In the following we briefly analyze and compare voice of the two races of White-throated Greenbul (Phyllastrephus albigularis). 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). Furthermore, Michael Mills generously passed on own information and recordings of the race viridiceps from Angola, indicating its distinctiveness.
A comparison of both races (illustrated with multiple sonograms in the pdf version of this note):
* a rhythmic "whup..whup..nyeeh" repeated without pause, the 3rd note distinctly nasal and slightly longer
* possibly song: a repeated melodious trisyllabic note "pu-puh-weeh!"
* several short nasal scolding notes, given single or in series
* presumed song is a repeated burry single note "rreeh.....rreeh...." or "prrew...prrew..."
* most common calls are short guttural notes (actually short rattles of 2 or more notes) "grr-grr.." or "drrr" etc.
* scolding or alarm call
* excitement call
The above quite convincingly illustrates that both taxa have a fundamentally different vocabulary. viridiceps differs in having principally nasal overslurred contact calls (vs guttural rattled calls for albigularis)(e.g. based on bandwidth of fundamental frequency, score 2-3) . Presumed song is a repeated trisyllabic melodious note "pu-puh-weeh!" (vs a variable very burry single note for albigularis)(e.g. based on number of notes, score 2-3). Application of Tobias criteria would lead to a total vocal score of about 5. While the vocal differences are quite convincing, the conclusions would obviously benefit from additional recordings of race viridiceps, in order to get a better understanding of the full vocabulary of this taxon.
This note was finalized on 12th July 2016, using sound recordings available on-line at that moment. We would like to thank the sound recordists who placed their recordings for this species on XC and ML: Josh Engel, David Moyer and Martin St-Michel, and in particular Michael Mills for recordings of viridiceps.
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: on407_white-throated_greenbul.pdf