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2017 AOS Classification Committee Proposals, Part 2
Here is the second 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. 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.
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).
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Treat the subspecies (A) spectabilis and (B) viridiceps as separate species from Eugenes fulgens (Magnificent Hummingbird)
Magnificent Hummingbird is a large, dramatic hummingbird that breeds in the ABA Area in southeast Arizona with records of vagrants scattered elsewhere throughout the continent. The species consists of three subspecies, the northern of which, fulgens, was formerly considered separate from the southern two, spectrabilis and viridiceps, until 1945, when the two populations were lumped based on little practical evidence – the northernmost and southernmost subspecies, respectively, fulgens and spectabilis, are pretty distinct, but the sort of intermediate viridiceps complicates things. They have been considered conspecific ever since, given the name of the northern group, Rivoli’s Hummingbird, until 1983. The proposal would split off spectrabilis and viridiceps into new species. The former seems a good bet, though the latter is less clear. It seems most likely viridiceps would remain in the fulgens group, if I read the proposal correctly. The split would resurrect Rivoli’s Hummingbird for the northern, and ABA relevant, group, and either bring back the old name for spectrabilis, the decidedly lackluster Admirable Hummingbird, or come up with something new.
A Magnificent Hummingbird split may see the birds in the ABA Area revert to their old name, Rivoli’s Hummingbird (Photo: Jason Vassallo/Macaulay Library S30580087)
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Revise the classification of the Icteridae: (A) Add seven subfamilies; (B) Split Leistes from Sturnella; (C) Resurrect Ptiloxena for Dives atroviolaceus; (D) Modify the linear sequence of genera
This proposal concerns a wholesale rearrangement of the blackbirds and orioles, primarily affecting species that occur to the south of the ABA Area where the core of Icterid diversity exists. Aside from a new order, the most interesting thing about the work informing this proposal is that it found that genus Xanthocephalus, or Yellow-headed Blackbird, is part of a very old lineage that lies alongside, and separate from, the other Icterids.
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Revise familial limits and the linear sequence of families within the nine-primaried oscines
This is another big move from a major study that affects nearly all of the perching birds in the ABA Area, but at the family level rather than the species level. There are three big take-aways here. The first is that this proposal finally places many of the neotropical incertae sedis (uncertain placement) birds more certainly. The second is that the Old World Buntings and the New World Sparrows, which are morphologically and behaviorally similar and have been considered together for a while in the family Emberizidae, are not that closely related and will be separated, with our sparrows forming the family Passerellidae. And third, the Yellow-breasted Chat is no longer part of the wood-warbler family, Parulidae, and gets its own family Icteriidae, not be confused with the blackbird family Icteridae.
The weird and wonderful Yellow-breasted Chat, a warbler no longer. (Photo: Doug Hitchcock/Macaulay Library S8995042)
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Lump Acanthis flammea and Acanthis hornemanni into a single species
2017 marks the return of the redpoll lump, which was not accepted by the committee last year. This is more or less a re-submission of that 2016 proposal, with some additional work included at the request of the committee. I’ll say now what I said last year, that the differences between Hoary and Common Redpoll are more continuous rather than discrete, occupying a continuum line from big pale Hoary all the way to small streaky Common with most birds falling between. This is in line with what field birders who have regular experience with the two have been saying for years. More, reports of Hoary and Common Redpolls sorting themselves by type where their breeding ranges overlap appears to be not well backed up. The proposal asserts that the burden of proof now appears to be on those proposing that redpolls are multiple species. Abandon hope, all ye who don’t want to lose the tick on your list.
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Split Lanius excubitor into two or more species
Lanius excubitor has long been considered a holarctic species called Northern Shrike in the New World and Great Gray Shrike in the Old World. Genetic work on Lanius suggests that the group we call Northern Shrike is more closely related to the North American Loggerhead Shrike than Great Gray Shrike in Europe and should be considered to be two separate species. But this is no normal Old World/New World split. The east Asian subspecies sibiricus was found to be closer to the North American borealis than the European/West Asia excubitor and should be considered with the former. So while there are records of extralimital shrike in western Alaska which may well represent sibiricus, those birds would also be Northern Shrike.
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Revise the generic classification and linear sequence of Anas
The dabbling ducks have been stuck together in the genus Anas for more than 250 years. This proposal moves some around, and gives other new genera. Baikal Teal, a rare ABA Area vagrant, moves into genus Sibrionetta. Vagrant Garganey and residents Blue-winged Teal, Cinnamon Teal, and Northern Shoveler go to genus Spatula. Gadwall, both wigeon, and Falcated Duck will be in genus Mareca. The rest of the Mallard complex, plus Northern and White-cheeked Pintail and Green-winged Teal, remain in Anas, but with some rearrangement.
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The full list, including background information and recommendations, is available here (.pdf). We’ll have a look at subsequent proposals as they’re released.
Join the American Birding Association at www.aba.org!
Source: http://blog.aba.org/2017/02/2017-aos-classification-committee-proposals-part-2.html
