In the following we briefly analyze and compare voice of the different races of Grey-headed Bullfinch (Pyrrhula erythaca). 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).
True song is apparently rarely heard, a rather fast-paced jumbled song, sometimes ending with some pure whistles (nominate).
Most available recordings are however of the commonly-heard mellow whistles (usually doubled, but also single, tripled etc.) (illustrated with multiple sonograms in the pdf version of this note):
erythaca: The majority of recordings from China have a second (and occasionally third/fourth) note that is higher-pitched than the first one. Most recordings from India however have double notes at very similar pitch or slightly falling.
owstoni: All available recordings from Taiwan have a second note which is lower in pitch than the first one.
Sometimes, slightly longer series of whistles are given in both erythaca and owstoni.
All basic sound parameters of vocalizations of both races are very similar, with considerable overlap. owstoni reaches on average slightly lower frequencies (1), and occasionally has longer notes (1). The main distinguishing feature by ear is the subsequent notes dropping in pitch (although in some cases, birds from India are very similar) (1-2).
We haven't found any recordings of true song from Taiwan and no recordings at all of race wilderi.
We can conclude that based on available recordings there is seemingly a vocal difference in the whistled note vocalization between nominate and owstoni, which is however rather minor. When more recordings become available of all races, including of true song, it is recommended to perform a more in depth analysis.
This note was finalized on 30th October 2015, 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 and ML: Nick Athanas, Mike Catsis, Chie-Jen Ko, Ben King, Frank Lambert, Mike Nelson, Sheldon Severinghaus and Tsai-Yu Wu.
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: on354_grey-headed_bullfinch.pdf