Proposal (138) to South American Classification Committee
Recognize Amazilia alticola as a species distinct from A. amazilia
Alticola was described as a species by Gould (1860) and was so considered by Cory (1918), along with dumerilii and leucophaea, currently considered subspecies of A. amazilia. Chapman (1926) analyzed geographic variation in this group and lumped alticola, dumerilii and leucophaea into A. amazilia. He noted confusion with respect to type localities of some forms, and cited specimens intermediate between alticola and dumerilii from SW Ecuador.
Peters (1945) lumped all forms into A. amazilia, as had Chapman. Zimmer (1950) analyzed a larger series and came to essentially the same conclusion, i.e. that all were races of A. amazilia. He noted great variation in the extent of white coloration below in SW Ecuador, increase in size with elevation in the group, individual variation and apparent introgression of alticola characters into some populations of dumerilii and leucophaea. Meyer de Schauensee (1966) maintained all as races of A. amazilia, as did Sibley & Monroe (1990).
Weller (2000) split A. alticola as a separate species based upon presumed habitat differences, parapatry without interbreeding and vocal repertoires. Description of habitats suggests that separation might not be complete, and his interpretations of habitats and parapatry were apparently based entirely upon specimen data as he did not mention field work; in no place are the vocal differences specified, and the possibility of song dialects was not considered. Color variation considered by Chapman and Zimmer as introgression was interpreted by Weller to represent individual variation, though the rationale was not entirely clear. Weller cited significant differences in size between alticola and other forms, though he did not separate subsamples geographically to check for trends. He presented a "biogeography and speciation model" to explain and support his interpretation, but this was based more upon subjective interpretations of plumage coloration than hard data: genetic data were lacking. Schuchmann (1999) anticipated Weller's publication in splitting alticola in HBW vol. 5.
Finally, Ridgely & Greenfield (2001) did not accept Weller's split, citing a probable undescribed taxon in SW Ecuador (where Zimmer had noted great variation in coloration). As these authors have presumably had much field experience in the region and Ridgely had analyzed specimens, their recommendation for caution in recognizing alticola merits serious consideration: the situation may well be more complicated than Weller's analysis suggests, especially as some key differences adduced by Weller (voice, habitat) were evidently not observed by him directly.
Because the situation clearly merits further work, I recommend a NO vote on this proposal pending a thorough analysis including field and genetic studies.
Gould 1861, PZSL
Cory 1918, Catalogue of Birds of the Americas, Part II no. 1.
Chapman 1926, Distribution of bird-life in Ecuador. Bull. AMNH
Peters 1945, Checklist of birds of the world, vol. 5
ZIMMER, J. 1950e. Studies of Peruvian birds, No. 59. The genera Polytmus, Leucippus, and Amazilia. American Museum Novitates 1475: 1-27.
Meyer de Schauensee 1966, The Species of Birds of South America
Sibley & Monroe 1990, Distribution and Taxonomy of Birds of the World
Schuchmann 1999, Handbook of Birds of the World, vol. 5
WELLER, A.-A. 2000b. Biogeography, geographic variation, and habitat preferences in the Amazilia Hummingbird, Amazilia amazilia Lesson (Aves: Trochilidae), with notes on the status of Amazilia alticola Gould. J. Ornithol. 141: 93-101.
& Greenfield 2001, Birds of Ecuador.
Gary Stiles, November 2004
Comments from Remsen: "NO. Gary makes excellent points about Weller's paper; this one sounds as if more work is definitely needed."
Comments from Pacheco: "NO. Diante dos argumentos reunidos por Stiles, acho acertado manter o táxon alticola subordinado a A. amazilia até que melhor informação esteja disponível."
Comments from Jaramillo: "NO. This sounds very confusing, even if Weller is right he did not provide the data which will convince that his conclusion has merit."
Comments from Nores: "NO, definitivamente. Las razones dadas por Weller tienen para mi muy poco fundamento. Además, las diferencias en plumaje de alticola con A. a. dumerilii son para mí sólo subespecíficas. De todos modos, existen tres grupos diferentes en cuanto al color (especialmente los tres de garganta blanca), que podría corresponder a tres especies distintas: A. a. amazilia, A. a. caeruleogularis y A. a. dumerilii/leucophaea/alticola."
Comments from Zimmer: "NO. More fieldwork is clearly needed. There are some instances where chopping away at a complex problem in piecemeal fashion is preferred over waiting for an overall review, but I don't think this is one of them."