Notes on the vocalizations of Elegant Mourner (Laniisoma elegans)

In the following we briefly analyze and compare voice of the different races of Elegant Mourner (Laniisoma elegans). 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 both groups (Andean and Atlantic) is similar, a series of high-pitched underslurred whistles.

There are however some obvious differences, for which we have measured a number of basic sound parameters:

Andean group (only recordings of buckleyi !!)(n=9)

# notes                                                 5-8

total length                                          10-16s

max. note length                                 1.07-1.3s

lowest freq.                                         4700-5600Hz

highest freq.                                        6400-7200Hz

max freq. range 1 note                      1000-1400Hz

Atlantic group (elegans) (n=8)

# notes                                                 8-15

total length                                          11-22s

max. note length                                 0.65-0.9s

lowest freq.                                         3400-4500Hz

highest freq.                                        5200-7000Hz

max freq. range 1 note                      1300-2400Hz

From the above measurements, it is clear that song of Andean group has fewer notes (score 1-2) longer in duration (score 2-3), which don't go as low in frequency (score 1-2) and thus frequency range of single notes is smaller (score 1-2). When applying Tobias criteria, the total score for vocal differences is about 4.

This note was finalized on 10th June 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, Rodrigo de la Rosa, Ricardo Gagliardi, Niels Krabbe, Bernardo Lacombe, Jeremy Minns, John V Moore, Jonas Nilsson, Ted Parker, Eduardo Patrial,  Leonardo Pimentel, Glenn Seeholzer and Charlie Vogt.

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: on114_elegant_mourner.pdf