I have a question, our rooster about six months doesn't seem to let our new girls (10@4months) go outside, are they still too little? He lets the two halfies(6months) out. When the little ones try to go outside he scares them back in. What can I do to get them to go out? It is cold here but no enough for them to not be out. We have a heat lamp in the coop and in the covered outside run