I have two hens and the smaller one, Crown Royal, is suffering in the winter cold. She is still eating but she's somewhat listless. She's a lot skinnier than in the summer time, though. I have them in a coop two feet off the ground with about three inches of wood shavings. The structure "floats" on the floor base (for removal / cleaning) and there is a vent. There is no ice or excessive condensation on the windows, so I don't think moisture is an issue. Anyway, I thought Crownie was suffering from frostbite-- the feathers on top of her head looked frost-covered, although the wattle was fine. I brought her inside last night and I see now that it's just white-coloured short feathers. She's apparently lost head feathers. She's not losing feathers excessively in other areas. I'm giving them both extra high-calorie foods, but Crownie isn't responding. Fluffy is doing fine, however. Any advice?