Hi, I posted elsewhere too, but it looks like our rooster got a few small spots of frostbite last night, despite clean bedding, no water in the coop at night, no drafts, etc. It was about negative five outside. We put vaseline on his comb and wattles, but still too cold for him. The hens and guinea hens seem just fine by the way, but we went and got Mr. Big Guy a small space heater for tonight, as it's supposed to be even colder out. It's up to 23 inside the coop, so hope that preserves his studly good looks (that's what his girls say at least).
I read a lot of older posts from people up in Canada who swear by no heat, and we have gone with that. But, I hate to see our great rooster lose his comb if I can help him out a bit. We plan to turn the heater off when the temp outside goes back up into the teens. We ended up getting a small forced air heater than automatically shuts off when tipped over, so no worries about fire.
Stay warm!