In the following we briefly analyze and compare voice of the three races of Two-banded Warbler (Basileuterus bivittatus). 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).
Our main interest is to compare the disjunct population of the tepuis (roraimae) with the Andean races. A comparison of song (illustrated with multiple sonograms in the pdf version of this note).
Song of both groups is clearly very different. roraimae has a song phrase with many more notes (score 2-3), with a trilled end reaching a much higher pace (score 3-4) and reaching higher frequencies (score 2-3). Other differences are the clearly different note shapes, with roraimae having very short staccato-like notes. Total vocal score about 6.
roraimae seems to have 2 variants of its song: a trilled end at about same pitch, and a trilled end which is sharply rising. It is not clear whether this is given by the same bird or rather a duet performed by two birds or a coupled pair.
This note was finalized on 27th June 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.
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: on376_two-banded_warbler.pdf