Notes on the vocalizations of Ornate Antwren (Myrmotherula ornata)

In the following we briefly analyze and compare voice of the different races of Ornate Antwren (Myrmotherula ornata). We also try to quantify the extent of any vocal differences using the criteria proposed by Tobias et al. (2010), as a support for any taxonomic review. We have made use of sound recordings available on-line from Xeno Canto (XC).

Song of Ornate Antwren is a short high-pitched trill initiated with one or more longer notes. Some trills however lack these introductory notes, and it is not clear if these are 'short songs' or a vocalization with a different function. We have only measured what appeared to be 'full songs' with at least one longer introductory note, with the following results:

	hoffmannsi (n=5)	meridionalis/ atrogularis(n=5)	ornata/ saturata(n=4)
# of notes	9-21	13-24	11-13
length 1st note	0.08-0.1s	0.07-0.1s	0.08-0.1s
max. freq. in trill	6100-7700Hz	6400-7500Hz	6300-7000Hz
max. freq. lowest note	4100-5400Hz	5000-5900Hz	5400-5800Hz
fastest pace over 5 notes (s)	0.074-0.09	0.07-0.091	0.1-0.137
total length	0.86-1.6s	1.06-2.35s	1.34-2.03s
frequency drop in trill	1500-3300Hz	1200-1600Hz	800-1600Hz
number of long intro notes	1 (with typically frequency spike at start)	1 (with usually round overslurred shape)	2 with stuttering start

From the above, we can deduct that there are slight differences in voice of typical loudsongs:

hoffmannsi has the largest frequency drop towards the end of the trill (score 1 or 2) and has a single long introductory note with spiky shape (score 1)

ornata/saturata has typically a stuttering start to the trill with two long introductory notes (score 2) and a slower pace in the trill (score 1 or 2).

meridionalis/atrogularis has the single introductory note (although more rounded overslurred) from hoffmannsi but much less frequency drop, more like ornata/saturata.

All in all, it would seem that the typical loudsongs of the three groups are distinctive, with a score of about 2-3 each vs. both other groups.

 

This note was finalized on 4th May 2015, using sound recordings available on-line at that moment. We would like to thank in particular the sound recordists who placed their material on XC: Roger Ahlman, Nick Athanas, Peter Boesman, Guilherme Brito, Taylor Brooks, Eric DeFonso, David Geale, Niels Krabbe, Frank Lambert, Dan Lane, Gabriel Leite, Mitch Lysinger, Hans Matheve, Jeremy Minns, John V. Moore, Jonas Nilsson, Eduardo Patrial, Fabrice Schmitt, Andrew Spencer, Joseph Tobias and Nathalie Seddon , 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: on45_ornate_antwren.pdf