Neornithes Gadow, 1893 - living birds
   Neognathae Pycraft 1900 see Cohort Neognathae Pycraft, 1900
     Neoaves Sibley et al. 1988 see Subcohort Neoaves Sibley et al., 1988
       [Order] Ciconiiformes Bonaparte, 1854
         Family Ardeidae Leach, 1820 - herons, bitterns and egrets
           Subfamily Botaurinae Bock, 1956
             Genus Ixobrychus Billberg, 1828
               Ixobrychus exilis (Gmelin, 1789) - least bittern
                 1 Ixobrychus exilis exilis (Gmelin, 1789)
                 2 Ixobrychus exilis pullus van Rossem, 1930
                 3 Ixobrychus exilis erythromelas (Vieillot, 1817)
                 4 Ixobrychus exilis limoncochae Norton, 1965
                 5 Ixobrychus exilis bogotensis Chapman, 1914
                 6 Ixobrychus exilis peruvianus Bond, 1955