Vocal Diversity of Kloss’s Gibbons (Hylobates Klossii) in the Mentawai Islands, Indonesia

Gibbons (family Hylobatidae) are generally described as monogamous, frugivorous, arboreal, and territorial apes and inhabit tropical and subtropical forests of South and Southeast Asia (Marshall and Sugardjito 1986; Leighton 1987; Chivers 2001; Geissmann 2003). All gibbon species are known to produce elaborate, loud, long, and stereotyped patterns of vocalization often referred to as ‘‘songs’’ (Marshall and Marshall 1976; Haimoff 1984; Geissmann 1993, 1995, 2002b, 2003). Generally, song bouts are produced in the early morning and last approximately 10–30 min. Species-specific song characteristics in gibbons are thought to have a strong genetic component (Brockelman and Schilling 1984; Geissmann 1984; Tenaza 1985; Marshall and Sugardjito 1986; Mather 1992; Geissmann 1993). It has previously been demonstrated that gibbon song characteristics are useful for assessing systematic relationships on the level of the gibbon genus, species and local population, and for reconstructing gibbon phylogeny (Haimoff et al. 1982; Haimoff 1983; Creel and Preuschoft 1984; Haimoff et al. 1984; Marshall et al. 1984; Geissmann 1993, 2002a, b; Konrad and Geissmann 2006; Dallmann and Geissmann this volume)

Individual and Geographical Variability in the Songs of Wild Silvery Gibbons (Hylobates Moloch) on Java, Indonesia

The present study focuses on the great-call phrases of wild female silvery gibbons (Hylobates moloch). The aim of this study is to answer the following questions: (1) To what degree is great-call variability within a species useful for both individual and population identification? (2) Do vocal differences among local populations correspond to geographical distances or do they show evidence for genetic isolation among populations? (3) Can vocal data be used to test the validity of subspecific taxon boundaries suggested by previously reported genetic data