In the following we briefly analyze and compare voice of the different races of Rufous-naped Wren (Campylorhynchus rufinucha). 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).
Voice of the three groups has been studied extensively in Sosa-López et al. (2013), and examination of the available on-line recordings confirms their findings (illustrated with sonograms in the pdf version of this note).
capistratus duets with both birds uttering low-pitched melodious whistles of comparable shape, in perfect synchrony.
rufinucha duets with both birds uttering quite different notes but in perfect synchrony.
humilis duets with one bird emiting well-spaced melodious notes and the other bird chattering at a very different pace, asynchronous.
To apply Tobias criteria, we need to identify a number of quantifiable differences:
- the pace (period) with which the same note is repeated is much slower in capistratus (c. 1.5-2s interval) vs. less than 1s in other 2 groups.
- the total phrase of notes which is repeated consists of 3-4 notes in capistratus, 2 notes in rufinucha and a much higher number in humilis if the chattering of the 2nd bird is included.
Without digging deeper into the topic, it is clear that the three groups differ vocally in a number of ways.
capistratus differs from rufinucha by duet phrases including more notes (2) which are all of a similar type (while both sexes of rufinucha utter very different notes, score 1-2) and which have a longer period duration (score 2-3).
capistratus differs from humilis by duet phrases including less notes (2) which are all of a similar type (while both sexes of humilis utter very different notes, score 1-2), which are given in synchronous duet (2) and which have a longer period duration (score 2-3).
rufinucha differs from humilis by a synchronous duet (2) with only two notes per period (vs. many more in humilis, score 3).
When applying Tobias criteria, this would lead to total vocal score of at least 4 for each pair-wise comparison.
This note was finalized on 15th April 2016, 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: Nick Athanas, Alfonso Auerbach, Peter Boesman, David Bradley, Robin Carter, Paul Driver, Francisco Dubon, Manuel Grosselet, Jon King, Doug Knapp, Mike Nelson, Andrew Spencer and John van Dort.
Sosa-López, J.R., Mennill, D.J. & Navarro-Sigüenza, A.G. (2013). Geographic variation and the evolution of song in Mesoamerican rufous-naped wrens Campylorhynchus rufinucha. J. Avian Biol. 43(1): 1–12.
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: on289_rufous-naped_wren.pdf