This is our first winter with our girls. We have decided not to heat our coop but there has been a cold spell the past week. Last night even got to 15 below. We have 6 hens in small coop. Draft free and a small wire window we open during the day for ventilation. We have put straw bales around the exterior of the coop and run for wind blockage and some extra insulation. 3 of our girls...2 Bo's and a leghorn are getting frostbite on their combs. The leghorns frostbite is especially alarming. What can we so for them? Anything? Do we need to heat or just let the frostbite run it's course? I don't want to lose any girls this winter!