The American Ornithological Society (AOS), formerly the American Ornithologists' Union (AOU), is "the oldest and largest organization in the New World devoted to the scientific study of birds". The AOS North American Classification Committee (NACC) maintains a checklist of North and Middle American Birds for which updates are regularly published.

The geographic area covered includes North and Central America from the boundary of Panama and Colombia northwards and including Hawaii, Bermuda and the West Indies. It is thus significantly larger than the area covered by the ABA list.

The most recent update incorporated in BUBO Listing is the 64th supplement published in Ornithology, https://doi.org/10.1093/ornithology/ukad023.

Note that English names follow AOS in general, hence Brant instead of Brent Goose, Common Merganser instead of Goosander, Loon instead of Diver (e.g. Common Loon and not Great Northern Diver), Jaeger instead of Skua (e.g. Parasitic Jaeger and not Arctic Skua) and 'gray' rather than 'grey'.

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