Notes on the vocalizations of Wing-banded Antbird (Myrmornis torquata)

In the following we briefly analyze and compare voice of the two races of Wing-banded Antbird (Myrmornis torquata). 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).

The song, a rising and slightly accelerating series of loud notes, is quite variable in duration, pace and number of notes, even within every region. It is unclear whether this is mainly induced by playback or not. There are however some characters which allow to distinguish birds from the four main regions as grouped in the following and illustrated in Fig. 1:

stictoptera Central America (n=8)

Av. note length                    0.15-0.22s

pace at start                         0.3-0.4 (measured here as period, duration between 2 subsequent notes)

pace at end                          0.24-0.39

max. freq. first note            2300-3100Hz

max. freq. last note             3750-4700Hz

freq. range                           1400-2400Hz

note shape                           a hooked rising shape (unlike torquata)

torquata  E Ecuador region (n=3)

Av. note length                    0.27-0.31s

pace at start                         0.43-0.48

pace at end                          0.32-0.4

max. freq. first note            2450-2700Hz

max. freq. last note             3100-3600Hz

freq. range                           1300-1800Hz

note shape                           a sharp overslurred note, like a reverse 'V'

torquata  Guianan region (N of Amazon) (n=6)

Av. note length                    0.2-0.25s

pace at start                         0.32-0.38

pace at end                          0.29-0.34

max. freq. first note            2200-2600Hz

max. freq. last note             3100-3800Hz

freq. range                           2000-2300Hz

note shape                           a sharp overslurred note, like a reverse 'V' (but first leg slightly bended)

torquata S of Amazon (n=6)

Av. note length                    0.16-0.52s

pace at start                         0.3-0.65

pace at end                          0.27-0.58

max. freq. first note            2600-3200Hz

max. freq. last note             3600-4350Hz

freq. range                           2400-3000Hz

note shape                           a double-peak note, the first peak shorter and much lower-pitched (also clearly audible), the second peak rounded

 

Every of the four groups can be distinguished easily by note shape alone (with birds from E Ecuador and Guianas having the most subtle difference and stictopera being the most different one). Furthermore, stictopera seems to have the shortest notes (although one recording from S of Amazon has also very short notes, this however after playback). stictopera also reaches the highest frequencies, although birds S of the Amazon get almost equally high. These three minor differences could all be given a score 1.

The total vocal score of stictopera vs torquata (3 regions combined) thus is about 2, or a rather small vocal difference.

This note was finalized on 12th 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: Ken Allaire, Peter Boesman, Allen Chartier,Bradley Davis, Jon King, Gabriel Leite, Linda Macaulay, Hans Matheve, Jeremy Minns, Ted Parker, Eduardo Patrial, Alexandre Renaudier and Andrew Spencer.

 

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: on63_wing-banded_antbird.pdf