Proposal (68) to South American Classification Committee
Treat Basileuterus chlorophrys as separate species from B. chrysogaster
Effect on South American CL: This proposal would split our Basileuterus chrysogaster into two species, with recognition of northern chlorophrys as a separate species.
Background: The bird we treat as one species, Basileuterus chrysogaster (Golden-bellied Warbler), has a disjunct distribution, with the subspecies chlorophrys in the Western Andes from central Colombia to central Ecuador, and the other in the Eastern Andes from central to southern Peru. This follows the traditional classification (e.g., Hellmayr 1935, Meyer de Schauensee 1966, 1970, Lowery & Monroe 1968, Meyer de Schauensee & Phelps 1978, Hilty & Brown 1986, Ridgely & Tudor 1989, Curson et al. 1994, Sibley & Monroe 1990).
The subspecies chlorophrys is very similar in plumage to nominate chrysogaster, differing primarily in having a mostly olive, not yellow, superciliary, with the yellow restricted to anterior-most portion.
New information: Ridgely & Greenfield (2001) treated chlorophrys as a separate species, with the note that its song is "utterly different" from nominate chrysogaster. The qualitative description of the song is "a very thin , wiry, buzzy 't-t-t-t-tzzzzzzzzzzzzz" (same description as in Ridgely & Tudor 1989). However, I can't find a published description of the song of nominate chrysogaster. (I'm sure it exists on one or more published CDs and perhaps in published literature.)
Analysis: The plumage differences between chlorophrys and chrysogaster are less, in many cases far less, than those between many taxa currently treated as same subspecies in Basileuterus. The vocal differences are more weakly documented than in previous parulid proposals in which vocal differences were part of the argument. I'm sure that Bob and others are right about the degree of difference between chlorophrys and chrysogaster, but without formal published documentation, sonograms, etc., I cannot evaluate the evidence.
Recommendation: I vote "NO" on this proposal. A published, quantitative analysis of differences in song is what I need to be convinced on this one.
CURSON, J., D. QUINN, AND D. BEADLE. 1994. Warblers of the Americas. Houghton Mifflin.
HELLMAYR, C. E. 1935. Catalogue of birds of the Americas. Field Mus. Nat. Hist. Publ., Zool. Ser., vol. 13., pt. 8.
HILTY, S. L., AND W. L. BROWN. 1986. A guide to the birds of Colombia. Princeton University Press, Princeton, New Jersey.
LOWERY, G. H., JR., AND B. L. MONROE, JR. 1968. Family Parulidae. Pp. 3-93 in "Check-list of birds of the World, Vol. 14" (Paynter R. A., Jr., ed.). Museum of Comparative Zoology, Cambridge, Massachusetts.
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.
RIDGELY, R. S., AND P. J. GREENFIELD. 2001. The birds of Ecuador. Vol. II. Field guide. Cornell University Press, Ithaca, New York.
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, October 2003
Comments from Stotz: "No. May be inconsistent with my vote on the restarts, but the vocal descriptions are weaker and the biogeographic pattern is not as distinctive."
Comments from Jaramillo: "NO -- need more data, particularly published data."
Comments from Zimmer: "I vote "NO", for same reasons outlined in previous proposal."
Comments from Stiles: "NO for the same reasons [as in Prop 67]."
Comments from Nores: "NO. Por las mismas razones que la propuesta # 67."