I have 2 roosters and 11 hens. I keep the hens in our main coop and pen, and the roosters are in a small coop with a young hen near the coop with the hens. Whenever the hens and roosters are let out to mingle, the roosters go off and attack the hens. I know its for mating because I have seen the roosters mount, but they are being so mean to our ameraucanas, black australorps, and one barred rock. One of the ameraucanas just layed on the ground after both roosters got her and when I picked her up, she was trembling and limp. I end up separating 3 or 4 chickens into a separate pen to keep the peace. What can I do to stop the roosters from going after the girls?