weve been getting frost over past few nights and the temperatures were down to freezing. one of my smaller sized hens comb, is looking half black.. she is a black and white hen, however im worried that its frost bite instead of her normal colour of the skin. she is the only out of 5 chickens that ive noticed changed in the comb colour... I have weather proofed the coop and made sure they are set for winter. is there anything else I should be doing to prepare my hens for winter...?