In the following we briefly analyze and compare voice of the three races of Lemon-rumped Leaf-warbler (Phylloscopus chloronotus). 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 are only a few recordings of chloronotus/simlaensis available (illustrated by multiple sonograms in the pdf version of this note): song and call (some possibly misidentified?).
To be compared with vocalizations of forresti: song and call.
Voice of both groups seems to be quite different, although full extent of vocabulary of chloronotus/simlaensis possibly not covered in above examples, as two song types have been described (Alström 2016). In any case, it would seem that there are consistent differences which allow any recording to be immediately assigned to either group, e.g. freq. range of notes in above song type much wider in forresti (score 2) and pace slower (at least for the ending rattle, score 2). Furthermore, call note of forresti is surprisingly uniform and quite different from anything recorded for chloronotus/simlaensis (allow score2).
All in all, when applying Tobias criteria, this would lead to a total vocal score of at least 4. While this score is based on rather few recordings, the findings formulated here are clearly confirmed by Alström (2016), increasing the level of confidence.
This note was finalized on 24th 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: Nick Athanas, Oscar Campbell, Dave Farrow, Frank Lambert, Yong Ding Li, Mike Nelson, Lakshminarasimha Ranganathan and Manuel Schweizer.
Alström, P. (2016). Lemon-rumped Leaf-warbler (Phylloscopus chloronotus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/58881 on 24 February 2016).
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.