Gregariousness, foraging effort, and affiliative interactions in lactating bonobos and chimpanzees
Sean M Lee1, Gottfried Hohmann2, Elizabeth V Lonsdorf3
1Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, Washington, DC, USA.
Summary
Lactating chimpanzees, despite facing higher feeding competition, maintain social bonds similarly to bonobos by adjusting gregariousness without increasing foraging effort. This study reveals flexible social strategies in primates.
Area of Science:
- Primate behavior and socioecology
- Comparative ethology
- Evolutionary anthropology
Background:
- Fission-fusion dynamics are common in animals, primarily to reduce feeding competition.
- The costs associated with fission-fusion social systems, particularly for lactating females, are less understood.
- Bonobos and chimpanzees exhibit fission-fusion, but chimpanzees face greater feeding competition.
Purpose of the Study:
- To compare the costs of fission-fusion dynamics in lactating bonobos and chimpanzees.
- To evaluate differences in gregariousness, foraging, and social budgets between the two species.
- To understand how females mitigate feeding competition costs within their social structure.
Main Methods:
- Long-term observational data from wild bonobos (LuiKotale) and chimpanzees (Gombe) were analyzed.
- Gregariousness, foraging time, travel time, and social interaction time were quantified for lactating females.
- Comparative analysis of behavioral budgets between bonobos and chimpanzees was performed.
Main Results:
- Lactating chimpanzees were less gregarious than lactating bonobos, consistent with higher feeding competition.
- Foraging and travel times did not differ significantly between lactating bonobos and chimpanzees.
- Social interaction time was similar, with chimpanzees spending more time interacting with non-offspring individuals.
Conclusions:
- Lactating chimpanzees successfully maintain social budgets comparable to bonobos despite reduced gregariousness.
- Reduced gregariousness in chimpanzees does not necessitate increased foraging effort or reduced social interaction.
- The study highlights flexible social strategies in primates to balance feeding competition and social needs.
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