Notes on the vocalizations of Olive-green Camaroptera (Camaroptera chloronota)

In the following we briefly analyze and compare voice of the different races of Olive-green Camaroptera (Camaroptera chloronota). 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).

Song is a long series of identical notes, typically falling (or occasionally rising) in pitch at first, then at equal pitch for a long period. Examples (illustrated with multiple sonograms):​ chloronota, kelsalli and toroensis.

Eastern race toroensis seems to differ somewhat in voice, for which I have examined all available recordings:

                                          kelsalli (n=7)   chloronota (n=4)  toroensis (n=12)

frequency (latter part):    2500-3400Hz       2600-2890Hz      1500 - 3800Hz    

pace (1 period length):    0.25 - 0.29s          0.27 - 0.30s         0.18 - 1.02s

note length:                     0.09 - 0.13s          0.11 - 0.14s         0.09 - 0.40s

Song of toroensis is clearly much more variable. One could argue that this taxon has a fast and a slow song, but measurements for pace are: 0.18,0.23,0.24,0.27,0.34,0.50,0.60,0.66, 0.75,0.84,0.84 and 1.02 indicating there is no clear dividing line between two song types. Alternatively, we may discern a different slow song-type based on a typical note shape, but then other examples of slow song don't fit in here. All in all, it is safe to say that toroensis has clearly a much more varied vocabulary, leading to vocalizations with parameters such as pitch, pace, note length and note shape covering a much wider range (estimated score 2) (with the eternal remark that for the western races absence of recordings of such vocalizations does not necessarily mean they are actually absent).

This note was finalized on 10th 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: Sander Bot, James Bradley, Allen Chartier, Marcell Claassen, Sergey Dereliev, Phil Gregory, Gabriel Jamie, Linda Macaulay, Carolyn McBride, Dolly Minis, David Moyer, Mike Nelson, Bram Piot, Paul Rodewald, Martin St-Michel, Keith Stuart and Dale Zimmerman.

 

References

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: on224_olive-green_camaroptera.pdf