Hello, we are totally new to the chickens community, got 4 Redstars about a year ago, They are doing fine, treated as pets, fed Purina organic food for layers, also get daily treats in the form of grapes, non-fat plain yogurt etc They do have enough space in the coop and in the runner. Over the weekends we also allow them to just walk around, so they are partially free range. The problem is with one of them. She lost some of her feathers in the front several months ago, but lately she lost more and it's happening on her neck as well. Also the naked skin looks red and irritated. We were trying to see if there are some creatures/mites biting her - nothing that we can see. Other chicken has some feathers loss under her wings, and that happened several months ago. They behave normal and continue to lay eggs. But there is definitely some problem. Can somebody please help?