In the following we briefly analyze and compare voice of the two races of Mascarene White-eye (Zosterops borbonicus). 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).
An overview of vocalizations per race, based on available recordings (illustrated with multiple sonograms in the pdf version of this note):
* a long series of variable high-pitched squeaky notes
* a somewhat more warbled short phrase at slightly lower pitch
* a sequence of downslurred chirping notes
There is a clear difference in voice. It is not 100% clear which are homologous vocalizations and which of the vocalizations can be considered territorial song, but in any case, none of the vocalizations of Mauritius are as squeaky and high-pitched as the ones commonly uttered on Reunion (score 3). The short more warbled phrases show more resemblance, and differences here are definitely more subtle. In absence of a clear set of homologous vocalizations, we estimate the total vocal score to be about 3.
This note was finalized on 16th March 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: Daniel Danckwerts, Phil Gregory, Frank Lambert, Dan Lane, Albert Lastukhin, Hans Matheve, Cedric Mroczko and George Sangster.
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: on262_mascarene_white-eye.pdf