CLASS Aves: fusiform body, fore limbs generally modified for flight and hind limbs with four digits for settling, walking or swimming. Body covered with feathers and legs covered with scales. Skeleton with pneumatic cavities. Jaws lacking teeth, covered with horny bills. Endotherms (warm-blooded) and oviparous.

SUPERORDER Neognathae: flying (or swimming) birds, keeled sternum supporting flight muscles.

ORDER Anseriformes: waterfowl and screamers. 2 families and 151 species.

FAMILY Anatidae: waterfowl (ducks, geese, swans).
FAMILY Anhimidae: screamers.

ORDER Apodiformes: swifts and hummingbirds. 3 families and 400 species.

FAMILY Apodidae: swifts.
FAMILY Hemiprocnidae: tree swifts.
FAMILY Trochilidae: hummingbirds.

ORDER Caprimulgiformes: nightjars and frogmouths. 5 families and 100 species.

FAMILY Aegothelidae: nightjars.
FAMILY Caprimulgidae: nightjars.
FAMILY Nyctibiidae: potoos.
FAMILY Podargidae: frogmouths.
FAMILY Steatornithidae: oilbird.

ORDER Charadriiformes: shore birds, auks and gulls. 15 families and 292 species.

FAMILY Alcidae: auks, razorbill, murrelet, and puffins.
FAMILY Burhinidae: stone curlews.
FAMILY Charadriidae: plovers.
FAMILY Chyoninidae: Antarctic doves.
FAMILY Dromadidae: crab-plover.
FAMILY Glareolidae: pratincoles.
FAMILY Haematopodidae: oystercatchers.
FAMILY Ibidorhynchidae: ibis bills.
FAMILY Jacanidae: jacanas.
FAMILY Laridae: gulls and terns.
FAMILY Recurvirostridae: stilts and avocets.
FAMILY Rostratulidae: painted snipes.
FAMILY Scolopacidae: sandpipers, snipes, turnstones, woodcocks, curlews and pharalopes.
FAMILY Stercorariidae: skuas.
FAMILY Tinocoridae: seed snipes.

ORDER Ciconiiformes: herons and storks. 5 families and 110 species.

FAMILY Ardeidae: herons, night herons and bitterns.
FAMILY Balaenicipitidae: shoebill.
FAMILY Ciconiidae: storks and marabou storks.
FAMILY Threskiornithidae: ibises and spoonbills.
FAMILY Scopidae: hamerkop.

ORDER Coliiformes: mousebirds. 1 family and 6 species.

FAMILY Coliidae: mousebirds.

ORDER Columbiformes: pigeons and doves. 2 families and 320 species.

FAMILY Columbidae: pigeons and doves.
FAMILY Pteroclidae: sandgrouse.

ORDER Coraciiformes: kingfishers. 8 families and 200 species.

FAMILY Alcedinidae: kingfishers and kookaburras.
FAMILY Bucerotidae: hornbills.
FAMILY Coraciidae: rollers.
FAMILY Meropidae: bee-eaters.
FAMILY Momotidae: motmots.
FAMILY Phaeniculidae: wood-hoopoes.
FAMILY Todidae: todus.
FAMILY Upupidae: hoopoe.

ORDER Cuculiformes: cuckoos. 5 families and 130 species.

FAMILY Centropidae: coucals.
FAMILY Coccyzidae: malkohas and Coccyzus cuckoos.
FAMILY Crotophagidae: anis and guiras.
FAMILY Cuculidae: cuckoos and couas.
FAMILY Neomorphidae: roadrunners.

ORDER Falconiformes: diurnal raptors. 4 families and 290 species.

FAMILY Accipitridae: eagles, kites, goshawks, harriers, buzzards, Old World vultures.
FAMILY Catartidae: New World vultures, condors.
FAMILY Falconidae: falcons, kestrels and caracaras.
FAMILY Sagittariidae: secretary bird.

ORDER Galliformes: fowl and game birds. 4 families.

FAMILY Cracidae: guans, chachalacas, curassows.
FAMILY Megapodiidae: brush turkeys, megapodes.
FAMILY Opistocomidae: hoatzin.
FAMILY Phasianidae: turkeys, quails, bobwhites, ptarmigans, grouse, pheasant, francolins, peacocks, Guinea fowls, capercaillies.

ORDER Gaviiformes: loons. 1 family and 5 species.

FAMILY Gaviidae: loons.

ORDER Gruiformes: cranes. 12 families and 220 species.

FAMILY Aramidae: limpkin.
FAMILY Cariamidae: seriemas.
FAMILY Eurypygidae: sunbitterns.
FAMILY Gruidae: cranes.
FAMILY Heliornithidae: sungrebes.
FAMILY Mesitornithidae: roatelos.
FAMILY Otididae: bustards.
FAMILY Pedionomidae: Australian buttonquails.
FAMILY Psophiidae: trumpeters.
FAMILY Rallidae: rails.
FAMILY Rhynochetidae: kagu.
FAMILY Turnicidae: buttonquails.

ORDER Musophagiformes: turacos. 1 family and 20 species.

FAMILY Musophagidae: turacos.

ORDER Passeriformes: songbirds or perching birds. 73 families and some 5,000 species.

FAMILY Acanthisittidae: New Zealand wrens.
FAMILY Eurylaimidae: broadbills.
FAMILY Phylepitidae: asitis and false sunbirds.
FAMILY Pittidae: pittas.
FAMILY Dendrocolaptidae: woodcreepers.
FAMILY Furnariidae: furnarians, canasteros, woodcreepers.
FAMILY Formicariidae: antpittas.
FAMILY Rhinocryptidae: tapaculos.
FAMILY Acanthizidae: Australian whitethroats.
FAMILY Aegithalidae: long-tailed tits.
FAMILY Alaudidae: larks and sparrow-larks.
FAMILY Artamidae: Australasian wood swallows.
FAMILY Atrichornithidae: Australian bush birds.
FAMILY Bombycillidae: waxwings.
FAMILY Callaeidae: New Zealand caruncled crows.
FAMILY Campephagidae: cuckoo-shrikes.
FAMILY Certhiidae: creepers.
FAMILY Cinclidae: dippers.
FAMILY Climacteridae: Australian creepers.
FAMILY Corvidae: crows, ravens, magpies, jays, jackdaws, nutcrackers.
FAMILY Cracticidae: Australian magpies.
FAMILY Dicaeidae: flowerpeckers.
FAMILY Dicruridae: drongos.
FAMILY Drepanididae: drepanids.
FAMILY Dulidae: palm birds.
FAMILY Emberizidae: buntings, New World sparrows, cardinals, grosbeaks, towhees, tanagers, warblers, New World finches.
FAMILY Epthianuridae: Australian chatterers.
FAMILY Estrildidae: munias, firefinches, pytilias.
FAMILY Fringillidae: chaffinches and carduelins (canaries, goldfinches, greenfinches, redpolls, siskins, crossbills, bullfinches).
FAMILY Grallinidae: Australasian choughs.
FAMILY Hirundinidae: swallows, house martins.
FAMILY Hypocolidae: hypocolius.
FAMILY Icteridae: blackbirds.
FAMILY Irenidae: yoras.
FAMILY Laniidae: shrikes, fiscals, bush-shrikes and helmet-shrikes.
FAMILY Maluridae: Australian wrens.
FAMILY Meliphagidae: honeyeaters, miners.
FAMILY Menuridae: lyrebirds.
FAMILY Mimidae: mockingbirds, tremblers, catbirds.
FAMILY Monarchidae: monarchs.
FAMILY Motacillidae: wagtails, longclaws, pipits.
FAMILY Muscicapidae: Old World flycatchers.
FAMILY Nectariniidae: sunbirds.
FAMILY Oriolidae: orioles.
FAMILY Orthonychidae: logrunners.
FAMILY Pachycephalidae: whistlers.
FAMILY Paradisaeidae: paradise birds.
FAMILY Paridae: tits, titmice, chickadees, great tits.
FAMILY Parulidae: American wood warblers.
FAMILY Passeridae: Old World sparrows.
FAMILY Petroicidae: Australasian robins.
FAMILY Ploceidae: weavers, buffalo-weavers, sparrow-weavers, queleas, widowbirds, cuckoo finches.
FAMILY Prunellidae: prunellids.
FAMILY Ptilogonatidae: phainopeplas.
FAMILY Ptilonorhynchidae: bowerbirds.
FAMILY Pycnonotidae: bulbuls.
FAMILY Remizidae: penduline tits.
FAMILY Rhabdornithidae: Philippine creepers.
FAMILY Rhipiduridae: fan-tailed flycatchers.
FAMILY Sittidae: nuthatches.
FAMILY Sturnidae: starlings, oxpeckers, mynas.
FAMILY Sylviidae: Old World warblers, cisticolas.
FAMILY Timaliidae: chatterers, babblers.
FAMILY Troglodytidae: wrens.
FAMILY Turdidae: thrushes, blackbird, robins, nightingales, solitaires.
FAMILY Vangidae: vangas.
FAMILY Vireonidae: vireos, peppershrikes, greenlets.
FAMILY Zosteropidae: white-eyes.
FAMILY Cotingidae: cotingas.
FAMILY Oxyruncidae: oxyruncus.
FAMILY Phytotomidae: leafcutters.
FAMILY Pipridae: manakins.
FAMILY Tyrannidae: flycatchers, kingbirds.

ORDER Pelecaniformes: pelicans. 5 families and 56 species.

FAMILY Fregatidae: frigatebirds.
FAMILY Pelecanidae: pelicans.
FAMILY Phaethontidae: tropicbirds.
FAMILY Phalacrocoracidae: cormorants and anhingas.
FAMILY Sulidae: gannets and boobies.

ORDER Phoenicopteriformes: flamingoes. 1 family and 5 species.

FAMILY Phoenicopteridae: flamingoes.

ORDER Piciformes: woodpeckers and barbets. 6 families and 378 species.

FAMILY Buconidae: bucos.
FAMILY Capitonidae: barbets.
FAMILY Galbulidae: jacamars.
FAMILY Indicatoridae: indicators.
FAMILY Picidae: woodpeckers.
FAMILY Ramphastidae: toucans, aracaris.

ORDER Podicipediformes: grebes. 1 family and 19 species.

FAMILY Podicipedidae: grebes.

ORDER Procellariiformes: albatrosses and fulmars. 4 families and 92 species.

FAMILY Diomedeidae: albatrosses.
FAMILY Hydrobatidae: storm petrels.
FAMILY Pelecanoididae: diving petrels.
FAMILY Procellariidae: shearwaters and petrels.

ORDER Psittaciformes: parrots. 1 family and 330 species.

FAMILY Psittacidae: cockatoos, lories, parrots, parakeets, macaws.

ORDER Sphenisciformes: penguins. 1 family and 17 species.

FAMILY Spheniscidae: penguins.

ORDER Strigiformes: owls. 2 families and 162 species.

FAMILY Strigidae: owls.
FAMILY Tytonidae: barn owls.

ORDER Trogoniformes: trogons. 1 family and 37 species.

FAMILY Trogonidae: trogons, quetzal.

SUPERORDER Palaeognathae: ratites and tinamous. Non-flying birds, sternum not keeled.

ORDER Apterygiformes: kiwis. 1 family and 3 species.

FAMILY Apterygidae: kiwis.

ORDER Casuariiformes: cassowaries and emus. 2 families and 4 species.

FAMILY Casuariidae: cassowaries.
FAMILY Dromaiidae: emu.

ORDER Rheiformes: rheas. 1 family and 2 species.

FAMILY Rheidae: rheas.

ORDER Struthioniformes: ostriches. 1 family and 1 species.

FAMILY Struthionidae: ostrich.

ORDER Tinamiformes: tinamous. 1 family and 45 species.

FAMILY Tinamidae: tinamous.