No more ABA-area tanagers? Not so fast!

2009 July 21
by David J. Ringer

NAIROBI, KENYA — By now, most of us have heard that the Piranga tanagers (e.g., Scarlet Tanager, Summer Tanager, and Western Tanager) are not “true” tanagers in the family Thraupidae but instead belong to the Cardinalidae, a family that includes familiar North American species like Northern Cardinal, Rose-breasted Grosbeak, and Lazuli Bunting. The American Ornithologists’ Union effected this change on the South American list in 2008 and on the North American list this year after several years of accumulating genetic evidence.

In the ensuing discussions on email lists and blogs, I’ve seen some comments that either imply or state specifically that no members of the Thraupidae occur regularly in the ABA area.

For example, last year on the ABA PEEPS blog, Bill Maynard reacted to the news that the SACC had transferred Piranga and that Spindalis doesn’t belong in Thraupidae either (more on that in a minute): “If this thought is upheld by the NACC, we will no longer have any ABA Area representatives left in the Tanager Family…” (Taxonomic Changes ?).

Mike Bergin’s recent statement that the Piranga change leaves “the ABA region mostly bereft of true tanagers” is closer to the truth — though probably not for the reason that you’re thinking.

Savvy listers will point out that the Western Spindalis (Spindalis zena) occurs as an ABA code 3 vagrant to southern Florida. And Spindalis is currently included in the Thraupidae by the AOU and most other authorities.

But that’s not where it belongs. In the ABA PEEPS post referenced above, Maynard reports: “[Dr. Van Remsen], a current member of both NACC and SACC, said that Spindalis is certainly not a tanager.” In fact, it may belong somewhere rather unexpected, like the New World warbler family, Parulidae (scroll down to the “Teretistrinae” section).

If Thraupidae were only losing members, the ABA area might be left without any representatives. But, there is one species that breeds regularly in the ABA area and will, when the taxonomic dust settles, belong in the Thraupidae.

Any guesses?

Here she is, in a fine shot by Corey Finger (used with permission), North America’s only resident tanager:

North America's only resident tanager?

Got it yet? It’s the White-collared Seedeater, Sporophila torqueola, a tiny, finch-like bird that reaches the northernmost extent of its range in the Lower Rio Grande Valley, where it resides in dense reeds along the Rio Grande River and nearby reservoirs in Texas. Sporophila is currently placed in Emberizidae (New World sparrows, towhees, some buntings) by the AOU and all other authorities I know of except the IOC. Genetic evidence, however, shows that Sporophila is embedded in the Thraupidae!

The White-collared Seedeater may be North America’s only breeding tanager species, but three others occur as ABA code 4 vagrants:

  • Bananaquit, Coereba flaveola. A vagrant to southern Florida. Once placed in its own family and now treated as incertae sedis (position uncertain) by the AOU, the Bananaquit is a tanager. In fact, it appears to form a clade in Thraupidae with the Gal├ípagos finches and the Tiaris grassquits! (For discussion and citations, see the SACC page and scroll down to foonote 18 under the Incertae Sedis heading.)
  • Yellow-faced Grassquit, Tiaris olivaceus. This species occurs as a rare vagrant to southern Florida and Texas. This and the next species are currently placed in Emberizidae by the AOU NACC. Oh, and the genus Tiaris is paraphyletic.
  • Black-faced Grassquit, Tiaris bicolor. Also a vagrant in southern Florida.

If you’re like me, you’re probably thinking, Interesting … but where’s the proof? And why aren’t these changes reflected on major checklists? Well fortunately for you, I’ve dug up some references.

In a 2004 paper titled Molecular phylogenetics and diversification of the genus Sporophila (Aves: Passeriformes) Lijtmaer et al. stated: “[I]t is now widely accepted that many finch-like genera (so-called ‘tanager-finches;’ Sibley and Ahlquist, 1990) are members of the Thraupini (tanagers) and not the Emberizini (New World sparrows), as it was traditionally believed” and cite a spate of papers going back to 1988 to back up the claim.

In 2007, Klicka et al. published Defining a monophyletic Cardinalini: A molecular perspective, a genetic study that sampled 175 species (in their words, “the taxonomically most complete study of New world nine-primaried oscines done to date”). The paper supports all of these conclusions and a lot more.

Checklist committees are biding their time, waiting for more data before making big changes. For example, the SACC says in one footnote, “However, taxon sampling has been so incomplete that a wholesale redefining of the limits of the family [Emberizidae] must await publication of additional data” (footnote #1 under Emberizidae). The New World nine-primaried oscines (usually used to mean the Fringillidae, Emberizidae, Cardinalidae, Parulidae, Icteridae and Thraupidae as currently defined) are an extremely diverse and complicated bunch, and family limits are going to change radically in the next few years.

Thraupidae will probably end up with around 400 species, including the four discussed above. Unless everything is jammed into one huge family (like Sibley and Monroe’s Fringillidae) of 800+ species. Or unless ‘Thraupidae’ is split into more than one family. (Frankly, I’m becoming less and less enamored of a rank-based taxonomy….)

For more on the redefined Thraupidae, see John Boyd’s detailed Thraupidae taxonomy and Don Roberson’s colorful Thraupidae family page.

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5 Responses
  1. July 21, 2009

    Seedeaters and grassquits are tanagers, not finches? Crazy!

    Your continued analysis of taxonomical changes is excellent, David. What do you mean when you say you’re “becoming less and less enamored of a rank-based taxonomy…”?

    • David J. Ringer permalink*
      July 22, 2009

      Thanks, Mike! In rank-based taxonomy, certain groups of organisms are assigned to certain levels in a hierarchy– e.g., Cardinalidae is a “family,” Cardinalis is a “genus,” etc. However, these assignments are totally arbitrary. It’s possible, as Sibley and Monroe did, to lump virtually the entire nine-primaried oscine assemblage (over 800 species) into a single family. Or, it can be divided into several, as we tend to do today. Or, it could be subdivided much more finely (e.g., splitting Thraupidae into three or more families). When does a group qualify as a “family” versus a subfamily or a tribe or a supergenus? And why do taxonomists spend so much time worrying about this question? It tends to make us think that certain groups are somehow more important or more distinctive or more significant than other groups (“Oh, that only a subfamily!”) when in fact this isn’t the case. My thoughts on all this are still rather fuzzy I’m afraid. Christopher Taylor’s article Phylogenetic Nomenclature – Oui ou Non? is an great introduction to this topic.

  2. July 21, 2009

    Great, weird, fascinating stuff, David.

    I also kind of love the fact that Darwin’s Galapagos Finches are, in fact, Darwin’s Tanagers.

    They’re everywhere. Well, except for most of North America, apparently.

    • David J. Ringer permalink*
      July 22, 2009

      Indeed. This whole assemblage of birds shows tremendous flexibility in selecting and accessing food, so their behaviors and bill structures (which, unfortunately, were among the major characters used to classify them in the first place) vary wildly. This is well studied in the Galápagos finches, of course. So we have the Hawaiian honeycreepers embedded in the finches, the seedeaters embedded in the tanagers, and so on! Wondrous.

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