I have 3 hens all with black combs and one with black wattles too. It started with one hen and seemed to spread to the others. I thought it was frost bite but now am not so sure. I did have Avia Charge 2000 in their water but I don't think that makes a difference. Yesterday it was well above freezing here on Long Island and I discovered to my dismay that my favorite hen has it too. I have been putting antibotic cream on them daily.