Notes on the vocalizations of Dull-colored Grassquit (Tiaris obscurus)

In the following we briefly analyze and compare voice of the different races of Dull-colored Grassquit (Tiaris obscurus). 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).

An overview of song per region (illustrated with multiple sonograms in the pdf version of this note): N Venezuela, Santa Marta, C Colombia, Ecuador (N to S), Peru (N to S), Bolivia, Argentina.

From the above examples, it is quite clear that song over its entire range is very similar: a short (c 1s) high-pitched warbled phrase with a sizzling tonal quality. There are no clear vocal differences among groups, given there is quite some variation within each region. A much larger set of recordings would be needed to determine whether there are notes or phrases which are truly unique to certain groups. It is unlikely however this will lead to a high score for vocal difference.

This note was finalized on 4th July 2016, 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: Roger Ahlman, Nick Athanas, Peter Boesman, Miguel Castelino, Jerome Fischer, David Geale, Bennett Hennessey, Sebastian Herzog, Niels Krabbe, Bernabe Lopez Lanus, Oscar Marin Gomez, Hans Matheve, John V Moore, Leonardo Ordoñez Delgado, Raul Spais and Andrew Spencer, Martin St Michel, Joseph Tobias and Herman Van Oosten.

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: on401_dull-colored_grassquit.pdf