In the following we briefly analyze and compare voice of the different races of Black-crested Antshrike (Sakesphorus canadensis). 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).
Loudsong of Black-crested Antshrike is a series of notes, which accelerate and rise in pitch towards the end. Song shows little variation among the different races, with the exception of race pulchellus. Unlike other races, song of pulchellus decelerates and drops in pitch towards the end, terminating with some more nasal snarling notes.
Measurement of some basic parameters of the loudsong:
pulchellus (n=6) other races (n=8)
# notes 14-23 11-19
start freq. 1330-1520Hz 1450-1960Hz
end freq. 1015-1580Hz 2150-2810Hz
pace first notes 3.5 - 4.2 n/s 2.5 - 3.4 n/s
pace last notes 5.0 - 6.2 n/s 5.0 - 7.7 n/s
max. freq. 1660-1920Hz 2150-2810Hz
total length 3.20-4.55s 2.77-3.96s
freq. change last 4 notes -330Hz to -800Hz +0 to +575Hz
Song of pulchellus differs in its initial faster pace (score 2-3), lower start frequency (score 2), lower max. frequency (score 3), and last notes dropping in pitch (score 3-4) reaching a much lower end frequency (score 3), and with an overall lower acceleration (score 2-3).
Note shapes are also somewhat different, being rather uniform and symmetrical throughout the song phrase in pulchellus, while in other races note shape changes from slightly asymetrical at first to distinctly knife-shaped towards the end.
Above differences result in a total score for vocal difference of 6.
This note was finalized on 18th June 2015, 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: on52_black-crested_antshrike.pdf