Beyond the group: how food, mates, and group size influence intergroup encounters in wild bonobos

Abstract

In social-living animals, interactions between groups are frequently agonistic, but they can also be tolerant and even cooperative. Intergroup tolerance and cooperation are regarded as a crucial step in the formation of highly structured multilevel societies. Behavioral ecological theory suggests that intergroup tolerance and cooperation can emerge either when the costs of hostility outweigh the benefits of exclusive resource access or when both groups gain fitness benefits through their interactions. However, the factors promoting intergroup tolerance are still unclear due to the paucity of data on intergroup interactions in tolerant species. Here, we examine how social and ecological factors affect the onset and termination of intercommunity encounters in two neighboring communities of wild bonobos, a species exhibiting flexible patterns of intergroup interactions, at Kokolopori Bonobo Reserve, Democratic Republic of the Congo. We recorded the timing and location of intercommunity encounters and measured fruit abundance and distribution, groups’ social characteristics, and space-use dynamics over a 19-month period. We found that intercommunity tolerance was facilitated by a decrease in feeding competition, with high fruit abundance increasing the likelihood of communities to encounter, and high clumpiness of fruit patches increasing the probability to terminate encounters likely due to increased contest. In addition, the possibility for extra-community mating, as well as the potential benefits of more efficient foraging in less familiar areas, reduced the probability that the communities terminated encounters. By investigating the factors involved in shaping relationships across groups, this study contributes to our understanding of how animal sociality can extend beyond the group level.

Behavioural diversity of bonobo prey preference as a potential cultural trait

“…Accounting 45 for potential local ecological drivers is methodologically challenging in chimpanzees, a 46 territorial species where each group predominantly occupies unique non-overlapping areas 47 (Mitani et al, 2010;Samuni et al, 2017). In contrast, the tolerant intergroup relations of 48 bonobos (Furuichi, 2020;Lucchesi et al, 2020) permit a context in which different 49 behaviours are expressed by individuals of different groups in the same place and at the same 50 time. Here, we investigate variation in bonobo predation patterns of two groups (Ekalakala 51 and Kokoalongo) at the Kokolopori Bonobo Reserve.…”

Do people manage climate risk through long-distance relationships?

“…While bonobos and gorillas are also flexibly tolerant toward rarely-encountered individuals or strangers (Bermejo, 2004;Fruth & Hohmann, 2018;Lucchesi et al, 2020;Tan et al, 2017), the degree to which humans rely on relationships with rarely-encountered individuals is unique among the great apes (Pisor & Surbeck, 2019). Our flexible interest in long-distance relationships is likely an adaptation to our foraging ecology and our high energy throughput, suggesting that far-flung social connections have likely been a feature of human social networks since the origins of Homo (Pisor & Surbeck, 2019).…”

Better together? How intergroup associations affect energy balance and feeding behavior in wild bonobos

“…Generally, when resources are economically defensible and the benefits of exclusive resource access surpass the costs of resource defense, groups are expected to interact agonistically (Grant 1993;Maher and Lott 2000;Dubois and Giraldeau 2003). Conversely, when resources are not economically defensible due to their abundance or dispersion, or when the costs of sharing resources with neighbors are offset by the benefits conferred by these interactions, groups may show tolerance to out-group members (Dubois and Giraldeau 2003;Robinson and Barker 2017), to the extent that distinct social units may choose to participate in prolonged intergroup associations (plains zebras, Equus burchelli: Rubenstein and Hack 2004; African elephants, Loxodonta africana: Wittemyer et al 2005; sperm whales, Physeter macrocephalus: Whitehead et al 2012; bonobos, Pan paniscus: Sakamaki et al 2018;Lucchesi et al 2020).…”

“…As a species exhibiting intergroup tolerance with encounters frequently developing into long-lasting intergroup associations extending over several consecutive days (Idani 1990;Sakamaki et al 2018;Furuichi 2020;Lucchesi et al 2020), bonobos (P. paniscus) are an excellent model in which to investigate the relative benefits and costs of intergroup associations. Bonobos are hominoid primates that live in multimale, multi-female social groups referred to as communities, which regularly fission into smaller parties to adapt to temporal fluctuations in food availability (Mulavwa et al 2008;Surbeck et al 2015).…”