Whether they have any extant function or not, they have lost their former function and in that sense they do fit the definition of vestigiality. Vestigial structures are often called vestigial organs, although many of them are not actually organs.
There are quite a few birds famous for doing ritualized mating dances, so I would only list 5: The Red Capped Manakin, The Black-footed albatross, The Western and Clark's grebe, The Superb bird of Paradise, & The Victoria's riflebird.
Native American Pueblo Indians would pay homage to the Feathered Sun which is a symbol of the cosmos and the center of existence. Another symbol meaning of feathers also revolves around prayer, and the Pueblo use feather sticks as they dance in prayer for rain during solstice rituals.s a Celtic symbol meaning, the feather was worn by Druids in the form of ornate feathered robes. Celtic Druids donned these robes in ceremonies to invoke the sky gods and gain knowledge of the celestial realm.