only roost during the day and huddle together at night in the coop at the top of steps on the landing. My guess is it to cold to be on a roost at the moment or maybe they will when they are older. Or I need a larger roost for sleep and don't feel safe enough on the one that's in the coop.