In the following we briefly analyze and compare voice of the three races of Masked Gnatcatcher (Polioptila dumicola). 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).
Races dumicola and saturata: Song is typically a series of notes, including at least in part a repetition of about the same notes or note pairs, at about constant pitch. Some examples (illustrated with multiple sonograms in the pdf version of this note).
Race berlepschi: Song is quite variable, typically a note series which rises or falls in pitch. Notes are similar-shaped, but are not necessarily exact repeats. Some examples.
There is a high variability in song of both groups. On average, berlepschi seems to have notes (or repeated note pairs) which cover a narrower frequency range, and the song phrase more often has a rising or falling pitch. There is however clearly overlap, and a more in depth statistical analysis would be needed to quantify more precisely differences in vocal parameters.
Based on the average differences mentioned above, we estimate the total vocal score to be about 1 + 1 = 2.
This note was finalized on 14th April 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: on281_masked_gnatcatcher.pdf