In the following we briefly analyze and compare voice of the different races of Thrush-like Antpitta (Myrmothera campanisona). 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).
Song of all races is structurally similar, but subcanescens clearly differs in a number of features (Fig. 1). We have therefore taken some measurements of the basic sound parameters to compare subcanescens with the other races treated as a single group:
max. note length 0.17-0.25s
max. mid freq. 1080-1220Hz
end freq. 1080-1220Hz
freq. change +60 to +140Hz
last note length 0.16-0.25s
# notes 5-9
highest amplitude last or last but one note
max. note length 0.18-0.28s
max. mid freq. 750-950Hz
end freq. 750-920Hz
freq. change -90 to +30Hz
last note length 0.15-0.24s
# notes 6-10
highest amplitude fourth, third or second last note
Song of subcanescens is clearly higher-pitched (score 3) and rises towards the end (score 2). Furthermore, the max. amplitude is reached on the last or last but one note (score 1-2). Also the last note of the song does not become shorter, which is often the case in other races.
From the other races, dissors seems to have the highest pitch (XC163576 is probably not modesta but also dissors), but still clearly lower than subcanescens, and lacking the other features of subcanescens.
Total score for vocal difference between subcanescens and other races is thus 4-5.
This note was finalized on 15th 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: on74_thrush-like_antpitta.pdf