Chacma baboon movement and behaviour in commercial timber plantations in South Africa and their association with bark-stripping

Pretorius, Michelle

Chacma baboon movement and behaviour in commercial timber plantations in South Africa and their association with bark-stripping

Thesis / Dissertation

2025

Publisher

University of Cape Town

Department

Department of Biological Sciences

Faculty

Faculty of Science

Abstract

As human populations expand, natural habitats have been heavily transformed primarily for agricultural land use, disrupting ecosystems and reducing the abundance and diversity of native fauna. Commercial forestry plantations, often described as ‘green or ecological deserts', are an example of an agricultural activity that has adversely impacted biodiversity. However, compared to commercial food crops, plantations offer relatively stable environments with longer rotations, and thus, may serve as a refuge for many wildlife species. In this thesis, I explore how native wildlife has responded to the widespread establishment of commercial tree plantations in the escarpment region of Mpumalanga Province, South Africa, and test the hypothesis that plantations are ‘green deserts' with reduced biodiversity. Camera trap surveys revealed that many wildlife species persist even under heavily transformed commercial plantations, with natural corridors within the plantation matrix being important for species persistence and dispersal. I then explored how chacma baboons (Papio ursinus), which appear to thrive in and around plantations, utilise this modified landscape. Plantations have been described as marginal habitat for baboons, and hence, were predicted to show a preference for patches of natural habitat interspersed within plantations. Using GPS data collected from 17 free-ranging baboon troops over a three-year period, I showed that baboons prefer plantations to other land uses, including natural (riverine, grassland), particularly during the wet season. Factors such as tree age, compartment size, tree species and productivity emerged as significant influencers of baboon movement and habitat use within plantations. These insights challenge previously held assumptions about baboon avoidance of pine compartments, and reveal that plantations may well serve as a critical refuge for baboons and other wildlife, as natural land is converted for commercial crops and urban developments throughout the region. However, this conservation potential of plantations is challenged by baboons that engage in bark-stripping, which damages the quality and hence the value of the trees. Despite the economic importance of bark-stripping to the industry, little information is available on factors that influence baboon bark-stripping behaviour. This information gap is, in part, due to the difficulty in observing a heavily persecuted species that can easily evade human followers in rugged terrain. To circumvent this challenge, I deployed “smart collars” equipped with tri-axial acceleration and GPS devices on multiple individuals within a single baboon troop. Acceleration data were successfully used to identify and quantify bark-stripping behaviour with high precision (98.3%) and recall (95.9%). Plantation baboons allocated up to 9% of their daily activity to bark-stripping, far exceeding previous estimates, and spent less time foraging and more time resting compared to baboons in natural habitats. Bark-stripping increased with higher ambient temperatures and various plantation-level variables, such as compartment productivity, compartment size, slope and distance to local human settlements. Bark-stripping was performed by all collared individuals which, given the high occupancy of baboons in plantations, explains the extensive damage recorded by plantation managers throughout Mpumalanga. While these findings do not provide a solution to such damage, they represent a crucial first step in addressing and mitigating this conservation conflict by providing an understanding of how baboons use plantations and the drivers of baboon bark-stripping.

Keywords

Forest Ecology and Management

Reference:

Collections

PhD / Doctoral

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