This is my second year with chickens so they are going through their first molting. The problem is they are molting now, in December. I live in Maine and it's getting down to the single digits at night. Is there something I should do to help them keep warm as they shed their down feathers? I don't have a lightbulb in my coop and do not wish to add one due to fire hazard. I have been giving scratch at night to try and help. Will they survive?