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2017 AOS Classification Committee Proposals, Part 3

Here is the third and likely last batch of taxonomic proposals, submitted in the last year to the American Ornithological Society’s North and Middle American Classification Committee. Part 1 is here. Part 2 is here. Proposals accepted by the AOC Committee are incorporated into the ABA’s Checklist.

We suggest the usual caveat, that it’s important to note that these are just proposals and the committee has yet to vote on them formally. There are some that are unlikely to make the cut for whatever reason, but we include them here because they are interesting and worthy of discussion.

This post will only mention those changes that affect the ABA Area, but if you’re interested in the whole ball of wax – the AOS NAMACC’s jurisdiction includes all of the North America south to Panama – please refer to the official list of proposals at the AOS’s website (.pdf).


Revise the linear sequence of genera in Fringillidae, and transfer Serinus mozambicus to Crithagra

This fairly straight ahead proposal rearranges the genera in the finch family based on a handful of recent phylogenetic studies. Serinus mozambicus, commonly known as Yellow-fronted Canary, is an established exotic in the ABA Area in Hawaii and a good candidate for inclusion on the ABA list. It moves to genus Crithagra along with a few Old World relatives.


Split Brown Creeper (Certhia americana) into two species

The New World’s lone representative of the treecreeper family, the unique Brown Creeper consists of two “groups” with more than a dozen named subspecies. The Northern Group contains the birds that most birders in the ABA Area are familiar with, with the Southern Group only creeping (you’re welcome) into the ABA Area in southeastern Arizona but occurring through Mexico into northern Central America. Birders and ornithologists have long noted differences between these two groups where they overlap, with northern birds being generally larger and lighter than the southern birds. The proposal is based on a study that looked at genetic differences between the groups and found them to be fairly significant, with little or no gene flow occurring. In fact, the “boundary” between the two groups seems to correspond with well-defined forest types, and is consistent with boundaries seen in other nearctic/neotropic species pairs. The proposal suggests the name Nearctic Creeper for the northern group, with Brown Creeper retained for the southern, mostly non-ABA, group, which seems unnecessarily confusing. The committee suggests Nearctic and Neotropical Creeper for the two.

Brown Creepers in southeast Arizona, like this one from Cave Creek Canyon in Cochise County, are quite different from those elsewhere in the ABA Area. Photo: Jay McGowan/Macaulay Library (S30887780)


Split Nashville Warbler (Oreothlypis ruficapilla) into two species

Nashville Warbler isn’t often among the increasingly short list of likely splits in the ABA Area, but the species does consist of two subspecies that, while similar in appearance, don’t breed anywhere close to each other. The eastern subspecies ruficapilla breeds across the northeastern United States and much of southeastern Canada west through Manitoba. The western ridgwayi subspecies, often known as Calaveras Warbler, breeds roughly from southern British Columbia into California. The proposal cites differences in morphology, behavior, and vocalizations, and genetic studies done in the not too distant past found significant distance between the two suggesting that even if their breeding ranges did overlap, they wouldn’t interbreed. The proposal suggests the established name Calaveras Warbler for ridgwayi, and the somewhat uninspired Rusty-capped Warbler for ruficapilla, noting that Nashville Warbler is a pretty lousy name for this species. Can’t say I disagree with that last part, at least.


Lump Thayer’s Gull (Larus thayeri) with Iceland Gull (Larus glaucoides)

This proposal has been simmering for some time, as many birders have long since come to the conclusion that these two species actually represent one near-hemisphere spanning cline, from the entirely white-winged nominate Iceland Gull of western Europe to the muddy-winged Thayer’s of the Pacific Coast. The proposal suggest that the entire premise for considering Thayer’s as a full species is flawed, at best, from the very source and the 1960s research that more or less informed that decision is called into question. In that case, the path of least resistance would require that, in lieu of genetic research on these birds, that Iceland and Thayer’s Gulls be considered one species. Another option, that nominate Iceland Gull and Thayer’s Gulls are full species in their own right, and that the bird we call “Kumlien’s” Iceland Gull, which breeds in eastern Canada and winters in the east of North America, is a hybrid swarm, does not seem to be taken into consideration by the proposal. But short of genetic samples taken from birds on their isolated breeding grounds, that question may never be answered.

Dark Iceland Gulls on the west coast, like this one from Monterrey, California, have always been problematic to identify. The AOS might make that question much easier, though no less interesting. Photo: Paul Fenwick/Macaulay Library (S33021659)


Change the spelling of the English names of Le Conte’s Thrasher (Toxostoma lecontei) and Le Conte’s Sparrow (Ammodramus leconteii)

This proposal seeks to correct a typographical injustice done to the John LeConte by none other than John James Audubon himself. Audubon was given the type specimen of the bird that came to be called Le Conte’s Sparrow but he neglected to enter the appropriate information at the time as he was recovering from a near-death experience, having shockingly very nearly shot himself in the head with a borrowed shotgun. Instead of a hole in his head, he put a hole in poor Mr. LeConte’s name in the monograph, where it stuck for nearly 175 years. The thrasher’s name was derived from the sparrow, evidently, and thus both were wrong. The proposal suggests that the names officially delete the space. To be honest, this whole thing was news to me, as evidently I’ve been spelling the names incorrectly (but now correctly) for years. Go figure.


Add Common Scoter (Melanitta nigra) to the Main List

Add Blyth’s Reed Warbler (Acrocephalus dumetorum) to the Main List

Add Chatham Albatross (Thalassarche eremita) to the Main List

Add Red-legged Honeycreeper (Cyanerpes cyaneus) to the U.S. list

These are house-keeping proposals of the type we see every year. As the ABA incorporates AOS taxonomic decisions into our list, the AOS incorporates documentation of new bird records per the ABA into theirs. These four species are added to their respective lists based on documented sightings. The scoter, warbler, and honeycreeper in California, Alaska, and Texas, respectively. The Chatham Albatross, originally seen in 2001, was re-evaluated by the California Bird Records Committee in response to the split of Shy Albatross some years ago and unanimously accepted.


Split Bell’s Vireo (Vireo bellii) into two species

Bell’s Vireo in the ABA Area consists of four subspecies split into two groups, roughly eastern and western. The two groups differ primarily in plumage and behavior, with differences in vocalizations often cited as well. The western group, often referred to as “Least” Bell’s Vireo has long been considered distinct, and is a conservation concern in California, Arizona, and New Mexico. The proposal notes that any change in taxonomic treatment of this group will have conservation ramifications. With that in mind, it’s surprising that it was not until recently that a full genetic study was done on this species, and the results were as expected with the two populations segregating genetically as well as spatially. The proposal suggests that the name Bell’s Vireo be retained for the population in the center of the continent, while Least Vireo is used for the endangered southwestern birds.


The full list, including background information, recommendations, and the whole log story about Thayer’s Gulls is available here (.pdf). We’ll post the results of the voting when we see them this summer.

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Nate Swick

Nate Swick

Editor, Social Media Manager at American Birding Association
Nate Swick is the editor of the American Birding Association Blog, social media manager for the ABA, and the host of the American Birding Podcast. He lives in Greensboro, North Carolina, with his wife, Danielle, and two young children. He is the author of Birding for the Curious and The ABA Field Guide to Birds of the Carolinas.
Nate Swick

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  • Rick Wright

    They’re absolutely right about the spelling of LeConte, though John Lawrence LeConte seems to have harbored the occasional uncertainty himself.

    • Ted Floyd


      Is that the old spelling of what is today the most populous city in New Jersey?

      • Rick Wright

        I’m sure someone somewhere’s traced the passage of all those New York / Newyork / New-York names. So far as I know, though, “Newark” has always been written as such in the US.

  • ramanauskas

    “The committee suggests Nearctic and Neotropical Creeper for the two.” Oh, sure! Because the last thing we want are common names that are even vaguely descriptive! How about Greater/Lesser Brown Creeper or Light/Dark Brown Creeper? Or Northern/Southern Brown Creeper? Sheesh. Nearctic/Neotropical _Brown_ Creeper if they must.

    At least the Nashville Warbler split includes a somewhat descriptive name, though “rusty-capped” is not really the first thing I think of for that bird. At least it fits the Latin name.

    For the gull lump, I think I’ll just sit back and eat popcorn.

    • BF

      Every creeper is brown. The only thing immediately distinctive about Brown Creeper is that it lives in the Neactic and Neotropics, while the rest of the family is Old World.

      • Kirk Roth

        One other distinctive thing about the Brown Creeper – it is the only Certhia species which isn’t called a “Treecreeper.” If the names are to be changed anyway, it seems like a great time to align these.

  • Mike Patterson

    Regarding Thayer’s Gull: There is actually quite a bit of genetic work that has been done and it doesn’t do much to aid the argument in favor of Thayer’s Gull as a valid species. For starters I would point you to:
    J.-M. Pons, A. Hassanin, P.-A. Crochet, 2005, Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers. Molecular Phylogenetics and Evolution 37 (2005) 686–699

  • jmorlan

    Retaining the name “Bell’s Vireo” for part of what is currently known as Bell’s Vireo violates the rule laid out in the 7th edition of the checklist that when a split occurs, new names will be giving to the two daughter species (with rare exceptions). This rule is there for a reason, but seems to be ignored more often than not, presumably in the interest of nomenclatural stability. But there is nothing stable about Bell’s Vireo no longer meaning what it used to mean. Pity the poor eBird reviewer dealing with constant reports of Bell’s Vireo in Southern California or Arizona having to determine which species the observer saw. Did the reporter know about this split, or did they really mean a vagrant Eastern Bells? A unique name for the Eastern bird solves this problem and leaves the name “Bell’s Vireo” available for the combined species.

    • Ted Floyd

      Totally agree with this.

      And I pity not just the poor eBird reviewer, but also the poor biology major–or even professional ornithologist!–who is led to assume that the Least Vireo is an evolutionary propagule of (“split from”) the Bell’s Vireo. Somewhere out there, Ernst Mayr is rolling in his grave. Charles Darwin too. Willi Hennig, meanwhile, is just smirking.

      I am a huge admirer of the AOS (AOU) checklist committee, and am impressed by the rigor and thoughtfulness that goes into their deliberations and decisions. The birding community owes an incalculable debt to the professional ornithologists of the AOS. But they and I part company on the “logic” of splitting Species A into Species A and Species B. Do the math (do the logic): If A = A + B, then B = 0. Really?

      It’s already April 1 in St. John’s, so I’ll propose splitting the Bell’s Vireo into Shrub Vireo and Scrub Vireo.

      • Ryan Terrill

        I’m not really sure what the logic is behind this comment. A split means what we previously thought was one species is now considered two, not that the old species is dead, or that the name now applies to an ancestor. Hennig thought that “species” that were common ancestors “died” when they speciated and two new species were “born” – and that ancestor names shouldn’t be applied to “daughter” species for this reason. Is this what you’re referring to with the Hennig reference? If so, that’s not particularly applicable to this situation, nor is it really consistent with modern systematics. Bell’s Vireo can apply to different groups of populations in a pre and post-split sense, it just is a different definition of what Bell’s Vireos are called. A nomeclatural split is not the same as an evolutionary propagule (whatever that’s supposed to mean.) The evolutionary history of Bell’s Vireos hasn’t changed here – there are multiple distinct populations that share a common ancestor. What’s changed is the view of the amount of gene flow, and other demographic processes, between the populations. Bell’s Vireo, if defined as the eastern birds, just takes a narrower definition than it previously had. Least Vireo was considered the same species as Bell’s, and now is thought to be different. That doesn’t mean that the term Bell’s vireo applies to their common ancestor and must “die” along with the recognition of a speciation event. Take this example: if we decided to erect a new order for monotremes, we wouldn’t have to retire the term “mammals”, we’d just define it more narrowly.

        • Ted Floyd

          Indeed that would be a fine idea:

          As to the problem of splitting A into A and B, it’s laid out in the front matter in the AOU Check-list of 1998.

          Ryan, this isn’t about your own interpretation of gene flow, daughter taxa, usw. It’s about how the whole birding community receives the texts and traditions of the AOS. Google the exact phrase Cackling+Goose+split+from. Q.E.D.

          • Ryan Terrill

            I understand (but don’t really agree with) the semantic argument here; but I’m not sure why I get why Mayr and Darwin are rolling their graves, or why Hennig is laughing then, or why anybody would think that Least Vireo is a “propagule” (again, huh?) of Bell’s. Especially a biology student or ornithologist – what exactly is the point of confusion they would have?- what do you mean here? This split is absolutely based on demography and gene flow – not my interpretation of it, but the results from the Klicka study, which clarify the structure of the populations. Logically, a more appropriate structure would be A1=A2+B; or A(sensu pre-2017) = A (sensu post-2017) + B; which is fine and understandable.

          • Nico Franz

            I’d agree. The repeating of just “A” as a label for prior-/post-splitting conditions is not adequate as a syntactic solution (hence just names are too under-specified here), when the semantics change through the splitting act. Incidentally, we do have a logic representation and reasoning solution to account for such events. See

    • John Griffith

      I agree. And how about the western species being named the “Willow Vireo” rather than Least Vireo as it breeds more or less exclusively in willow-dominated riparian habitat, and most nests are hung in willow (Salix spp) and seep willow (aka mulefat) (Baccharis salicifolia). Pic is vireo nest in mulefat.

      Also, hello old lbvi friends Jim Greaves and Mark Holmgren : ) 2017 was our 32nd year doing lbvi and bhco stuff!

  • Kent Fiala

    The Nearctic does not end at the Mexican border. It looks to me like the major part of the range of the proposed split southern Brown Creeper still lies within the Nearctic, making Nearctic Creeper a poor name for the northern populations. Instead, I suggest that the names Mexican Creeper and ABA Creeper would be more nearly correct.

    • Adam Roesch

      Until the ABA adds northern Mexico 😉

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