Zoo-housed female chimpanzee adopts local female-specific tradition upon immigrating into a new group

Zoë Goldsborough,Edwin J.C Van Leeuwen,Christine E Webb,Frans B.M De Waal

doi:10.1163/1568539x-bja10075

Abstract

Abstract Wild female chimpanzees typically migrate to a neighbouring community at the onset of sexual maturity, a process that can be dangerous and unpredictable. To mitigate the risk of rejection in the new community, immigrants may employ several behavioural strategies. During the integration of two chimpanzee females at Royal Burgers’ Zoo (Arnhem, The Netherlands) one of the immigrant females rapidly copied a local tradition — the crossed-arm walk — which has been present in the group for over 20 years. She copied the behaviour after meeting only one resident female, and showed the behaviour frequently throughout a 6-month observation period following the introduction. The other immigrant female never adopted the crossed-arm walk, highlighting the variation in behaviour by immigrants upon integration, as well as the potential associated consequences: in a separate observation period 2 years later, the female who copied the local tradition appeared more socially integrated than the other immigrant female.

Highlights

Chimpanzees are a patrilocal species in which the females migrate to neighbouring communities upon becoming sexually mature (Goodall, 1986; Nishida et al, 1999)
We describe how an immigrant female chimpanzee (Moni) copies an idiosyncratic group-specific behaviour soon after being introduced to a new group
Two days after first contact with a resident female, before meeting any other resident individuals, Moni engages in crossed-arm walking: an inefficient means of locomotion without clear function that is enacted by the majority of females in the new group

Summary

Introduction

Chimpanzees are a patrilocal species in which the females migrate to neighbouring communities upon becoming sexually mature (Goodall, 1986; Nishida et al, 1999). Instead of sampling the local contingencies with risky and time-consuming trial-and-error learning, an individual may attend to the behaviour of residents and adopt their choices (Hoppitt & Laland, 2013). This logic plausibly holds for tangible manipulations of the environment (e.g., what plants to eat, what material to use for extractive foraging or nest building), but what about social conventions of which the function is opaque or even non-existent apart from the fact that everybody’s doing it, like the finger-in-mouth games in capuchin monkeys or the grass-in-ear behaviour in chimpanzees (Perry et al, 2003; McGrew, 2004; van Leeuwen et al, 2014)?. In Period 1 we used hourly rates of grooming, in Period 2 dichotomous occurrence of grooming per session (see Appendix)

Methods

Results

Conclusion