Dallmann, R. & Geissmann, T. 2001: Different levels of variability in the female song of wild silvery gibbons Hylobates moloch. In: The XVIIIth congress of the International Primatological Society: Primates in the new millennium. Abstracts and programme, Adelaide, South Australia, p. 127.

Different levels of variability in the female song of wild silvery gibbons Hylobates moloch

R. Dallmann and T. Geissmann
Institute of Zoology, Tieraerztliche Hochschule Hannover, Buenteweg 17, D-30559 Hannover, Germany

Gibbons produce long, loud and stereotyped song vocalisations which contain species-specific, sex-specific and probably individual characteristics. We introduce the mean pairwise difference (MPD) of scaled variables in order to quantify great call variability and individuality. The results are, in contrast to previously used methods, largely independent of sample size. We analyzed various levels of variability in female great calls of wild silvery gibbons in Java (Indonesia). Our results show that females can be distinguished by their great calls, variability is significantly lower within one population than among any two populations, and great calls can be distinguished by level-specific acoustical features.