They're all about 4-6 weeks old. We have 6 of them. They're getting their feathers very quickly and are getting large! It has been in the 40s at night and in the 50s-70s during the day. Can they go outside? I could put the heat lamp in their coop no problem, but can they go outside as they please if they can go back in the coop for warmth? Or is the weather too cold for them to be away from the lamp at all times? Thanks.