Here in RI is is about -2 degrees. I have three Black Star hens. They have a small draft free well constructed coop with TONS of hay to nest in inside of it. There is a small tiny light in there but it gives off no heat. The water in the coop is constanatly freezing so twice a day I change it with warm water. Obviosly, the temperature in the coop is below freezing temperatures. What kills me is that rather than being in the draft free coop, the three of them keep leaving to run around the freezing snow covered yard. I put vaseline on there large combs yesterday night, but it seems it came off since this morning. Should I be concerned? How much cold can they take?! I am very nervous about them. What can I do!?