Global
IOC World Bird List - the site supplements the book "Birds of the World. Recommended English Names" by Frank Gill and Minturn Wright, 2006. Also available through Avibase.
Taxonomy in Flux by John H. Boyd III
Bird Families of the World Don Roberson
Clements Checklist - "The Clements Checklist of Birds of the World", 6th edition, 2007, by James Clements.
The Sibley/Monroe World List of Bird Names - names used by Charles Gald Sibley and Burt Leavelle Monroe, Jr. in their 1990 "Distribution and Taxonomy of Birds of the World" and its 1993 "Supplement", which were later combined to become the "Checklist".
WICE's Birdlists of the World - list of what the University of California and World Institute for Conservation and Environment (WICE) consider to be the complete lists of bird species of the world
Avibase - the Avibase database allows users to create checklists for different localities using alternative world lists, such as Sibley & Monroe 1996, Howard & Moore 3rd edition, Clements 6th edition 2008, CINFO 1993, IOC World Bird Names 2009 and others. Scientific names can be compared with common names in a number of languages.
The BirdLife checklist of the birds of the world with conservation status and taxonomic sources
WikipediaWikiProject Birds / Wikipedia - Birds / Ornithological checklists
Officiella listan över svenska namn på alla världens fågelarter Sveriges Ornitologiska Förening (Sweden)
Lista italiana degli uccelli del mondo and check also SCRICCIOLO Italian Ornithological Web Site by Alberto Masi since 1996
Zoonomen with author citations and bibliographic references for each species
Nomenclatura Vulgar das Aves em Português - uma Proposta Sérgio R. Porto, Brasil
Os Nomes Portugueses das Aves de Todo o Mundo Paulo Paixão
Aves do Mundo PT Elias
Extinct birds
List of 'extinct in the wild' birds birds only known by living members kept in captivity or as a naturalized population outside its historic range due to massive habitat loss
List of recently extinct bird species birds that have gone extinct since the year 1500 and usually were subject to scientific study while alive
List of Late Quaternary prehistoric bird species birds extinct in Late Quaternary prehistoric times and usually known from specimens not completely fossilized
List of fossil bird genera birds known only from fossils
Naturalis extinct birds Dutch National Museum of Natural History Naturalis, Leiden, The Netherlands
The Sixth Extinction and Forum Peter Maas
Holártico
Holarktis fåglar Sveriges Ornitologiska Förening (Sweden) - version 5 (2014), no longer updated
Holarctic listing A checklist of the birds of the Holarctic Region, by Richard Klim
Paleártico Ocidental
AERC TAC WP Bird List Association of European Records and Rarities Committees (AERC)
Avionary Names of birds in several languages; species from the Western Palaearctic and surrounding areas in America, Africa and Asia
La Liste des Oiseaux du Paléarctique occidental Commission de l’Avifaune Française, Centre de Recherches par le Baguage des Populations d’Oiseaux, Muséum National d'Histoire Naturelle (France)
Les oiseaux du Paléarctique occidental oiseaux.net (France)
Dutch birding bird names Dutch Birding (Netherlands)
Västpalearktislistan Sveriges Ornitologiska Förening (Sweden)
Check list del paleartico occidentale Castelli, D´Amelio & Haas (2014) (Italy)
Mapa do Paleártico Ocidental:
Portugal
Lista sistemática das aves de Portugal Continental Matias, Catry, Costa, Elias, Jara, Moore & Tomé, Anuário Ornitológico (2007) e adições e alterações Matias, Alfrey, Costa, Elias, Jara, Moore & Tomé, Anuário Ornitológico (2011) (Portugal)
França
La Liste des Oiseaux de France Commission de l’Avifaune Française, Centre de Recherches par le Baguage des Populations d’Oiseaux, Muséum National d'Histoire Naturelle (France)
Bélgica
Belgian official checklist Belgian Rare Birds Committee (Belgium)
Lijst van Belgische vogels Belgisch Avifaunistisch Homologatiecomité (Belgium)
Liste des oiseaux de Belgique Commission d'Homologation (Belgium)
Liste des oiseaux de Belgique Le monde de l'ornithologie (Belgium)
Holanda
Checklist of Dutch bird species Dutch Birding (Netherlands)
Reino Unido
British list British Ornithologists' Union (BOU) - list of birds of Great Britain (UK)
Finlândia
List of Birds from Finland BirdLife Suomen rariteettikomitea (Finland)
Alemanha
Artenliste der Vögel Deutschlands Peter H. Barthel und Andreas J. Helbig, Limicola (2005) (Germany)
Itália
Lista CISO-COI degli uccelli italianiFracasso, Baccetti & Serra, Avocetta (2009) (Italy)
Médio Oriente
Ásia Oriental
Indo-Malásia
Australásia
Bird finder - Birds in Backyards, BirdLife Australia
Afrotrópico
Neártico
cobre grande parte da América do Norte, incluindo a Groenlândia, a Florida central (mas não o sul da Florida) e as terras altas do México (mas não o resto do México e a América Central)
Check-list of North and Middle American Birds American Ornithological Society (until 2016 American Ornithologists' Union AOU) / North American Classification Committee (NACC) - list of birds of North and Central America from the North Pole to the boundary of Panama and Colombia, including the adjacent islands under the jurisdiction of the included nations; the Hawaiian Islands; Clipperton Island; Bermuda; The West Indies, including the Bahama Islands, the Greater Antilles, Leeward and Windward Islands in the Lesser Antilles (ending with Grenada); and Swan, Providencia, and San Andrés Islands in the Gulf of Mexico. Greenland is not included in the coverage of the Seventh Edition of the Check-list, although it was included in earlier editions and will be in the next edition.
ABA Area
The ABA Area (sometimes referred to as the ABA Checklist Area) is essentially North America north of Mexico. Specifically, the area encompassed is the 49 continental United States, Hawaii (since 2016), Canada, the French islands of St. Pierre et Miquelon, and adjacent waters to a distance of 200 miles from land or half the distance to a neighboring country, whichever is less. Excluded by these boundaries are Bermuda, the Bahamas and Greenland.
México
Neotrópico
cobre o leste do México, o sul da Florida, as Caraíbas, a América Central e a América do Sul
Checklist of South American Birds American Ornithological Society (until 2016 American Ornithologists' Union AOU) / South American Classification Committee (SACC)
América do Sul
Bird species of South America American Ornithological Society (until 2016 American Ornithologists' Union) / South American Classification Committee (SACC) - list of birds of : (1) continental South America and all islands within 1200 km of its shores eastward into the Atlantic and westward into the Pacific oceans (including Malpelo, the Galapagos islands, San Felix and San Ambrosio, the Juan Fernandez islands, Fernando de Noronha, Trindade, Martin Vaz, São Pedro and São Paulo Archipelago, and the Falklands/Malvinas); (2) islands in the Caribbean Sea close to South America and not covered by the AOU Checklist (including Netherlands Antilles, Trinidad and Tobago); and (3) waters within 200 nautical miles of the coasts of these land areas, including the islands.
Birds of South America - a fast way to search the bird taxonomy and distribution for South America
Species Lists of Birds for South American Countries and Territories pelo South American Classification Committee da American Ornithological Society (until 2016 American Ornithologists' Union)
Venezuela
Colômbia
Equador
Peru
Brasil
Listas das aves do Brasil e anterior Comitê Brasileiro de Registros Ornitológicos (CBRO)
Argentina
Chile
Antártida e região sub-antártica