In the following we briefly analyze and compare song of the different races of Olive-striped Flycatcher (Mionectes olivaceus). 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).
M. o. olivaceus (E Costa Rica and W Panama): Song is a peculiar high-pitched (seemingly) continuous note going up and down in pitch. Inaudible to the human ear, this continuous note is in fact a chain of very short notes (c. 0.03-0.04s long).
max. freq. 10.000-11.600Hz
min. freq. 8000-8600Hz
note length 3.9-7.9s (consisting of a long chain of notes c. 0.035s long)
pause (between the short notes pauses are hardly measurable, c. 0.01s)
M. o. hederaceus (Panama (E from Veraguas), N & W Colombia (Cauca Valley, W slope and lowlands) and W Ecuador (S to Loja)): Song is a long regular series of high-pitched notes which go up and down in pitch (typically 2 notes up and 2 notes down, ABCBABCBA.., sometimes more). Note shape is very constant, a curly S-shape.
max. freq. 9500-11000Hz
min. freq. 7700-9000Hz
note length 0.24-0.35s
pitch change 600-1300Hz
M. o. galbinus (Santa Marta region of N Colombia): We only have one recording of this taxon. Song is long irregular series of high-pitched notes which go up and down in pitch without clear pattern. Note shape is irregular. Shows some similarity with previous race, but very irregular.
max. freq. 10700Hz
min. freq. 7400Hz
note length 0.30-0.43s
pitch change 1100Hz
M. o. venezuelensis (N Venezuela and S along E base of Andes to S Colombia; also Trinidad) and M. o. fasciaticollis (E base of Andes from S Colombia S to S Peru and extreme N Bolivia): Song is a high-pitched phrase which is endlessly repeated. This phrase is identical for 2 available recordings of the Venezuelan Andes, very similar for the E Andes in Ecuador and Peru, and somewhat different for one available recording from NE Venezuela (presumably as a result of disjunct range prohibiting gene-flow, evolving into distinct taxon).
max. freq. 9400-11200Hz
min. freq. 6800-7800Hz
note length 0.52-0.98s
pitch change 0-100Hz
If we cluster hederaceus and galbinus, we can distinguish 3 groups with very different song:
M. o. olivaceus has extremely short notes (score 4 vs. all others) at an extremely rapid pace (score 4 vs. all others) going up and down in pitch. If we apply Tobias criteria and consider note length and pace independent, this leads to a total vocal score of 8 vs. other groups.
The song abruptly changes in W Panama from Chiriqui (olivaceus) to W Panama state (hederaceus)
hederaceus/galbinus differs from venezuelensis/fasciaticollis in having medium length notes (score 2-3) going up and down in pitch (score 3-4), while the latter has longer notes with a broad frequency range, always repeated at same pitch. Total vocal score about 6.
This note was finalized on 18th August 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: Roger Ahlman, Ken Allaire, Nick Athanas, David Bradley, Peter Boesman, Tayler Brooks, Paul Coopmans, Richard Hoyer, Niels Krabbe, Oscar Marin, Thore Noernberg, Ted Parker, Mark Robbins, David Ross, Andrew Spencer, Patricio Valenzuela and James Zook.
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: on117_olive-striped_flycatcher.pdf