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] Strigiformes Wagler, 1830 - owls
         Family Strigidae Vigors, 1825 - owls
           Subfamily Surniinae del Hoyo et al., 2014
             Genus Aegolius Kaup, 1829
               1 Aegolius funereus (C. Linnaeus, 1758) - boreal owl
               2 Aegolius acadicus (J.F. Gmelin, 1788) - saw-whet owl
               3 Aegolius ridgwayi (Alfaro, 1905)
               4 Aegolius harrisii (Cassin, 1849) - buff-fronted owl