The updates include changes of recommended names or classification, additions of newly described species, corrections of nomenclature, and updates of species taxonomy. The IOC World Bird List complements three other primary world bird lists that differ slightly in their primary goals and taxonomic philosophy, i.e.

Avibase is an extensive database information system about all birds of the world, containing over &1 million records about 10,000 species and 22,000 subspecies of birds, including distribution information for 20,000 regions, taxonomy, synonyms in several languages and more.

The fox sparrow is a large New World sparrow. It is the only member of the genus Passerella , although some authors split the species into four. Source: Wikipedia

Sooty fox sparrow, Sacramento, California. More specific information regarding plumage is available in the accounts for the various taxa.. Red fox sparrow, P. i. iliaca (Merrem, 1786) – this taxon breeds in the taiga of Canada and Alaska and winters in central and eastern North America. This is the brightest colored group.

Multiple sources suggest that the Fox Sparrow (Passerella iliaca) may com-prise three or four species (Zink 1986, 1994, 2008, Byers et al. 1995, Rising 1996, Dunn and Alderfer 2017).