Proposal (79) to South American Classification Committee

 

Treat Poospiza whitii as separate species from P. nigrorufa

 

Effect on South American CL: This proposal would split our Poospiza nigrorufa into two species, with recognition of Andean whitii group (with wagneri) as a separate species.

 

Background: The bird we treat as one species, Poospiza nigrorufa (Black-and-rufous Warbling-Finch), has a disjunct distribution, with the subspecies whitii and wagneri in the Andes from central Bolivia to northern Argentina and mountains of Córdoba, and the other in the lowlands from s. Paraguay and se. Brazil south through ne. Argentina to e. Río Negro. This follows the traditional classification (e.g., Hellmayr 1938, Meyer de Schauensee 1966, 1970, Paynter 1970).

 

New information: Ridgely & Tudor (1989) considered the whitii group to be a separate species from P. nigrorufa, with the following justification:

 

"We believe se. lowland nigrorufa and Andean whitii (with Bolivian wagneri) represent full species, though they have recently most often been considered conspecific. Color and tail patterns differ (at least as much so as in some other Poospiza currently given full species status); furthermore, their primary songs also differ (R. Straneck and pers. obs.)"

 

Narosky & Yzurieta (1989) treated them as conspecific but stated: "Mountain race: very different melodious song."

 

Sibley & Monroe (1990) followed this treatment and considered them allospecies that form a superspecies. Mazar Barnett & Pearman (2001) treated them as separate species.

 

[Lougheed et al. (2000) included samples of whitii in their analysis but not nigrorufa.]

 

Analysis: The plumage differences are indeed substantial, as Bob noted, but they are mainly in degree of "saturation" rather than pattern per se. Andean birds are dramatically darker chestnut than nominate birds, and are darker dorsally as well; the tail patterns differ in extent of white. However, juvenal whitii look very much like nominate nigrorufa adults in being a much paler, more rufescent brown (and I suspect this is why the traditional treatment has been as conspecific.

 

The vocal differences may be dramatic, but without formal published documentation, sonograms, etc., I cannot evaluate the evidence, which, as far as I can tell from what is published, is essentially hearsay.

 

On the other hand, the plumage differences between whitii and nigrorufa are less than some allospecies pairs in the genus, such as melanoleuca and cinerea.

 

Recommendation: I reluctantly vote "NO" on this proposal. I would be surprised if a formal analysis does not support the Ridgely-Tudor split, but that's what we should require, in my opinion, to change from traditional species limits. A published, quantitative analysis of differences in song is what I need to be convinced on this one.

 

Literature Cited:

 

HELLMAYR, C. E. 1938. Catalogue of birds of the Americas. Field Mus. Nat. Hist. Publ., Zool. Ser., vol. 13., pt. 11.

LOUGHEED, S. C., J. R. FREELAND, P. HANDFORD, AND I. T. BOAG. 2000. A molecular phylogeny of warbling-finches (Poospiza): paraphyly in a Neotropical emberizid genus. Molecular Phylogenetics and Evolution 17: 367-378.

MAZAR BARNETT, J., AND M. PEARMAN. 2001. Annotated checklist of the birds of Argentina. Lynx Edicions, Barcelona.

MEYER DE SCHAUENSEE, R. 1966. The species of birds of South America and their distribution. Livingston Publishing Co., Narberth, Pennsylvania.

MEYER DE SCHAUENSEE, R. 1970. A guide to the birds of South America. Livingston Publishing Co., Wynnewood, Pennsylvania.

NAROSKY, T., AND D. YZURIETA. 1989. Birds of Argentina & Uruguay. Asociación Ornitológica del Plata.

PAYNTER, R. A., JR. 1970. Subfamily Emberizinae. Pp. 3-214 in "Check-list of birds of the World, Vol. 8" (Paynter R. A., Jr., ed.). Museum of Comparative Zoology, Cambridge, Massachusetts.

RIDGELY, R. S., AND G. TUDOR. 1989. The birds of South America, vol. 1. Univ. Texas Press, Austin.

SIBLEY, C. G., AND B. L. MONROE, JR. 1990. Distribution and taxonomy of birds of the World. Yale University Press, New Haven, Connecticut.

 

Van Remsen, December 2003

 

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Comments from Robbins: "[YES] If Straneck, Ridgely, and Narosky state that the voice of Poospiza whitii and P. nigrorufa are quite different coupled with the obvious plumage differences I see no reason why we should not split these. I put more faith in this as a valid split than questionable published data such as presented for the Pterodroma proposal (#75)."

 

Comments from Stiles: "NO - again, published evidence required!"

 

Comments from Zimmer: "Another reluctant "NO". In cases like this I'm tempted to go with Mark, but the lack of any published analysis bothers me. Published qualitative descriptions of vocal differences would sway me more if we were talking about suboscines as opposed to oscines. Once again, I think a split is the correct treatment, but I'll wait for the published evidence."

 

Comments from Stotz: "YES. I agree with Mark's position. I remain unconvinced that we should wait for published details for obvious splits, with strong vocal differences and clear plumage differences."

 

Comments from Jaramillo: "YES. _ My fieldwork on cowbirds happened to coincide with the distribution of these two taxa (Buenos Aires, and Salta province in Argentina). The two taxa were quite different in the field, both in plumage and particularly in song. They also take different habitats, with whitii using dry thorny scrub, whereas nigrorufa takes woodland edge, riparian woodlands and shrubbery associated with marsh edge. I would consider nigrorufa to be somewhat associated with water, while whitii is not. Note that Straneck did include cuts of both of these taxa in his tape series on songs of the birds of Argentina. Having spent some time in the range of both of these creatures, I find it hard to think of them as anything other than two good species."

 

Comments from Nores: "NO, aunque por supuesto un No no muy definitivo. Yo quiero agregar una diferencia adicional que es que los jóvenes de ambas formas difieren substancialmente. En nigrorufa son pardo oscuro de arriba y acanelados de abajo con rayado en el pecho y flancos, sin rufo, mientras que en whitii los jóvenes son semejantes a los adultos, pero más pálidos y más rufescentes. El canto de whitii es más melodioso y complejo, pero para mí no demasiado diferente."