Proposal (33) to South American Classification Committee

 

Lump Cinclodes taczanowskii and C. nigrofumosus

 

Effect on South American CL: This proposal would lump two species currently recognized as separate species on our baseline list.

 

Background: For most of their history, taczanowskii and nigrofumosus have been recognized as sister taxa. They are allopatric (nearly parapatric) taxa with no known contact zone; taczanowskii is endemic to coastal Peru, and nigrofumosus, endemic to coastal Chile. No data published data exist on characters directly relevant to assessing potential interbreeding such as vocalizations. They are (presumably) 100% diagnosable phenotypic units based on plumage characters. The primary differences in plumage are (apparent) degree of pigment saturation, with taczanowskii paler overall. The only pattern differences are not "quantum" but a matter of degree: less conspicuous superciliary and reduced breast spotting in taczanowskii. (If the Peruvian coastal environment were "paler" overall than that of Chile, then this would be an example of Gloger's Rule variation.)

 

Cory & Hellmayr (1925) considered these two taxa as separate species, but noted that taczanowskii was "probably a northern race of nigrofumosus". Peters (1951) maintained them as separate species (somewhat surprising giving the several novel lumps of species-level taxa in that treatment). Meyer de Schauensee (1966, 1970) considered them conspecific, without providing any rationale. Vaurie (1980) and Sibley & Monroe (1990) treated them as separate species. Ridgely & Tudor (1994) also considered them as separate species and noted that their ranges are allopatric by no more than 70 km, and noted that no signs of intergradation have been detected. Remsen (2003) maintained them as separate species but noted that evidence for this is weak, but no worse than for species-level treatment of several other taxa in Cinclodes (e.g., CaricomaeC. olrogi, and C. comechingonus).

 

Analysis: This problem is like perhaps several hundred others in South America with respect to species-ranking of allopatric sister taxa: we don't have enough data to make a sound decision one way or another, but we need to deal with them. It would be reasonably easy to obtain vocal data on these and other Cinclodes to do an analysis following the protocols established by Isler, Isler, & Whitney (1998), but that's for the future. The plumage differences are not really much more than that shown among several subspecies of C. fuscus, but they are also of the same magnitude as those among the taxa ranked as species noted above.

 

Recommendation: I will vote "NO" on this proposal because in the absence of data, I see no reason to change our current classification, which uses narrowly defined species limits in Cinclodes. Perhaps when we have real data on one or two of these "borderline" cases, we can apply those results to this one if no more direct data become available in the meantime.

 

Literature Cited:

 

CORY, C. B., AND C. E. HELLMAYR. 1925. Catalogue of birds of the Americas Field Mus. Nat. Hist. Publ., Zool. Ser., vol. 13, pt. 4.

ISLER, M. L., P. R. ISLER, & B. M. WHITNEY. 1998. Use of vocalizations to establish species limits in antbirds (Passeriformes: Thamnophilidae). Auk 115: 577-590.

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.

PETERS, J. L. 1951. Check-list of birds of the world, vol. 7. Museum of Comparative Zoology, Cambridge, Massachusetts.

REMSEN, J. V., JR. 2003 (in press). Family Furnariidae (ovenbirds). Pp. #-# in "Handbook of the Birds of the World," Vol. 8. Broadbills to Tapaculos (del Hoyo, J. et al., eds.). Lynx Edicions, Barcelona.

RIDGELY, R. S., AND G. TUDOR. 1994. The birds of South America, vol. 2. 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.

VAURIE, C. 1980. Taxonomy and geographical distribution of the Furnariidae (Aves, Passeriformes). Bulletin of the American Museum of Natural History 166: 1-357.

 

Van Remsen, July 2003 

 

P.S.: If the proposal does not pass, then I'll work on another one on the English names of these two.

 

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Comments from Schulenberg: "My vote: "No". I haven't seen a taczanowskii in the flesh in a while now, and we don't have many specimens of it. But in addition to being paler and less spotted below, I thought that it had a "dingy" throat. Nigrofumosus, on the other hand, has a very white throat contrasting with the darker body. I'm impressed that two such different looking taxa so closely approach one another without (known) introgression. That said, earlier this year Alvaro Jaramillo saw a bird in northern Chile that threw him: it either was a taczanowskii (which would be a new record for Chile) or was something intermediate. Of course, n = 1 for intermediates or hybrids does not make much of a case for lumping either. But I'll be interested to see Alvaro's comments on this proposal. "

 

Comments from Robbins: "NO, mostly as a result of historical treatment; obviously we need vocalizations of these two taxa to really understand what is going on."

 

Comments from Stotz: "I vote to keep the two Cinclodes separate, although the evidence is weak, based on close approach without intergradation. Status quo helps here too."

 

Comments from Zimmer: "I vote "no" on proposal to lump Cinclodes taczanowskii and C. nigrofumosus, primarily on the basis that there is no published rationale to support the change. Tom's points concerning the close approach without apparent intergradation, and the distinction in throat color are also well-taken."

 

Comments from Stiles: "NO (until evidence is published)."

 

Comments from Silva: "We need more evidence to make this change."

 

Comments from Jaramillo: "NO. There certainly is a need to compare vocalizations of these two Cinclodes, and all Cinclodes for that matter. I had thought that a couple of birds I saw in Arica, northernmost Chile were taczanowskii-like while in the field. After looking at photos of taczanowskii, I haven't been able to see skins recently, it was clear to me that the birds I saw were nigrofumosus, and not intermediate at all. The Arica birds may be a little paler on the upperparts and underparts than more southern nigrofumosus, but in other features do not resemble taczanowskii at all. The Arica birds had bold and bright white throats, and supercilia, as well as cinnamon wing stripes. Skins and photos of taczanowskii I have seen show pale buff wing stripes, buffy or brownish supercilia, and no clear white throat patch. There are also differences in tail pattern, and distinctness of underpart streaking, the bold streaking of the Arica birds is consistent with nigrofumosus again, not taczanowskii. So in terms of physical appearance, perhaps there is a cline within nigrofumosus, with northern birds being paler than southern birds, but so far no sign of intermediate populations between nigrofumosus and taczanowskii. In fact, the white supercilia of the Arica birds was more extensive than on more southern nigrofumosus, so in this feature alone the northern Chilean birds are actually less like the nearby taczanowskii than expected due to geographic proximity. Keep in mind that these observations are based on a pair of birds only. Individuals of nigrofumosus I have seen in Iquique a bit to the south did not strike me as anything other than pretty typical nigrofumosus. In conclusion, my field observations from Arica don't suggest there is an intermediate population here. Arica is a key site as it is where the northernmost rocky habitat is found in Chile, and both of these Cinclodes are restricted to rocky coastal habitats. North of Arica there are many, many miles of sand beaches without rocky outcroppings. I think it is at least 40 km or more of beach, and this is certainly the ecological separation between these two taxa. It would be interesting to study skins, if they exist, of the southernmost Peruvian population. My guess is that there will be no tendency towards intermediacy. As such, I am comfortable retaining these two taxa as separate species until intermediates are found, or vocal or molecular data suggests otherwise. Note that plumage differences between many good species in Cinclodes (sympatric ones like oustaleti, C. fuscus fuscus, patagonicus, or C. fuscus albiventris and atacamensis) are slight to moderate. In many cases they are less distinct than the plumage differences between taczanowskii and nigrofumosus. I think that this is a more valid comparison than comparing to differences in plumage within fuscus, as almost surely those well-marked subspecies are good species. I have been slowly collecting recordings of C. fuscus fuscus, and C. fuscus albiventris. An even more limited data set I have suggests that northernmost albidiventris is another diagnosable group, based on vocalizations. That is a proposal for the future, when I have more data."