Agreeing on a taxonomy is not easy. Not only does bird taxonomy vary significantly from one authority to another, but it is in a state of constant change. New species are still being discovered, and subspecies are split and lumped based on ornithological studies.
Wikipedia's taxonomy for bird species, subspecies, genus, family and order pages follows that of the IOC, unless consensus determines there's a reason not to. The IOC World Bird List is now updated twice a year. The IOC is also the de facto standard for English bird names. This decision does not affect country, state or other regional lists that use a different, named, taxonomy, or other articles that discuss bird biodiversity or birds in general. Exceptions may be made in particular cases for either taxonomy or names. Where disagreement exists between the major taxonomic authorities, articles should note this.
The Handbook of the Birds of the World was published in 16 volumes between 1992 and 2013. The text is available online with a subscription from HBW alive. The descriptions of the individual species have been updated to reflect changes in taxonomy, but (as of 2016) the introductory articles providing an overview of each family contain the original printed text. The printed edition included 9,972 species.
In 2014-16 Josep del Hoyo and associates authored an illustrated checklist in two volumes:
del Hoyo, Josep; et al. (2014). HBW and BirdLife International Illustrated Checklist of the Birds of the World, Volume 1: Non-passerines. Barcelona: Lynx Edicions. ISBN978-84-96553-94-1.
del Hoyo, Josep; et al. (2016). HBW and Birdlife International Illustrated Checklist of the Birds of the World, Volume 2: Passerines. Barcelona: Lynx Edicions. ISBN978-84-96553-98-9.
The illustrated checklist was published jointly with BirdLife International. BirdLife International is the Red List authority for birds, for the International Union for Conservation of Nature. The two volumes list 4,372 non-passerines and 6,592 passerines giving a total of 10,964 species. Compared with the printed edition of HWB, Volume 1 has 30 lumps and 462 splits while Volume 2 has around 41 lumps and 628 splits. The authors used a points based method to assess whether a taxon should be considered as a subspecies or species. This resulted in many taxa that have traditionally been classed as subspecies to be elevated to species level. At the same time a smaller number of species were demoted to the subspecies rank. The use of this procedure has been criticised by James Van Remsen, Jr.:
Remsen, J.V. Jr (2015). "Review of HBW and BirdLife International Illustrated Checklist of the Birds of the World Volume 1: Non-passerines". Journal of Field Ornithology. 86 (2): 182–187. doi:10.1111/jofo.12101.
Remsen, J.V. Jr. (2016). "A "rapid assessment program" for assigning species rank?". Journal of Field Ornithology. 87 (1): 110–115. doi:10.1111/jofo.12142.
Although a subscription is required to access the species and family articles, some other pages are open access:
The taxonomy used by HBW alive is available as a large web page:
A key by James Jobling to the scientific names used in ornithology. This is an expanded and updated version of the text in Jobling's 2010 book The Helm Dictionary of Scientific Bird Names:
Jobling, J.A. (2017). del Hoyo, J.; Elliott, A.; Sargatal, J.; Christie, D.A.; de Juana, E. (eds.). "Key to Scientific Names in Ornithology". Handbook of the Birds of the World Alive. Lynx Edicions. Retrieved 7 January 2018.
A list of abbreviating used in ornithological publications:
Updates and corrections are posted online once a year in August by the Cornell Lab of Ornithology. The eBird database uses the Clements Checklist - see here. The August 2016 edition of the Clements/ebird list included 10,514 species in 237 families.
North and Middle America - American Ornithological Society
The American Ornithological Society (formerly the American Ornithologists' Union) maintain a Checklist of North and Middle American Birds. A print edition was published in 1998:
American Ornithologists' Union (1998). Checklist of North America Birds (7th ed.). Washington DC: American Ornithologists' Union. ISBN1-891276-00-X.
Updates to this list are published annually in July as open-access articles in the Auk. The book and the updates (Supplements) are available for download. The updates explain the rationale for the changes. A recent example is:
Chesser, R.T.; et al. (2016). "Fifty-seventh Supplement to the American Ornithologists' Union Check-list of North American Birds". The Auk. 133 (3): 544–560. doi:10.1642/AUK-16-77.1.
The current AOS checklist is also available online and in CSV format. Proposed changes currently being considered by the Committee on Classification and Nomenclature of North and Middle American Birds (NACC) are posted online. Earlier proposals are also available.
Harrop, A.H.; et al. (2013). "The British List: A Checklist of Birds of Britain (8th edition)". Ibis. 155: 635–676. doi:10.1111/ibi.12069.
Beginning in 2002 the BOU have published the recommendations of their Taxonomic Sub-Committee of the BOU Records Committee as open-access articles in the Ibis. A complete list of articles is available from the BOU website. A recent article is:
The updated BOU list of British Birds is available online. In January 2017 the BOU announced that from 2018 they would follow the IOC World Bird List for the taxonomy of birds on the British List.
Authorities for taxonomy
Check-list of Birds of the World published from 1931 to 1987 in 16 volumes gives the authorities for genera, species and subspecies. The early volumes were edited by James Lee Peters. Scans of all volumes are available from the Biodiversity Heritage Library
History and Nomenclature of Avian Family-Group Names is a monograph by Walter Bock published in 1994 that provides the authorities for bird families. It can be downloaded from the website of the American Museum of Natural History as a 48MB pdf file:
Priority! The Dating of Scientific Names in Ornithology by Dickinson et al. published in 2011 provides information on publication dates. The complete text can be downloaded from Reseachgate as a single pdf.
Avibase is a website hosted by Bird Studies Canada. For each taxon the database tracks the common name and binomial name used by different authorities over time. It also lists the common name in languages other than English.
There are also a number of family monographs (such as the Hayman "Shorebirds" and Harrison's "Seabirds" in the Helm Identification Guides series); some are available on line at Amazon using the Search Inside feature. Although a mine of information, these books reflect the authors' idiosyncrasies and soon become dated.
A number of useful free to view online resources exist that are useful in writing bird-related articles:
Referencing (free scientific articles from ornithological journals etc.)
SORA Searchable online research archive, University of New Mexico. This site has decades worth of archives of the American ornithology journals, such as The Auk, The Condor, Journal of Field Ornithology, Ornitologia Neotropical, Studies in Avian Biology Pacific Coast Avifauna, and the Wilson Bulletin. Coverage ends around 2000, but still extremely useful. The ability to search almost all journals and browse issues exists on the front page.
PALMM Textual Collections a State University of Florida project. Several monographs available via All Collections search, such as Pierce Brodkorb's "Catalogue of Fossil Birds".
Forktail - the journal of the Oriental Bird Club. Deals with South, East and Southeast Asia and surroundings. All except the most recent issues available.
Birds of North America, Cornell University's project collecting information on all bird species breeding in the American Birding Association area. It isn't free, but available for 40 USD a year. Access is sometimes available via university libraries.
Malimbus, The Journal of the West African Ornithological Society; as well as the even older Bulletin of the Nigerian Ornithologists' Society. Mostly covers bird distribution in sites across the area, but also notes on behaviour and ecology of obscure birds from a little studied part of the world. The Journal is bilingual and some articles are in French.