We took in 20 battery hens. They have been doing so well and are really starting to act like chickens do! A lot of them have bad feather loss. Then last night I noticed some black circular spots on the chickens combs. Also some have black spots on their back's where feathers are missing. None of the spots look raised and they appear to be old? Some of the ones with feather loss have bright red skin though. I'm wondering if they are nearing the end of their infection? They had always been in battery cages so I don't think it would be frostbite. Or could it be some sort of scar from a previous infection? I'll try to get some pictures of the black marks to add in right now.