Authorities
The taxonomy of Avionary (order, family, genus and species status and names) follows the taxonomy of Avilist 1^st version (The Global Avian Checklist, v2025) of June 2025. This consolidated list is the combined follow-up of IOC World Bird List (International Ornithological Congress) version 15.1 of March 2025, the eBird/Clements checklist and the checklist of Birdlife/ Handbook of the Birds of the World (HBW). Where still different the taxonlmy of the latter is also accounted for. Scientific names and English names used by other authorities, including eBird/Clements (2025), Howard and Moore (2018), British Birds/BOUC (2026), and the American Ornithologists’ Union AOU (2025), are also mentioned, under “Synonym Latin“ and “English Synonym”, respectively.

Species vs. subspecies
Bird names are species names in principle. Subspecies considered as full species by some authorities or authors but as subspecies by Avilist are also included as if they were species, for example Anas carolinensis. The variable status of such taxa is presented in the ‘Taxo’ line, where it is mentioned for example as ‘Avilist: subspecies of A. crecca’. The number of subspecies (following Avilist and HBW) is presented as well; if there are no separate subspecies, the species is indicated as Monotypic.

Genus
The scientific genus name used as an entry is the one used in Avilist v2025. Where an alternative name is sometimes used, for example in HBW, eBird/Clements, Howard and Moore, or was used in the past, this alternative is given below the preferred scientific (Latin) name. As an example, for Thalassarche cauta, the ‘Synonym Latin’ line gives ‘Diomedea cauta’. In special cases, two, three, or even four alternative genus names are presented. All such more or less well-known, including recent, alternative genus names can also be searched for. A special Holarctic species list S mentions most or all of the scientific synonyms, as well as a number of English synonyms.

Family
The family name is given as the scientific (Latin) name (ending in –idae). The family distribution of Avilist v2025 is followed. Alternative (previous) family names are given where appropriate. The multilingual Species Lists present the families according to Avilist.

Order
The higher taxonomic level: Order (ending in -iformes) is not mentioned in the search results for species. It is mentioned, however, in the search results for families (after “Taxo”).