Phylum Chordata Bateson, 1885 - chordates
   Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
     Subclass Neornithes Gadow, 1893 see Clade Neornithes Gadow, 1893
       Superorder Neognathae Pycraft, 1900 see Cohort Neognathae Pycraft, 1900
         Order Anseriformes Wagler, 1831 - waterfowl and screamers
           Family Anatidae Vigors, 1825 - ducks, geese, swans
             Subfamily Anserinae Vigors, 1825 - geese
               Genus Cygnus Bechstein, 1803 - mute swan
                 1 Cygnus olor (Gmelin, 1789) - mute swan
                 2 Cygnus atratus (Latham, 1790) - black swan
                 3 Cygnus melanocoryphus (Molina, 1782) see Cygnus melancoryphus (Molina, 1782)
                 4 Cygnus cygnus (Linnaeus, 1758) - whooper swan
                 5 Cygnus buccinator Richardson, 1831 - trumpeter swan
                 6 Cygnus columbianus (Ord, 1815) - tundra swan