I have 4 girls, one light Brahma. the last few days I have noticed her feathers in the coop, the run and the free range area. Her head feathers appear to be thinning out. I have not seen any other girl pecking at her, but then I am not with them 24/7. All my hens are 10 months old. Could she be molting? Also some of her white feathers are yellowing. Any ideas?