We have 4 Ameraucana hens that are all about 4-5 months old. They recently started laying. Earlier this week we noticed that one of our chickens, Billie, was developing a bald spot directly under her beak. The rest of her feathers are full and fluffy. The skin has never looked red or bloody. We haven't noticed any one picking on her or her bullying anyone else. None of the other birds seem to be developing any bald spots. Is this just a pecking behavior by the other birds or some sort of illness?