Just this morning I noticed that our largest rooster has some black spots on his comb. The spots are quite black, round, but not raised. They are not on the tips of the comb so I don't think it's frostbite. I did dip below freezing last night but I imagine it has to be colder than that for frostbite to occur? Our birds free range all day and at night they sleep in our chicken barn, which is an old roomy structure with straw and shavings on the floor as deep litter. It's normally quite dry, but some rain did come in through a broken window earlier in the week and get the litter damp. Is it possible this has created some kind of infection? I just went and inspected and everything seems dry enough now. There is a window in the roof of the barn which is open 24 hours a day and the door is open all day too. Our two Rhode Island Red hens also seem to have some small black spots starting on their combs. So I'm pretty concerned. I will try to get some pictures when I get the chance. In the meantime though, does anyone know what might cause the black spots?