How bonobo communities deal with tannin rich fruits: Re-ingestion and other feeding processes

This report describes bonobo (Pan paniscus, Hominidae) behavioral flexibility and inter-community differences with high tannin level fruit processing. In fruiting plants, tannin should discourage certain seed dispersers (direct deterrence hypothesis) such as primates. Based on data deriving from five study sites; LuiKotale, Lomako, Wamba, Malebo and Manzano, we compare consumption and dispersal of fruit species rich in tannins: Parinari and Musanga pulp was chewed across all communities probably for saliva tannin neutralisation. However, consumption of the fruits of Canarium schweinfurthii was observed in few communities only with differences in the food process: While bonobos of Wamba, Lomako and Manzano crunched and swallowed the pulp, bonobos of LuiKotale ingested entire fruits, extracted intact fruits from feces, and re-ingested their pulp, spitting the seed after a retention time of 24 h in the digestive tract (i.e. endozoochory). We discuss potential functions of this peculiar feeding technique, likely to be a cultural behavior.