Birds are divided into eight main visual categories: (1) swimmers—ducks and ducklike birds, (2) aerialists—gulls and gull-like birds, (3) long-legged waders—herons and cranes, (4) smaller waders—plover and sandpipers, (5) fowllike birds—grouse and quail, (6) birds of prey—hawks, eagles, and owls, (7) passerine (perching) birds, and (8) nonpasserine land birds.—A Field Guide to the Birds East of the Rockies, by Roger Tory Peterson.
Voëls word in agt waarneembare kategorieë verdeel: (1) swemvoëls—eende en eendagtige voëls, (2) seevoëls—meeue en meeu-agtige voëls, (3) waadvoëls met lang bene—reiers en kraanvoëls, (4) kleiner waadvoëls—kiewiete en strandlopers, (5) hoenderagtige voëls—korhoenders en kwartels, (6) roofvoëls—valke, arende en uile, (7) boomvoëls en (8) grondvoëls.—A Field Guide to the Birds East of the Rockies, deur Roger Tory Peterson.jw2019 jw2019