Notes on the vocalizations of Chestnut-belted Gnateater (Conopophaga aurita)

In the following we briefly analyze and compare voice of the different races of Chestnut-belted Gnateater (Conopophaga aurita). 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).

Song of all races is a long trilled series of notes, and there seem to be two groups which are vocally distinct. We have measured some basic sound parameters:

Group 1: snethlageae/ pallida (n=4)

max. freq.                             3650-4300Hz

note length                           0.04-0.05s

pace                                      0.095-0.105 (measured as period,duration between 2 subsequent notes)

total length                          1.94-3.3s

intro notes                           no clear introductory notes, sometimes slightly dropping in pitch at start

Group 2: other races (australis, occidentalis, aurita, song from Palmari may be inexpectata?) (n=6)

max. freq.                             3200-4000Hz

note length                           0.026-0.035s

pace                                      0.054-0.06

total length                          1.7-4s

intro notes                           1-4 introductory notes which rise gradually in pitch at start

There is a clear difference between snethlageae/ pallida and other races: Song pace of both groups is remarkably stable, and is much slower in snethlageae/pallida (almost half the speed, score 3), with longer notes (score 2). Furthermore, there are no initial rising notes in the song of snethlageae/pallida. The latter possibly also slightly higher in frequency, but more samples needed, and score probably only 1.

If we consider pace and note length independent, than vocal difference leads to a quantified total score of 5.

This note was finalized on 13th May 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, Peter Boesman, Paul Coopmans, Sidnei Dante, David Geale, Frank Lambert, Dan Lane, Alexander Lees, Gabriel Leite, Curtis Marantz, Jeremy Minns, John V Moore, Otte Ottema, Andrew Spencer and Philip Stouffer.

References

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: on65_chestnut-belted_gnateater.pdf