Proposal (392) to South American Classification Committee

Elevate Dubusia taeniata stictocephala to species level

The Buff-breasted Mountain-Tanager (Dubusia taeniata) is a polytypic species found from the northern end of the Andes south to southern Peru, with an isolated population in the Colombian Santa Marta mountains (Paynter and Storer 1970, Isler and Isler 1987). The nominate subspecies (type locality “Santa-Fé-Bogota” Colombia) ranges from western Venezuela south to northern Peru, north and west of the Marañón low. The distinctive blue-crowned stictocephala (type locality in Junín, Peru) occurs from south and east of the Marañón low to southern Peru (Schulenberg et al. 2007). The Santa Marta birds, carrikeri, have some blue crowned streaking, unlike solid, blackish-crowned nominate, with the buff of the breast extending up to the center of the throat (depicted in Isler and Isler 1989). 

All three subspecies were originally described as species. Hellmayr (1936) treated stictocephalus as conspecific with taeniata, and Meyer de Schauensee (1966) treated carrikeri (described after Hellmayr 1936) as conspecific with taeniata. Those treatments have been followed by all subsequent authors (Paynter and Storer 1970, Isler and Isler 1987, Ridgely and Tudor 1989, Schulenberg et al. 2007). In October 2008, Hosner (Xeno-canto America, XC29739) and Robbins (MLNS 137644; note that the first 5-6 notes are under natural conditions, whereas the final 25 are after playback) independently recorded singing Dubusia in Junín, Peru, just south of the type locality for stictocephala. Upon returning from the field they compared their recordings with songs from a number of other localities throughout the species’ range and determined that the Junín birds sounded very different from birds north of the Marañón (multiple cuts on Xeno-canto and Macaulay Library of Natural Sounds, Cornell University web sites). Moreover, Lane had recorded birds (Xeno-canto America, cuts XC29538-9539) in October 2004 just south of the Marañón at Leimebamba, Amazonas, Peru, that match the vocal type from Junín. Birds just to the west and north of the Marañón give the typical nominate song (Ted Parker recordings from Cerro Chinguela, Cajamarca, and Huancabamba, Piura, Peru; MLNS, 21793, 21953). 

As can be readily heard and visualized spectrographically on both the Xeno-canto America and MLNS web-sites, the song of nominate consists of 2-3 loud, whistled notes, “feeeeu-bay” or “feeeeu-feeeu-bay” (Ridgely and Tudor 1989). The first two notes slur downward in frequency, with the third note (when given) having less of a frequency change. This song is consistent throughout the range of nominate (both east and west slopes), and according to Nick Athanas and Niels Krabbe (pers. comm.) the Santa Marta carrikeri also has a song similar to nominate. Birds continue to give this song-type even after playback (Paul Schwartz recordings from Venezuela; MLNS 70755-70756-70757). In striking contrast, stictocephala’s song is quite distinct from birds north of the Marañón, and is reminiscent of a Pipreola’s thin, high-pitched whistle. This song is a single-noted whistle that is sharply slurred downward in frequency. The single-noted song is continually repeated and is given at dawn as well as later in the morning and after playback (MLNS 137664).

Because of the dramatic break in song and plumage across the North Peruvian/Marañón low, we recommend that stictocephala be elevated to species status. Although the specific epithet signifies the crown is spotted, this region and the nape are actually heavily streaked with cerulean color. To reflect this distinctive plumage character, we recommend Cerulean-streaked Mountain-Tanager as the English name for D. stictocephala. As a final comment, we suspect that genetic data will further corroborate the Marañón break, and may even demonstrate considerable differentiation among nominate and carrikeri, despite the fact that these latter two taxa reportedly have similar voices.

Acknowledgments. Nick Athanas and Niels Krabbe kindly shared their knowledge about the vocalizations of carrikeri. Greg Budney and Jessie Barry at MLNS kindly made available on-line key cuts of Dubusia.

Literature Cited.

Isler, M. L. and P. R. Isler. 1987. The tanagers.  Natural history, distribution, and identification. Smithsonian Institution Press, Washington, D.C.

Meyer de Schauensee, R. 1966. The species of birds of South America and their distribution. Livingston Publishing Company, Narbeth, Pennsylvania.

Paynter, R. A., Jr. and R. Storer. 1970. Check-list of birds of the world.  Museum of Comparative Zoology, Cambridge, Massachusetts.

Ridgely, R. S. and G. Tudor. 1989. The birds of South America.  Vol. 1. The oscine passerines.  University of Texas Press, Austin.

Schulenberg, T. S., D. F. Stotz, D. F. Lane, J. P. O’Neill, and T. A. Parker, III.  Birds of Peru.  Princeton University Press, Princeton, New Jersey.

Mark B. Robbins, Pete A. Hosner, and Dan F. Lane, March 2009

____________________________________________________________________

Comments from Cadena: “NO, for a lack of published analyses.”

Comments from Nores: “NO. Yo estoy de acuerdo con Cadena de no aceptar cambios de este tipo que no estén apoyados por análisis publicados. Además no veo que haya un “dramatic break in plumage across the Peruvian Marañón low”. Las diferencias para mi son propias de subespecies.”

Comments from Remsen: “NO, but only on a technicality. I understand the frustration when vocal differences are known and now readily assessed by means of online recordings. However, I favor sticking to our policy of making changes based only on published analyses and comparisons of those recordings. Note that the above proposal needs only a little more work to be ready for submitting as a short publication. Just the process of putting together existing information as a SACC proposal represents the bulk of the work needed to get a short publication submission-ready. In other words, a proposal sufficiently detailed and rigorous to pass SACC is also very close to publishable as a journal note.”

Comments from Zimmer: “NO. My feelings about this proposal are similar to those of the preceding one (Troglodytes aedon/cobbi). I think Mark, Pete and Dan make an excellent case for splitting these birds, and that ultimately, this will be shown to be the correct course. But again, given that the SACC has generally maintained a policy of requiring some sort of published analysis before making a change, I reluctantly vote NO. If Mark and company could publish even a short paper with spectrographic examples of the vocal differences, I would happily change my vote.”

Comments from Jaramillo: “YES – Although I do think the authors should publish a short note, the vocal difference seems to clear to me and the data so readily accessible that I feel more at ease making this change than letting it sit. It seems to me that there are too few researchers, and even less time for them to do these types of things than we have open questions. However, I dislike the English name; it doesn’t quite roll of the tongue.”

Comments from Schulenberg: “YES. I'm with Al on this one. In the past, I've voted against any number of good-sounding proposals because of the lack of a "published analysis." But we've let a lot of decent ideas die along the way - many of which have yet to be written up for publication, years later - and in the meantime it's becoming easier and easier to assemble the relevant information online.

“I see some room, in other words, between "field guide taxonomy" (little or no documentation provided) and a Kevin Zimmer 30-page exhaustive survey. The point of a published analysis, after all, is in spreading and sharing data and the conclusions that stem from them. I think this proposal follows in the vein. If we agree that the authors convince *us* of the merits of their case, and if the data on which we base our conclusions are available to others, then we're only hurting ourselves by voting against it.

“The name "Cerulean-streaked Mountain-Tanager" is awkward, however. Can't you settle for "Blue-streaked Mountain-Tanager"? A four-word name (long!) with a four (!!) syllable opener is too much for me. Simplify, simplify.”

Comments from Stotz: “YES. This looks like a clear split. I agree with Jaramillo and Schulenberg that Cerulean-Streaked Mountain-Tanager is a bit too much. Tom’s suggestion of Blue-Streaked Mountain-Tanager sounds good to me.”

Comments from Stiles: “NO for now, for exactly the same reasons as in the previous proposal: a peer-reviewed publication should be required – especially for people like me who are unfamiliar with the taxa concerned.”

Comments from Pacheco: “YES. Voto sim pelas mesmas razões apresentadas na Proposal #391. Creio ser mais danoso – mascarando a real diversidade – manter táxons “agrupados” meramente por tradição/continuísmo do que tratá-los como distintos até que alguma análise corrobore o contrário.”