In the following we briefly analyze and compare voice of the different races of Scarlet-bellied Mountain-tanager (Anisognathus igniventris). We also try to quantify the extent of any vocal differences using the criteria proposed by Tobias et al. (2010), as a support for taxonomic review. We have made use of sound recordings available on-line from Xeno Canto (XC) and Macaulay Library (ML).
An overview of song per race (illustrated with multiple sonograms in the pdf version of this note):
lunulatus (Andes of W Venezuela (S Táchira) and adjacent Colombia (Norte de Santander S in E Andes to Cundinamarca)
erythrotus (C Andes of Colombia (Caldas, Cauca, Huila, and both slopes in Nariño) S through Ecuador to N Peru (N of R Marañón, S to R Chamaya)
ignicrissa (E slope of Andes of Peru S of R Marañón (C Cajamarca S of R Chamaya, and from Amazonas S to Junín)
igniventris (E slope of Peru (from Junín) S to Bolivia (Santa Cruz)
Song of igniventris is very different, being much higher pitched (most energy in range 5-10kHz vs below 6kHz in other races, score 3 based on max. frequency) and lacking nasal or twangy notes (score 1). Application of Tobias criteria would lead to a total score of about 4.
The change in song occurs in Junín, Peru, with apparently a narrow 'hybrid zone' NE of Huancayo: XC152904 is rather an intermediate song, ML171867 has elements of both song-types, ML92123 is a rather typical igniventris song, fFurther north and south there are no intermediate song types.
This note was finalized on 5th July 2016, using sound recordings available on-line at that moment. We would like to thank in particular the many sound recordists who placed their recordings for this species on XC and ML.
Tobias, J.A., Seddon, N., Spottiswoode, C.N., Pilgrim, J.D., Fishpool, L.D.C. & Collar, N.J. (2010). Quantitative criteria for species delimitation. Ibis 152(4): 724–746.
More Information: on404_scarlet-bellied_mountain-tanager.pdf