Behavioral Biology of Chacma Baboons in Tokai, Cape Peninsula, South Africa

Since 2006, I have been involved in research on the behavioral biology of chacma baboons in the Cape Peninsula of South Africa. This began as an informal collaboration with Drs. Becky Ackermann, Justin O'Riain, and others at the University of Cape Town, which led to the inception of the Cape Peninsula Baboon Research Unit, known locally as the Baboon Research Unit or BRU.  Research conducted as part of BRU encompasses various aspects of baboon biology, including ecology, behavior, genetics and physiology, as well as aspects of human-baboon relationships and the mitigation of baboon-human conflict.

There are currently fourteen troops of baboons on the Cape Peninsula, and they form an isolated population due to the sprawling suburbs of Cape Town, which effectively block dispersal by baboons to surrounding regions. Like many baboon populations across Africa, the baboon population in the Cape Peninsula is under increasing pressure from human habitation, with commensalism and conflict between humans and baboons becoming increasingly prevalent. Nearly every troop on the Peninsula has some contact with humans, whether it be raiding human-derived resources (gardens, garbage bins, food from cars), being chased and threatened by humans defending their property, or being herded by baboon monitors employed by the authorities to keep baboons out of residential areas and mitigate conflict. 

Part of the goal of BRU as a research group is to generate information about baboon behavior and ecology that will aid in conservation and management of this and other baboon populations. Current and recently completed research projects include:

  • the behavioral ecology of Cape Peninsula baboons and the effects of monitors on baboon behavior (Angela van Doorn)
  • the effects of injuries (mainly anthropogenic) on baboon behavior (Esme Beamish)
  • the impact of human behavior on baboon behavioral ecology (Angela van Doorn, Esme Beamish)
  • annual population census work on Cape Peninsula baboons (Esme Beamish)
  • ranging patterns and habitat use of Cape Peninsula baboons (Tali Hoffman)
  • marine foraging ecology of baboons in the Western Cape (Matthew Lewis)
  • nutritional ecology of baboons in the Tokai Forest (Caley Johnson, Brad Rebeiro, and David Clarke)
  • baboon deterrent strategies and mitigation of baboon-human conflict in the Cape Peninsula (Bentley Kaplan)
  • parasite prevalence across baboon troops in the Cape Peninsula and parasite transmission between baboons and humans (Damiana Ravasi)
  • behavioral indicators of stress in female baboons (Jacqui Stephenson)
  • causes and consequences of stress in female baboons and the adaptive value of social bonds (Shahrina Chowdhury)
  • population genetics of baboons of the Western Cape (Jacqueline Bishop)
  • female cycle state, consortships, and male raiding behavior (Marie Vergamini, Lucy Nepstad, and Grace Davis)
  • male dominance rank, aggression, and raiding behavior (Grace Davis)


Additional BRU research projects are described on the BRU website under Projects.   Most of the BRU projects so far have been supervised by Dr. Justin O'Riain or myself.  Currently, my team is focused on the most northerly troops, those in the Tokai section of the Table Mountain National Park in the southern suburbs of Cape Town.  Publications from this research may be viewed here.

Since 2009, my doctoral student Shahrina Chowdhury has been investigating social and environmental sources of stress in female baboons in Tokai, as well as social strategies to mitigate chronic stress. Female chacma baboons in the Cape Peninsula are exposed to not only the social stressors faced by all chacma baboon females but also to environmental stressors resulting from baboon-human conflict.  Via a comparison of three troops of baboons in Tokai that vary in demographic structure, ranging patterns, and human contact, Shahrina aims to determine the impact of these various stressors on circulating stress hormones and short-term measures of reproductive output, as well as the potential mitigating effects of social bonds that females form with other females and with males.

As a follow-up to Shahrina's work on the mitigating effects of social bonds on chronic stress, post-doctoral researcher Dr. Steffen Foerster and I are currently collaborating on a multi-faceted project focusing on proximate mechanisms of stress mitigation in female baboons in Tokai.  Conceived and led by Steffen, this project tests several proposed proximate pathways underlying the previously demonstrated relationship between sociality and fitness in female baboons (Silk et al., 2003, 2009), particularly whether elevated stress hormone levels increase the likelihood of developing intestinal parasite infections in female baboons and whether strong social bonds mitigate this risk.  More broadly, we are investigating the links between ecological variation, variation in social bonds, and physiology and reproduction in female baboons.  More details about this project may be found on Steffen's website.

Loosely linked to BRU is Imfene, a South Africa-based educational public outreach website developed by Julian Saunders and myself. Among the goals of Imfene is the dissemination of information about baboons and commensalism to the public in an effort to foster awareness of baboon ecology, the causes of commensalism, and what people living near baboons can do to mitigate commensalism and conflict. More broadly, Imfene aims to improve the relationship between baboons and humans in Africa and thereby contribute to baboon conservation and human conservation awareness.  Recently, Lucy Nepstad has joined Imfene and has begun giving lectures on baboon awareness to elementary school children in Cape Town.


all text and photos copyright © Larissa Swedell