I have a hen that will be a year old this in a month. She started to lose feathers on her back in late Nov. I figured she was molting being that my birds are free from disease and pests, well nourished, and very free range. She has gotten progressively more naked and shows no signs of feather regrowth, She has also continued to lay eggs. All my chickens laid through the winter. Why is my chicken not growing her feathers back? Bad genetics? She did come from Tractor Supply.