For frostbite I would highly recommend using the Homeopathic remedy Agaricus Muscarius (AGAR) in a potency 30c. I've used it several times on my girls and especially my F.B.C. Maran Roo (and myself!). I've had the "fingers" on my roo's comb start out visibly black and have gotten it to heal completely. Your local Health Food Store may carry it or try online at abchomeopathy.com. (it's not a prescription) Take a plastic throw away container or cup, add water and put 1 pellet in, let dissolve. I give a dose to them as needed or put in a bowl and let them dose themselves (esp if not tame). I dose mine a minimum of 2 times a day (or more esp. if really bad or extremely low temps). I continue to dose them til it's gone and then I give an extra dose to be sure. If there's one with frostbite I will offer it to it, if it doesn't drink it freely, then I will hold it and stick it's beak into the remedy water til it drinks some. If there's many I may hold & dose those worse off and put down the bowl for the rest. FYI: Make sure to have regular fresh water available if you decide to provide a bowl of Agaricus. Do not use a container that you will use for other food uses- if you do you will be administering the remedy to yourself. (Even if you wash it) If you accidentally spill it on yourself- you just got a dose of the remedy. (I have been accidentally dosed by birds that shake their head and splatter remedy water all over me) Not a huge deal just better if it doesn't happen. You can overdose them so be careful and aware of the animal your treating. If animal starts getting better and then gets worse it's probably overdosed. Stop remedy, watch it get better and ONLY treat again WHEN it gets worse again. I write on the plastic container with a sharpie marker the remedy that It's for and reuse it. A pipet (pipette) could also be used- squeeze a drop onto beak til it drinks or open beak & drop some in.