There might be a bit of a misunderstanding here: the default English names of AviList v2025 are in the vast majority of cases just the preexisting IOC common names[1] (with a small number of exceptions including species not yet split/lumped in IOC v15.1, in which cases the AviList names are what the IOC names would’ve been). An English names committee will be established for future versions of AviList, but the first version didn’t involve “finding [compromises among the three] lists” in terms of default common names. (This is explained in multiple places on the AviList website: 1 2 3)
(The IOC English names themselves reflect to some extent a compromise for species with multiple established English names: some species get the American or otherwise non-British name [e.g., loons instead of divers, including common vs. great northern and yellow-billed vs. white-billed as the descriptors for G. immer and G. adamsii, respectively; jaegers instead of skuas, including parasitic vs. Arctic as the descriptor for S. parasiticus; red vs. grey phalarope; horned vs. Slavonian grebe; Lapland longspur vs. bunting; common and thick-billed murre vs. common and Brünnich’s guillemot], others get the British or otherwise non-American name [e.g., grey vs. black-bellied plover, black-necked vs. eared grebe, sand martin vs. bank swallow, little auk vs. dovekie, rough-legged buzzard vs. hawk, Siberian tit vs. gray-headed chickadee], and a few get a little of both [such as black-throated loon, instead of black-throated diver or Arctic loon, and brant goose, instead of brent goose or brant]. As for spelling differences, the list standardizes some words [like grey] to the British spelling, and others [like color] to the US spelling [but its guidelines on this also encourage users of the list to use whatever spelling is appropriate for a given situation]. edit: AviList will likely continue in future versions to list multiple alternate English names where they exist—see above links and previous comments posted while i was typing this)
It’s because the IOC checklist (which the AviList English name column corresponds to—see above) follows an entirely different set of rules for hyphenating English names than Clements/AOS (and HBW/BLI for that matter).
IOC restricts hyphens to “bird-bird” group names, like hawk-eagle, as well as some “a-b” names where the bird in question isn’t a part of the group(s) referred to by b alone, such as painted-snipe and stone-curlew (as well as other compound names which would otherwise would be a single word but in these particular cases that’d be difficult to parse due to length or awkward letter combinations, like white-eye, bee-eater, thick-knee, or foliage-gleaner, but that’s the case for all lists). All two-word collective names involving any non-bird word and a bird group (that the bird in question belongs to), such as sand plover, are unhyphenated.
I’m unsure whether the hyphenation practices of the Clements checklist are formally codified, but for the most part Clements has tended to align with e.g. NACC and SACC in generally following Parkes (1978), with hyphens typically used to denote relationships: some (but not all) two-word collective names that correspond to a clade are hyphenated (e.g., whistling-duck), while two-word names that have been hyphenated in the past but which don’t correspond to monophyletic groups have the hyphen removed[2] (e.g., night heron, black hawk, ground dove).
The HBW/BLI checklist has its own set of hyphenation practices. Again, i’m not sure these are formally written down somewhere, but it seems that many if not most two-word names that have long been hyphenated, and/or that would be more clearly understood with a hyphen, retain a hyphen (so, for example, reed-warblers, leaf-warblers, bush-warblers remain as-is, whereas Clements removed those hyphens a little while back because not all birds with each of those terms in its common name form respective monophyletic groups, and IOC didn’t hyphenate them from the start); however, there are also cases where hyphens have been removed following widespread adoption of the unhyphenated form (e.g., ground dove, black hawk), and i’m not sure if there’s any pattern to when this happens. (HBW/BLI has its own capitalization guidelines as well: the second part of a hyphenated name is always lowercase, unlike in other lists where it’s capitalized if it’s a bird group to which the species in question belongs. Furthermore, unlike IOC and Clements, which standardize variable spellings to one particular option across the board, in at least one case—color vs. colour—HBW/BLI standardizes the spelling by region, using the former for birds in the Americas and the latter for birds elsewhere. On the topic of sand-plover vs. sand plover, they use a third option: sandplover.)
(A fourth set of rules that’s been proposed is to hyphenate “noun-bird” but not “adjective-bird” names, resulting in, say, night-heron, sea-eagle, and sand-plover on the one hand, and whistling duck, diving petrel, and collared dove on the other.)
with their corresponding formatting standards ↩︎
(when someone catches it and proposes doing so, that is. there are still a number of hyphenated names in Clements [and some in the NACC and SACC lists for that matter] that have been known for some time to not correspond to clades but have yet to be addressed) ↩︎