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Bulletin: New Splits

The American Ornithologists’ Union “Check-list Committee” has published an online preview of its decisions on dozens of taxonomic and nomenclatorial proposals that will take effect this year if there are no last-minute revisions.

The report includes splits of four species involving ABA-area birds, but none of them adds a species to the ABA Checklist. That’s because each divides a species already on the ABA Checklist from one outside the ABA area. Three other proposals would have added new ABA-area species, but those failed to gain approval.

Here are the splits that passed:

• Common Moorhen returns to its former name Common Gallinule (Gallinula galeata) in the New World as a separate species from Moorhen (G. chloropus) in the Old World. This vote passed unanimously, although one member believed the new name for “our” bird should be American Gallinule. A bird thought to be a vagrant from the Old World was photographed and collected on Shemya Island, Alaska, in October 2010. If accepted as a Moorhen, it would be the first ABA-area record.

Snowy Plover • Snowy Plover becomes Snowy Plover (Charadrius nivosus) in the New World and Kentish Plover (C. alexandrinus) in the Old World. The vote was 8–3, with the majority favoring the split because of genetic divergence and other differences between the two former subspecies. An interesting situation in Alaska arises in this case as well. Alaska’s only Snowy Plover record, photographed at the Nome River mouth in 1991, will now need to be reexamined to determine whether it can be identified as a Snowy or a Kentish.


• Bahama Warbler (Dendroica flavescens), a Bahamian endemic, is recognized as a distinct species from Yellow-throated Warbler, which will retain the name Dendroica dominica. The 8–3 vote was marked by disagreement over whether distinctions in mitochondrial DNA, plumage, and vocalizations were sufficient to warrant species status.

• Mexican Jay becomes two species, Mexican Jay (Aphelocoma wollweberi), which reaches its northern range limit in Arizona and southern New Mexico, and Transvolcanic Jay (A. ultramarina) in Mexico. The split was favored 9–2 based on differences in genetic structure, plumage, vocalizations, and measurements.

Here are the proposed splits that failed:

• Return of Mexican Duck (Anas diazi) to species status separate from Mallard. This vote was close: 5 in favor, 6 against. The dissenters felt that the degree of hybridization between the two has not been established and that phenotypic differences are inconclusive.

• Split of Mountain Chickadee into a Rocky Mountain–Great Basin species and a Pacific-region species resident in the Sierra Nevada and Cascades. The vote was 9–2 against separating them. Among various reasons, the majority felt that there was insufficient evidence of reproductive isolation between the two.

Audubon's Yellow-rumped Warbler • Split of Yellow-rumped Warbler into two, three, or four species. The present subspecies, “Myrtle” group (coronata), “Audubon’s” group (auduboni), “Black-fronted” (nigrifrons), and “Goldman’s” (goldmani) are all part of the picture. A split of Myrtle and Audubon’s, of course, would have added an ABA Checklist species. Black-fronted is a resident in Mexico, and Goldman’s occurs only in southernmost Mexico and Guatemala. Neither of those two has been recorded in the ABA area. The vote was 7–4 against any divisions of the Yellow-rumped complex until further genetic analysis and determination of the extent of interbreeding in the subspecies’ contact zones.

Taxonomically, the most far-reaching proposal accepted by the committee is an extensive rearrangement of wood-warbler genera in the family Parulidae. The new arrangement, adopted by an 8–2 vote with one abstention, will move many species into new genera and will end the venerable genus Dendroica. (Birds in that genus, whose Latin name nicely  means “tree-dwelling,” will now become part of the genus Setophaga, whose name means “moth-eating.” Ugh!—but that stems from standard rules of scientific nomenclature.

The parulid proposal was covered extensively in an article in the March 2011 issue of Birding and a WebExtra to that issue. The status of Yellow-breasted Chat is not clear to me. The proposal to the AOU intentionally did not include the chat in the Parulidae because recent studies have strengthened the view that it is not a wood-warbler. So, a question arises: Does the AOU vote automatically separate the chat from the Parulidae without fanfare, or was this subject not addressed explicitly because it wasn’t part of the particular generic rearrangements proposed?

All proposals and votes by the AOU panel—formally named the Committee on Classification and Nomenclature (North and Middle America)—are subject to change pending further data or discussion. The outcome of these proposals is not final until publication of the annual supplement to the Check-list of North American Birds in the July 2011 issue of AOU’s journal The Auk. Rarely, however, do any such last-minute changes occur.

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Paul Hess

Paul Hess

Paul Hess, the Birding "News and Notes" Department Editor, started watching birds at age 7 in Los Angeles. Now a retired newspaper editor in Pennsylvania, he formerly chaired the Pennsylvania Ornithological Records Committee, has contributed many articles to the journal Pennsylvania Birds, writes an ornithological news column for the Pennsylvania Society for Ornithology newsletter, edits the Three Rivers Birding Club newsletter in Pittsburgh, and has coauthored several National Geographic books on birds. Paul has received prominent awards for outstanding contributions to Pennsylvania ornithology and for bird conservation efforts in the state.
Paul Hess

Latest posts by Paul Hess (see all)

  • Transvolcanic Jay – what an epic name! It sounds like something you’d see in Middle Earth

  • Morgan Churchill

    Just as a correction, Connecticut Warbler is retained in Oporornis (now with only 1 species). The remaining members of Oporornis were merged into Geothylypis.

    I am not sure as well what is happening with the Yellow-breasted Chat. It isn’t a warbler, but none of the proposals have dealt with moving it. Presumably it remains within Parulidae, or it gets put into Incertae Sedis

  • First, a matter of housekeeping. Maybe it’s a just a problem on my end, but I can’t get through to the link mentioned at the top of Paul’s post. However, this works for me:

    Also, a comment on the split of Yellow-throated Warbler into Yellow-throated Warbler and Bahama Warbler. According to the AOU report, these birds will be Dendroica dominica and D. flavescens, respectively. But I assume they will actually be Setophaga dominica and S. flavescens, respectively.

    And, sorry to say, the AOU has once again ignored its own very good injunction against splitting species A into species A and B. The Yellow-throated Warbler should get a new name. The AOU lays forth their wise injunction against splitting A into A and B on p. xiii of the 7th edition (1998) of the AOU Check-list, a most-own book for every birder.

  • Morgan Churchill

    While I agree with you on when it comes to widespread species (Pacific and Winter Wren, Cackling and Canada Goose), I don’t think it is necessary to rename the widespread species when an island or otherwise restricted endemic is split off. Confusion is minimal in this case and the split won’t affect the majority of birders who are likely to come across mainland Yellow-throated.

    As another example, imagine if the southern Baja subspecies of American Robin is eventually split. Would you really prefer we come up with a new name for “our” robin? And what new name would we give American Robin? (or Yellow-throated Warbler?)

  • Hi, Morgan.

    Many people would agree with you on this. So does the AOU. According to the AOU Check-list, 7th edition, p. xiii: “However, we often have retained a well-known English name for a widespread North American form when a taxon that is either extralimital or restricted in distribution is separated from it. An example is the retention of the name Red-winged Blackbird for Agelaius phoeniceus when the Cuban population was separated as A. assimilis and named the Red-shouldered Blackbird.

    Although I do see validity in that point, my personal preference would be to apply that principle very, very–did I say very?–sparingly. Here’s why. Failure to do so promotes a highly erroneous notion about speciation; failure to do causes most of us–even well-trained biologists–to fall into the trap of thinking and saying, “The Red-shouldered Blackbird is necessarily an evolutionary offshoot or propagule of the Red-winged Blackbird.” That is not necessarily the case!

    Here’s an example to think about. As most of us know, MacGillivray’s Warblers are widespread breeders in upland and montane habitats in the western USA and Canada. But there’s also a well-isolated breeding population far to the southeast, in Mexico–not all that far from Brownsville, Texas, actually! And here’s the rub: It appears that that that east-central Mexican population is genetically pretty well-differentiated from the widespread USA/Canadian population. So, if the birds were to be split (I’m not saying that’s going to happen!), what would we name them?–maybe “Coahuila Warbler” for the Mexican popluation, while retaining “MacGillivray’s Warbler” for the more-widespread population? And that would cause people to say, very understandably so, “Coahuila Warbler” was split–i.e., it arose from, or evolved from–from “MacGillivray’s Warbler.” But it’s possible that precisely the opposite happened! Apparently, the very small east-central Mexican popluation contains greater genetic diversity than the entire USA/Canadian population; it may be the case that the widespread USA/Canadian population was a “founder population,” originating from the Mexican population.

    I think “standard English names, along with scientific names, should help us to think about the true relationships among bird populations. To invoke your example of the American Robin, there have been proposals floated out there, believe it or not, to change the bird’s name from “robin” to “thrush.” Granted, such proposals haven’t gained much traction. The name “robin” is just too well-established. Same thing, probably, with “Red-winged Blackbird” and “Canada Goose.” But, except for those very, very, very familiar birds, I would say it’s always a good idea to adopt two new names when a species is split. As much as I adored the old “Whistling Swan,” I think the AOU was right to toss out that beloved old name when the species was split.

    As to Yellow-throated Warbler, I’d say that bird doesn’t come anywhere near the “Red-winged Blackbird test,” if you will. I’d bet the farm on the following: Fewer than 1% of Americans have ever heard of the “Yellow-throated Warbler.” It’s a birder’s bird. I’d change its name in a heartbeat. We birders would get used to the new name soon enough, just as we got used to “Tundra Swan.”

  • Morgan Churchill

    In my opinion, common names really shouldn’t strive to make evolutionary sense, since when you think about it, most don’t.

    From my personal experience, most birders don’t put a whole lot of evolutionary thought into the relationship between x and y when x is split from y. On the other hand, I run into many many more birders that assume that birds with similar “generic” names are related to one another. American Robin is a great example. It’s not closely related to the European robin, and neither species is closely related to the Australian robins. But there are lots of other examples. Our “sparrows” are not really sparrows in the old world sense, but rather buntings (and genetic evidence suggests that they are at the family level distinct from them as well). Our tanagers are not tanagers, but rather cardinal-grosbeaks, and to add an extra layer of confusion most of the SA cardinals are tanagers!

    Common names should strive for stability and consistency. They should only be changed when maintaining one name would lead to confusion about all names Under that philosophy, Yellow-throated should remain Yellow-throated, but I will grant you retaining Winter Wren and Canada Goose were probably not the best options (or Common Gallinule!)

  • My question is answered: The Yellow-breasted Chat will remain classified by the AOU this year as a wood-warbler in the family Parulidae. An AOU “check-list committee” member gave me that information today.

    The annual check-list supplement to be published in July will merely point to recent mitochondrial DNA analyses indicating that the chat’s genus Icteria represents an old lineage of uncertain affinities, probably related to the Parulidae, Icteridae, or Emberizidae.

    In retrospect, I suppose the status quo shouldn’t be surprising. After all, the committee did not receive a formal proposal in the past year that explicitly recommended moving the chat out of the Parulidae.

    Coincidentally, last night members of the Three Rivers Birding Club in Pittsburgh saw a wonderfully researched and beautifully illustrated program on the history of wood-warbler taxonomy and nomenclature. Chuck Tague, a highly regarded western Pennsylvania naturalist, updated it to include information from Birding magazine’s coverage of the new AOU rearrangement of parulid genera.

  • Excellent points, Morgan and Ted.

    I’ve long thought that, given its nearly religious devotion to palm trees most of its year, the Yellow-throated Warbler should be called, “Palm Warbler.”

    I have no basis for judgement regarding the Bahamas population but I hear it likes pines, so maybe it could be called, “Pine Warbler.”

    Oh wait, that doesn’t solve anything.

  • Regarding Yellow-breasted Chat’s taxonomic relationship. Why not Shrike? I’ve seen them carry tree-frogs into nest sites – vertebrates! How does that square with it being “insectivorous”? Just asking, and adding comment for additional information regarding what to “name” it. Yellow-breasted Chat, as a name, says nothing “warbler” to me! Nor does its vireo/shrike like bill.

  • Perhaps, as another example, it is “yellow-breasted jay”, as its bill resembles that of the North American scrub-jays…

  • A bird thought to be a vagrant from the Old World was photographed and COLLECTED on Shemya Island, Alaska, in October 2010. If accepted as a Moorhen, it would be the first ABA-area record.

    What is it with you lot and guns? You shot a Moorhen!!!!!

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