Preliminary vocal repertoire and vocal communication of wild bonobos (Pan paniscus) at Lilungu (Democratic Republic of Congo).

Vocal communication in bonobos, Pan paniscus, has been studied mainly in captive groups. The few studies carried out in the wild are on only specific aspects of their behaviour. The aim of this study is to give a preliminary description of the vocal repertoire and a qualitative account of the contextual use of the vocalizations described. Observations were carried out on three wild communities, with a total of 68 individuals, for 685 h. No artificial feeding was used at any stage of the study. The vocal repertoire is composed of 15 vocal units and 19 sequences. There is great variability both in the sequences and in the vocal units, and the categories are not always completely discrete. The repertoire is compared to that of captive bonobos described by De Waal. Most sequences are used in various contexts, and for each behaviour there is a complete array of sequences and their variation. The behaviour patterns observed and the sequences uttered by the animals in each context are discussed.