Fledgling Cardinal 
Hatchlings: Young birds who've broken out of the egg but whose eyes haven't opened.
Nestlings:  Young birds with open eyes still in the nest.
Fledgling:  A young bird that has left the nest; is fully feathered, with a short tail and wings; 
and is able to walk, hop, or flap its wings, but is still being cared for by the parents.