Intergroup Transfer of Females and Social Relationships Between Immigrants and Residents in Bonobo (Pan paniscus) Societies

Abstract

International audienceThis paper first reviews data collected from 1976 to 2013 regarding the life histories of members of the main E1 study group of bonobos (Pan paniscus) in Wamba. The E1 group exhibited strong tendencies toward female dispersal and male residence during the entire study period, thereby exemplifying the typical characteristics of a male-philopatric and female-dispersal society. This pattern did not change after the abandonment of artificial provisioning. We then present two new cases of immigrant females, focusing especially on social association patterns, dominance relationships, and affiliative interactions during the approximate 2.5 years from the time of their immigration to their first birth. These females began engaging in social grooming with resident females immediately after their arrival but rarely did so with adult males, suggesting that they regard social bonding with females as more important than that with males. They also emigrated at a young age and frequently engaged in social play. Indeed, social bonding established through frequent social play may be related to the development of socially symmetrical relationships, which are the basis for the egalitarian bonobo society. Intragroup competition for food and mates was unlikely explanations for the tendency toward female dispersal. However, male residence and the risk of father–daughter incest may encourage female transfer among bonobo

Inter‐group aggressive interaction patterns indicate male mate defense and female cooperation across bonobo groups at Wamba, Democratic Republic of the Congo

“…However, such aggression rarely targeted out‐group females. Unlike chimpanzees, resident female bonobos are usually tolerant and affiliative to newly immigrant females (Idani, ; Sakamaki et al, ). In addition, a sole out‐group female sometimes visited the PE group during this study (see Section 2), and no aggression from resident females toward such visiting females was observed (N. Tokuyama, personal observation).…”

“…Bonobos ( Pan paniscus ) are interesting animals for investigating inter‐group interactions because of their unique social relationships, both within and between groups. They live in male‐philopatric multi‐male/multi‐female groups with stable memberships, which may split into temporary “parties” (fission–fusion grouping patterns, Kano, ; Sakamaki et al, ). Unlike other species, in which individuals of the philopatric sex usually have stronger association, affiliative, and cooperative relationships than the dispersing sex, association and affiliative behaviors in bonobos are more frequently observed among females, except for mother–offspring pairs (Furuichi, ; Moscovice et al, ; Surbeck et al, ; White, ).…”

<NOTE>A Female Bonobo Sleeping on the Ground after Daytime Birth and its Implications

“…Otomi (Ot) was one of two females that immigrated into E1 from an adjacent group in 2008, at which time she was estimated to be 11 years old (Sakamaki et al 2015). Ot successfully gave birth to her first offspring in January 2011, and it was named Otoko (Ok; ♀).…”

3. Equal, Similar, but Different: Convergent Bonobos and Conserved Chimpanzees

“…Bonobos do not show the pattern of lethal aggression observed in chimpanzees and even have been seen to socially interact and travel with neighboring groups (Furuichi et al, 2012). Female immigrants are prized social partners for resident female bonobos and they receive intense attention but relatively little physical aggression (Sakamaki et al, 2015;Ryu et al, 2015;Moscovice et al, 2015). These stark differences in social behaviors related to aggression and affiliation again illustrate what is at stake in more precisely estimating which species is more representative of Pancestor.…”