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.
The best way to celebrate Chicken Dance Day is by getting out there and doing the Chicken Dance! Itâs quite simple, and it all starts with making a beak with your hands, and âsquawkâ them four times in beat with the music, then you make wings as described earlier, and flap them four times in time with the music.