I have 2 sets of birds (3 in each) that I ordered as chicks and they are 4-5 weeks apart. The older group is 9 weeks old and one is a barred rock rooster. He is twice as big as the leghorn who is the same age. I am going away next week and planned to have all my birds in the coop by the time I left. I just put the younger group in yesterday and I know I should expect some pecking to go on, but is the rooster big enough to hurt them? He is a little over half their size. They have just been cuddled in a corner together and he pecks at them when they try to eat.