In the following we briefly analyze and compare voice of the different races of Rusty Pitohui (Pitohui ferrugineus). 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), and we received additional recordings of race leucorhynchus from Phil Gregory.
Rusty Pitohui is a good songster, and has a variety of song phrases consisting of rich fairly low-pitched whistles, but also rising series of whistles, sometimes alternated with fast repetitions of a single note. There is thus considerable variation in its voice.
leucorhynchus from Waigeo is morphologically quite distinct, for which we check its voice here versus other races (illustrated by sonograms in the pdf version): a combination of rich whistles, sequences of repeated notes and a simple phrase of 2-4 rising notes repeated.
We have looked for song phrases of other races that mostly resemble the above (illustrated by sonograms in the pdf version): rich whistles, repeated notes and a simple phrase of 2-4 notes repeated
From the above it is clear that there is no obvious difference in basic sound parameters.
At the other hand, we have not found exact matches for several whistles (note shapes), but variation is at least as extensive among other races/indviduals as between leucorhynchus and all others. To prove that whistles of leucorhynchus are truly unique and typical for this taxon, we need to be sure that in a larger sample set of other races we don't find any of such whistles AND in a larger sample set of leucorhynchus we don't find a wider range of whistles causing overlap with other races. Note that at this point it is impossible to assign any new recording to either group unless a similar recording already exists, which is not at all likely given the extreme variation of whistled phrases.
We can thus conclude that some whistled notes of leucorhynchus are not well matched by other races, but variation in song is high in all taxa, so that far more samples are needed to prove any consistent differences.
This note was finalized on 23rd February 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 and ML: Nick Athanas, Phil Gregory, Andrew Mack, John V Moore, Bas Van Balen and Iain Woxvold.
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: on163_rusty_pitohui.pdf