There are a number of different world bird lists available. The Clements Checklist of the Birds of the World is an established authority for world listing. The 6th edition was published in 2007 and, following the death of Jim Clements in 2005, is now being maintained by the Cornell Laboratory of Ornithology. Cornell are publishing regular updates to the list and BUBO Listing will endeavour to keep up with these updates. The latest updates incorporated are those from October 2022.
Not surprisingly, the taxonomic treatments of various species or subspecies differ between Clements and other authorities. If you are unclear about how any species you have seen relates to the species listed in Clements, then Contact Us and we will endeavour to help.
Note that English names follow Clements in general and thus are the preferred American names, 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).