Thank you! I was trying to surf Google images to figure it out. I was guessing 20 weeks. One of the Wyandotts looks older indeed and the other Wyandotte looks to be the youngest and at the bottom of the pecking order. I'm certain she is the one that is 15 weeks. The white Ameraucana has her classic face feathers but the brown Ameraucana doesn't. It has been quite the adventure starting backyard chickens and I'm learning more every day. Thanks for the help!