Is this an adult or a juvenile?

Photo Eva Szyszkoski, ICF

Eva says, "Chick 904 looks a lot like an adult. She has very little brown plumage left. Sometimes we mistake her for an adult when we are in the blind until we get a close look at either her leg bands or her head. She may have a lot of white plumage, but she doesn't have the red head patch of an adult quite yet."