In the following we briefly analyze and compare voice of the three races of White-browed Bush-robin (Tarsiger indicus). 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 voice of disjunct race formosanus from Taiwan with the two mainland races. Song is a short mellow phrase at stable pitch. A comparison per race (illustrated with multiple sonograms in the pdf version of this note): formosanus, yunnanensis and indicus.
Differences among races are minor at most, and basic sound parameters (phrase length, note duration, min./max. frequency,...) all very similar. yunnanensis possibly slightly lower-pitched. formosanus very similar to indicus, possibly using on average slightly longer notes and longer pauses between notes. Main call note, a rising 'wheet' also very similar between races formosanus and indicus.
We can thus conclude that formosanus is not particularly different in voice from mainland races.
This note was finalized on 11th May 2016, using sound recordings available on-line at that moment. We would like to thank in particular the sound recordists who placed their recordings for this species on XC: Marc Anderson, Nick Athanas, Niels Poul Dreyer, David Ewards, Ko Chie-Jen, David Farrow, Frank Lambert, Arnold Meijer, Mike Nelson, Mathias Ritschard, Cynthia Su and Yong Ding Li.
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: on327_white-browed_bush-robin.pdf