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.
Ghost DanceEdit. The Ghost Dance was a Native American religious movement that occurred in the late 1800s, often practiced by the Sioux Natives. It consisted of a circle dance, invented by the Native leader Wovoka, or better known by his white name, Jack Wilson.