My girl Ozzy has black on the tips of her comb. She has had this for a long time, before the cold weather. No one else has had this (5 other hens) until recently - now one other hen has the same thing. Don't think it's frostbite, because it's been around since before the cold weather. Thought is was dirt originally. Here is a pic: Sorry it's sideways - still trying to figure out the new phone So what is this? Thanks, all those who have gone before!