A Short-Term Visit of an Adult Male Bonobo from the Neighboring Unit-group at Wamba

Abstract

22 INTRODUCTION The social organization of male-philopatry is often explained by the importance of cooperation among kinrelated males to defend their group territories and the encompassed females against other neighboring groups (Williams et al. 2004; Furuichi 2006). Strong hostility between males of different groups may make male visit and immigration into neighboring groups extremely difficult. In chimpanzees (Pan troglodytes), there is a higher likelihood of intergroup killing when large male parties encounter smaller male parties or lone males of different groups (Wrangham 1999). In reality, visiting males (temporary immigrants, see Nishida et al. 1999) have been only observed twice in Bossou, Guinea (Sugiyama 1999) during the period of over 55 years observing wild chimpanzees at multiple study sites. It has been observed that male bonobos (Pan paniscus) have more tolerant relationships with out-group males than do male chimpanzees (Sakamaki et al. 2018). Therefore, the obstacles to visit or immigrate faced by bonobos might be less than those encountered by male chimpanzees. However, there has been only one report of male visits at Lomako (Hohmann 2001) and one report of male immigrations at Wamba, Democratic Republic of the Congo (Hashimoto et al. 2008). Here, we report an additional case of a temporary visit by an adult male bonobo from a neighboring group at Wamba. Moreover, the social condition and motivation of his visit are discussed referring to other cases of the Pan species in this report.