In the following we briefly analyze and compare voice of the different races of Bran-colored Flycatcher (Myiophobus fasciatus). 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).
There aren't that many recordings of dawn song available, and definitely not of all races. On the contrary, there are quite some recordings of day-time song available, a very typical and often heard long note followed by a trill. In the following I am analyzing only this day-time song.
There are clearly 3 vocal groups:
Group 1: M. f. fasciatus M. f. saturatus M. f. auriceps M. f. flammiceps (no recordings of M. f. furfurosus).
Length 1st note 0.14-0.21s
min. note length 0.05-0.07s
max. freq. 3600-4700Hz
freq. range 2000-2900Hz
max. pace 0.058-0.088
# of notes 7-18
min. freq. 1500-1820Hz
Group 2: M. f. crypterythrus (SW Colombia, W Ecuador and NW & N Peru)
Length 1st note 0.21-0.25s
min. note length 0.09-0.14s
max. freq. 7300-10800Hz
freq. range 4500-7900Hz
max. pace 0.12-0.20
# of notes 5-11
min. freq. 2400-2800Hz
Group 3: M. f. rufescens (W Peru and extreme N Chile)
Day-time song seems to be usually a duet, one bird emitting a trill without initial long note, the second bird uttering squeaky notes.
Length 1st note 0.05-0.06s ??
min. note length 0.04-0.05s
max. freq. 3050-4200Hz
freq. range 1150-2400Hz
max. pace 0.06-0.074
# of notes 11-32
min. freq. 1530-2200Hz
Day-time song of crypterythrus differs from all other races by having longer notes (score 2), reaching much higher frequencies (score 2-3) with a very large frequency range (score 2-3) and having a slower pace (score 2-3), which leads to a total vocal score of about 5 by applying Tobias criteria.
Compared to all other races, day-time song of rufescens is structurally quite different (and therefore difficult to score in direct comparison), with usually two birds in asynchronous duet (score 1-2), trill seemingly lacks an initial long note (score 1-2) and number of notes in trill on average higher (score 1-2). Total vocal score therefore at least 3.
Group 1 and 2 have a day-time song which is structurally very similar. Dawn song is structurally also similar, but again it would seem from available recordings that group 2 (crypterythrus) is higher-pitched, with notes typically above 3kHz, while in group 1 notes typically go down to minimum frequencies of c 2kHz.
This note was finalized on 2nd July 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.
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: on144_bran-colored_flycatcher.pdf