In the following we briefly analyze and compare voice of the three races of Tit-like Dacnis (Xenodacnis parina). 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).
A comparison of song per race (illustrated with sonograms in the pdf version of this note): Ecuador (race petersi/bella ?), race bella, race petersi and nominate.
Song of petersi and bella is a sequence of some 5-10 clear whistles, typically one or more series of repeated identical notes, which are either sharply upslurred or downslurred. Most notes reach max. frequencies of 8-10kHz.
All but one recording of nominate are very different from northern races, song having mainly peculiar subdued lower-pitched bubbling notes at a much higher trilled pace. This would seem a major vocal difference, but then there is a single recording from Arequipa (ML33844 from Ted Parker), which is about identical to examples from Ecuador (!). This greatly reduces the marked vocal difference, but nevertheless, it would seem that the most commonly uttered song-type of nominate is very different from any vocalization known from northern races. Based on high pace and high number of notes, a 2+2 score could be given (albeit with some reservation, as there may be two song-types involved).
This note was finalized on 30th 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 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: on393_tit-like_dacnis.pdf