Baboons of the Pre-Namib – Life on the edge

By Guy Cowlishaw and Elise Huchard, Tsaobis Baboon Project

As the sun rises over the desert and the cold rocks begin to warm after a chilly winter’s night, a troop of sleepy baboons begins to stir on the koppie.

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With soft mutterings the mothers groom their infants, while the males climb higher to sit in the sun’s early rays. Holding their hands between their legs for warmth, they gaze out over the plains while the dawn wind ruffles their hair. Time passes, the baboons doze and groom one another, and the youngsters start to cartwheel and play tag over the boulders.

So begins another day in the life of a Tsaobis baboon troop. And another day in the life of a baboon troop observer. It’s an early start for us too. We must leave the comfort of our sleeping bags, eat our breakfast quickly, gather together our equipment and supplies for the day, and walk out to join the baboons before sunrise. Although baboons often linger for an hour or two before leaving the cliff where they sleep, occasionally they leave at first light, and if we’re not there to accompany them, it can take us days to find them again.

The right site

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The Tsaobis Baboon Project is an international research undertaking based at Tsaobis Leopard Park on the Swakop River south of Karibib. This is an important site in Namibia. It is where the ‘Pre-Namib escarpment region’ (which is rich in biodiversity, holding the majority of the country’s endemic species) and the Swakop River (which boasts Namibia’s largest and most densely populated ephemeral river catchment area, home to 200 000 people) coincide. Tsaobis itself is a beautiful and diverse environment. At its centre is the Potberg mountain, and in its majestic shadow there are rolling foothills and sweeping gravel and alluvial plains. The course of the Swakop River runs westward through this landscape, a conspicuous line of rich green woodlands dotting its banks.

In this unique place we have studied the desert baboons and their environment, in affiliation with the Gobabeb Research and Training Centre, since 1990. The Tsaobis Baboon Project is an international programme, with a UK base at the Institute of Zoology, the research arm of the Zoological Society of London. We are involved in a wide range of activities, including a monitoring scheme for the health of the Swakop River woodlands. However, our main focus is the behaviour and ecology of the desert baboons.

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‘Habituating’ the baboons

Studying baboons is not an easy job, although it is fantastically rewarding. To study baboons it is necessary to be able to observe them at close hand and to follow them on foot. This must be achieved without disturbing them, so that our presence does not alter their natural patterns of behaviour. The first step in any baboon study is therefore to ‘habituate’ the baboons. Through this process, which involves the observer following the troop day after day, week after week, the baboons become accustomed to the observer’s presence and begin to ignore the strange human being who is following them doggedly. It is tiring work and often frustrating, but eventually, after many months of persistent habituation, we become ‘accepted’ by the baboons. It is at this point that we can begin our research.

Over the years we have studied a range of different aspects of the lives of baboons. One of our first projects was to investigate how baboons respond to predation by leopards. Leopards only occasionally attack baboons, a pattern that partially reflects the ferocity with which baboons defend themselves if given half a chance. There have been several reports of baboons mobbing and killing leopards! However, we have found that baboons are still very sensitive to the threat of leopard attacks. Leopards are expert in ambush, and can attack and kill baboons before any defence can be mounted, so it makes sense for baboons to minimise this risk. Hence, from our studies, we have found that baboons will preferentially feed in open habitats where they can see an approaching predator more easily. Similarly, when possible, baboons stay close to refuges (such as tall trees and cliff faces) to allow a quick getaway should they be attacked.

Ongoing studies

Our two current studies focus on very different aspects of behaviour. The first project investigates how baboons choose their mates (see box below). The second project examines how baboon groups co-ordinate themselves. Do all members of the troop participate equally in group decisions, or is there a leader who makes decisions for everyone else? In other words, are baboon troops democratic or despotic? While these studies are ongoing, we hope that our first results will be ready later this year.

Perhaps the most important aspect of our study is the long-term nature of our project. Because we have been working at Tsaobis for so many years, we have been able to obtain insights that would not have been possible from shorter studies. We have been able to document important changes to the local environment, particularly along the ephemeral course of the Swakop River and its riparian woodlands. We have also been able to learn a great deal about the lives of the Tsaobis baboons. We have watched infants grow to adulthood, the rise and fall of dominant males, and tracked the careers and fates of the different families in the troops, their feuds and friendships. As time passes, our understanding of Namibia’s wildlife and environment continues to deepen. This knowledge. in turn. promotes a greater appreciation of Namibia’s unique and precious natural resources, and improves our ability to use wisely and conserve these resources for future generations.

What a baboon looks for when choosing its mate

Baboon mothers carrying a pink infant on their bellies, or jockey-style on their backs, is a typical but touching picture in Namibia. Baboons, like all primates, are long-lived animals. Young females begin to reproduce only around six years of age, each infant is suckled for more than a year, and only a limited number of offspring are born in a lifetime (about 20 to 25 years in total). It’s therefore crucial for mothers to ensure the best possible chances of survival for their progeny.

One way females can do this is by choosing their mates carefully. When females are at their most fertile, they normally mate with the dominant male. Such males can protect the infants when they are born, and hence make good fathers. However, females might also benefit from mating with males who possess certain genes. This is where our study comes in.

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There is one set of genes, called the Major Histocompatibility Complex (or MHC), that plays a central role in the immune system. These genes help determine the immune response that combats pathogens and parasites. MHC genes are exceptionally numerous and variable (as they need to be, given the diversity of infections that the body must be defended against), and as a result each individual carries a unique combination. From a female baboon’s point of view, it makes sense to choose a male whose MHC genes are different from her own. By doing so, her offspring will inherit the widest range of MHC genes possible and so have the best possible immune system, able to recognise and fight a wide variety of infections. This is true not just for baboons, but for other mammals as well. There is evidence that MHC genes are involved in mate choice in mice and even humans!

The focus of our study on baboon mate choice is therefore the importance of MHC genes. Are baboons with more diverse MHC genes healthier than others? And do baboons prefer mating partners with different MHC genes to their own? Watch this space…

This article appeared in the 2007/8 edition of Conservation and the Environment in Namibia.