Chicken molting is losing feathers at about 16 to 18 months of age or a multiple of that. It is obvious when your chickens are going through a molt because many of their feathers fall out and the egg production stops. The chickens look really bad when their neck feathers fall out. She is missing neck and tail feathers. It will be interesting to see how much the egg production decreased after this molt. A good reason to have different age chickens is to always have some producing eggs.