The Chahinkapa Zoo in Wahpeton, has two displays with Bald Eagles.
"A two year old bald eagle has some white mottling on the chest, there is more yellow developing on the bill and the underside of the wings show extensive white feathers. The top of the head is a more golden brown than a one year old eagle exhibits and the eyes are a lighter shade of brown."
-http://www.onthewingphotography.com/wings/2011/02/16/bald-eagles-one-to-five-years-old/