In the following we briefly analyze and compare voice of the different races of White-fringed Antwren (Formicivora grisea). 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) and Macaulay Library (ML).
The difference in vocalization between 'Northern' and 'Southern' White-fringed Antwren was e.g. discussed in Hilty (2003), but is decidedly more complex than suggested there.
In fact, all races have a comparable 'song' which consists of a single 'note', which is repeated for shorter or longer periods:
hondae: repeated note has the shape of a small letter 'n'
fumosa: repeated note has the shape of a small letter' n'
intermedia: repeated note has the shape of a small letter 'n' or 'h' (often only a few notes repeated)
orenocensis: repeated note has the shape of a small letter 'h'
tobagensis: repeated note has the shape of a small letter 'n'
rufiventris repeated 'note' has the shape of a very long 'h' and preceded by a short sharply downslurred note (inaudible by human ear)
grisea: repeated 'note' has the shape of a sharply falling line, barely recognizable as an 'h' and preceded by a short sharply downslurred note or more complex shape (inaudible by human ear)
when grouping the above taxa into two groups (Southern = rufiventris/grisea and Northern: other races) and combining data we get:
'Northern' White-fringed Antwren (n>10)
repeated note has the shape of a small letter 'n' or 'h'
'Southern' White-fringed Antwren (n>10)
repeated note has the shape of a sharply falling line, somewhat like an 'h' and preceded by a short sharply downslurred note or more complex shape (inaudible by human ear)
The main vocal differences between the two groups are thus frequency range and top frequency of repeated notes (score 2 or 3) and pace (score 1 or 2), leading to a total score of about 4.
Besides this 'song', there are other clear differences in voice. E.g., a very distinct vocalization is 'a long whistle followed by a trill'. This has been documented for hondae, intermedia and orenocensis, and would thus seem unique for 'Northern White-fringed Antwren'. Possibly there are more differences to be found when analyzing the complete vocabulary.
As a final remark, there is no info about albicincta, other than a description like 'repeated chup notes'
This note was finalized on 6th May 2015, using sound recordings available on-line at that moment. We would like to thank in particular the many sound recordists who placed their material on XC and ML.
Hilty, S.L. (2003) Birds of Venezuela. Princeton University Press & Christopher Helm, Princeton & London
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: on46_white-fringed_antwren.pdf