Notes on the vocalizations of Rufous-winged Antwren (Herpsilochmus rufimarginatus)

In the following we briefly analyze and compare voice of the different races of Rufous-winged Antwren (Herpsilochmus rufimarginatus). 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).

Loudsong is a stuttering series of notes, accelerating towards the end. We have made a number of measurements for the basic sound parameters of this loudsong:

exiguus (n=3)

total length                           1.2 - 1.5s

# of notes                             29-30

initial pace                           0.08-0.09 (here measured as period, duration between 2 subsequent notes)

average pace                        0.047-0.052

start max. freq.                    2040-2300Hz

max. freq.                            2160-2420Hz

initial freq. rise                    80-160Hz

 

frater (n=6)

total length                           1.3 - 1.9s

# of notes                             20-35

initial pace                           0.09-0.13

average pace                        0.046-0.074

start max. freq.                    2000-2300Hz

max. freq.                            2090-2380Hz

initial freq. rise                    80-150Hz

 

scapularis (n=4)

total length                           1.4 - 1.7s

# of notes                             25-34

initial pace                           0.08-0.10

average pace                        0.05-0.056

start max. freq.                    1850-2070Hz

max. freq.                            1920-2140Hz

initial freq. rise                    20-90Hz

 

rufimarginatus (n=10)

total length                           1.57-1.95s

# of notes                             16-23

initial pace                           0.17-0.23

average pace                        0.082-0.103

start max. freq.                    2070-2620Hz

max. freq.                            2570-3180Hz

initial freq. rise                    170-550Hz

 

Song of all races is very similar except nominate race. Race scapularis of NE Brazil surprisingly is in the same group as frater and exiguus. This is assuming that scapularis occurs only south to S Alagoas, while birds further south are nominate (different from HBW Vol. 8 !).

It is clear from the above measured parameters that race rufimarginatus differs in many ways:

song initiates with typically 3 slow-paced notes (score 3-4) which rise in frequency (score 2) reaching a higher frequency than other races (score 3), after which a low number of fast notes gradually decelerate. Total number of notes is lower (score 1-2) and overall song length is marginally longer, resulting in a much lower average pace (score 2-3).

Also, song of other races switches halfway to much more scratchy notes.

Furthermore, call seems to differ significantly as well, with nominate typically uttering short series of 2-5 mellow notes repeatedly.

We can conclude that vocal differences of race rufimarginatus vs. all other races are significant, leading to a total score of about 6.

At the other hand, differences between the 3 other races are minimal, with almost all data ranges overlapping. Score at most 1+1.

This note was finalized on 18th June 2015, using sound recordings available on-line at that moment. We would like to thank in particular the many sound recordists who placed their recordings for this species on XC.

 

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.

Zimmer, K., Isler, M.L. (2003). Rufous-winged Antwren (Herpsilochmus rufimarginatus). In: del Hoyo, J., Elliott, A., Christie, D.A. (eds.). Handbook of the Birds of the World Vol. 8. Broadbills to Tapaculos. Lynx Edicions, Barcelona.

More Information: on50_rufous-winged_antwren.pdf