Sex Bias and Social Influences on Savanna Chimpanzee (Pan troglodytes verus) Nest Building Behavior

Fiona A Stewart,Jill D Pruetz

doi:10.1007/s10764-020-00157-4

Abstract

Many primates show sex differences in behavior, particularly social behavior, but also tool use for extractive foraging. All great apes learn to build a supportive structure for sleep. Whether sex differences exist in building, as in extractive foraging, is unknown, and little is known about how building skills develop and vary between individuals in the wild. We therefore aimed to describe the nesting behavior of savanna chimpanzees (Pan troglodytes verus) in Fongoli, Senegal to provide comparative data and to investigate possible sex or age differences in nest building behaviors and nest characteristics. We followed chimpanzee groups to their night nesting sites to record group (55 nights) and individual level data (17 individuals) on nest building initiation and duration (57 nests) during the dry season between October 2007 and March 2008. We returned the following morning to record nest and tree characteristics (71 nests built by 25 individuals). Fongoli chimpanzees nested later than reported for other great apes, but no sex differences in initiating building emerged. Observations were limited but suggest adult females and immature males to nest higher, in larger trees than adult males, and adult females to take longer to build than either adult or immature males. Smaller females and immature males may avoid predation or access thinner, malleable branches, by nesting higher than adult males. These differences suggest that sex differences described for chimpanzee tool use may extend to nest building, with females investing more time and effort in constructing a safe, warm structure for sleep than males do.

Highlights

Many primates show sex differences in physical and social development, for example in social interactions such as grooming, play, and the development of complex foraging skills
Juvenile male primates tend to engage in more play, and rough-and-tumble play (Meredith 2015), than females and there is some evidence of greater object manipulation play in juvenile male chimpanzees (Pan troglodytes) than in females (Koops et al 2015)
On four occasions we lost the chimpanzees before beginning nest building and on two occasions FS left the group before nesting was finished because of the late time of night and distance from camp, as the chimpanzees had not finished or started nesting by 22:30 and 20:30 h respectively

Summary

Introduction

Many primates show sex differences in physical and social development, for example in social interactions such as grooming, play, and the development of complex foraging skills (reviewed in Lonsdorf 2017). Female primates show a bias toward play parenting or mothering behaviors (reviewed in Lonsdorf 2017) Such sex biases in behavior during development in primates are related to social organization and are subject to selection for the skills necessary for survival and reproduction in adulthood (Lonsdorf 2017). Sex differences in termite fishing skills begin early during development and suggest that males’ techniques and tools have less fidelity with the mothers’ than juvenile females’, because males invest more time in play and social activities from a young age (Lonsdorf et al 2004)

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