I have 9 chicks about 1 month or a little over old. And I was wondering if I can keep them outside in their coop. Its inclosed and I have just a small opening for them to get in and out. But at night I'll close that opening. Do I need a light. Or is it warm enough outside I don't need it? It gets to about 55 degrees at night now. So should I keep them back inside or outside OK.