We usually see a lot of threads on BYC in late Dec, Jan, and Feb about frostbite from Canada, Minnesota, and other up north places. With large combs, it is usually inevitable that you will see some frostbite on large combs. The real danger is on their feet and legs. Making sure the bedding is dry and kept fresh is helpful. Open waterers can allow frostbite on wattles and if accidentally stepped in by feet.I see I will research it. We live in an area the coldest it has been here since we've lived her for two winters was -4 F but mostly the cold weather is 0 in January early February. We have two roosters with really big combs. I mean we don't live in Canada cold or anything, but this will be my first winter with a flock.
