I searched for information on frostbite and black on combs but didn't come up with anything conclusive. We had our first cold day with wind. Last night before bed I went to check on birds I noticed roo's comb becoming dark almost black on tips. This morning his color is back to normal. Was this the begining of frost bite? Dumb cluck could have gone into the coop where there is shelter and warmth but he decided to hang outside all day. This is only the begining of our cold season!