Self-Medicative Behaviour in Chacma Baboons

Region: Wildcliff Nature Reserve, South Africa

Wildcliff Nature Reserve is approximately 955 hectares of deep kloofs (narrow valleys or gorges between mountains) with afro-montane forest, rocky mountaintops and high meadows of fynbos and renosterveld. The reserve is home to two troops of chacma baboons, one comprising less than ten members and the other with approximately 100. The larger troop is easier to follow and behavioural observations, faecal, plant and soil samples are being collected from these individuals.

Self-Medicative Behaviour
There is mounting evidence to suggest that primates obtain medicinal benefits from plant ingestion and this belief is gaining acceptance among primatologists. It has been hypothesised that secondary compounds present in plants and other non-nutritive sources have properties that help animals fight pathogens and parasites, improve the reproductive fitness of an individual, and lessen the many diseases caused by parasites.

The resident troop of chacma baboons at Wildcliff engage in geophagy – the practice of eating earth or soil-like substances, to obtain essential nutrients. Geophagy, one of the oldest known forms of self-medicative behaviour, has been observed in 20% of all primate species, but to date is essentially undocumented in baboons. It is apparent that geophagy is an important aspect of this troop’s repertoire, based on preliminary findings.

At a time when the human-baboon conflict is escalating it is imperative that we gain a better understanding of baboon needs. This study will determine the home and daily ranges, and the feeding ecology of a troop of chacma baboons (Papio ursinus) found on Wildcliff Nature Reserve in the Western Cape of South Africa.

Emphasis will be placed on self-medication in order to gain insight into how and what baboons need to maintain their health. This data has implications for the management of baboons, both captive and wild and for the field of primatology (study of primates in general).

Objectives

• Document baboon behaviour (spatial and feeding ecology).
• Monitor clay sites used by the baboons.
• Analyse clay.
• Collect faecal samples to be analysed for presence and abundance of parasites.
• Analyse all nutritive and non-nutritive items consumed by the resident troop.
• Determine underlying motivation for clay consumption.
• Based on secondary compounds present in diet, determine items in diet that may be used to maintain health homeostasis.

Observation of Behaviour
The resident troop of baboons is being followed from November 2009 through to August 2010. Behavioural observations – both individuals as well as the troop as a whole – will take place using a 15-minute scan method. Weather, location, and type (foraging, locomotion and social) will be documented.

Home and Daily Range Analysis
An adult female baboon will be trapped, sedated and collared with a self-releasing collar. Fixes will be captured hourly from 5am to 7pm. The battery should last for over one year.

Plant Consumption
Foraging behaviour is being documented – noting location, all nutritive and non-nutritive items consumed, and samples collected whenever possible. The aim is to find ingestion of items rare to the diet and/or of little nutritional value as well as ingestion of plants that are more common to the diet, but are also used ethno-medicinally by humans and/or have demonstrated biological activity, suggesting a medicinal component.

Faecal Analysis
Faecal samples of known individuals are collected whenever possible. Otherwise, anonymous samples are collected. The goal is to collect 20 samples every two weeks. All samples will be analysed in the parasitology laboratory at Kyoto University’s Primate Research Institute.

Soil Analysis
In order to gain insight as to why the baboons consume clay on and around Wildcliff Nature Reserve, soils will be analysed. Several representative samples have been taken from areas where soil consumption is known to occur. Additionally, samples of neighbouring soil not consumed will also be sampled.

This project has been completed and an in depth report has been published. This is an extract from the report:

“Despite baboons’ widespread distribution across Africa, geophagy among all species has been poorly documented. We used video camera traps and soil analysis to investigate geophagy in chacma baboons inhabiting the Western cape of South Africa. During an 18-month Study from August 2009 to January 2011, we continually monitored the largest and most frequently visited geophagy spots with camera traps for 545 days and captured soil consumption at one or more sites on 266 of those days (49%). In 3 500 baboon visits to the geophagy sites, video camera traps captured 58.6 hours of geophagy.

From these data, we evaluated site preference based on time spent consuming soil among these four geophagy sites. 170 days of soil consumption from the most visited geophagy site allowed us to look for demographic trends in geophagy.  Selected consumed soils from geophagy sites were analysed for mineral, chemical and physical properties. The baboons spent more time consuming white alkaline soils with high percentages of clay and fine silt, which contained higher concentrations of sodium than non-white acidic soils that contained higher concentrations of iron. Our data indicate that pregnant chacma baboons spend more time consuming soil at monitored geophagy sites than any other age class, sex or reproductive state. Based on analytical results, the soils consumed would be effective at alleviating gastrointestinal disturbances and possibly supplementing minerals for all age/sex classes.”

Click here for the full report.

Annual  Report 2011
This is the first study to document geophagy in the genus Papio since a brief account by Hall, 1965; these findings were presented at the International Primatological Society’s Congress in September 2010.
Fieldwork has been completed, as have statistical analyses on over 1 800 trap camera images at three clay sites on and around Wildcliff Nature Reserve. The results show that the baboons spend more time consuming soil that is alkaline rather than acidic and has high concentrations of clay and silt. Time spent consuming clay by age class, gender and reproductive state has also been determined and the data is being submitted for publication.

Parasite Analysis:
Parasites are ubiquitous in nature, and controlling their intensity and infestation is one of the greatest health challenges facing wild animals. 275 baboon faecal samples were analysed at Kyoto University’s Primate Research Institute (PRI) in Japan for prevalence, diversity and intensity. The Wildcliff troop is infected with several protozoans, at least 7 nematodes and at least one cestode. The focus of this study is nematodes. Because, hookworm eggs are morphologically indistinguishable, I am currently culturing the eggs so identification can be made at the larval stage, which is distinct. The cestode proglottids will be genetically analysed in February. I will be looking at diet, use of medicinal plants, and plants with secondary plant metabolites, such as tannins and alkaloids, and their affect on parasite intensities. I will also look for correlations in parasite intensity and climatic conditions. It is expected that parasite infection is highest during the rainy season and times when the baboons consume foods found in close association with soil, i.e. tubers, roots, corms, and bulbs. Additionally, I have begun a meta-data analysis to determine how many dietary items the baboons consume with known medicinal properties.

January to June 2010
This report covers the entire 18 months of my study, but I will focus on the first two quarters of the year,

January – June 2010.
Field Work:
To date I have followed the Wildcliff chacma baboon troop for 18 months and have taken approximately 5000 focal observations that document the foraging, locomotion and social behavior of the troop. Because my area of interest is self-medicative behaviour, I pay close attention to what specific nutritive and non-nutritive items the baboons consume.  I have observed the troop feeding on 61 different items.  Included in this list are several medicinal plants and plants containing strong secondary compounds.  Preliminary results, however, suggest clay is the dietary item most important to maintaining health homeostasis.  Consumption of clay, geophagy, is the oldest form of self-medicative behaviour known to humans.

Video Trap Cameras:
The troop exploits clay from four major sites on and around Wildcliff Nature Reserve.  Trap cameras have been set up to monitor the activity at three of these sites.  Funds received from the Wilderness Trust allowed me to purchase two additional trap cameras. I have been able to capture thousands of feeding bouts at these three clay sites.  I am currently focusing on one clay site and the images from one camera.  I am currently analysing data involving 2,295 observations of geophagy .  The images from this site are excellent and allow me to determine the age, sex, and reproductive status of the individuals feeding on the clay.

Clay Analyses:
With the help of the Wilderness Trust, clay from all clay sites has been analysed.  The types of analyses completed were X-ray fluorescence (XRF), X-ray diffractometry (XRD), atomic absorption spectrophotometry (AAS), pH, and particle size. The clays have been classified as kaolinite-illite. They are a good source of sodium but but are not rich in other minerals. Additionally, the pH of the clay consumed is high, in the range of 8-10.  I am still analysing my data, but this clay may regulate the pH of the GI tract while providing sodium, which may be lacking in the baboons’ diet.

Dietary analysis:
With my funding I have also had Acacia mearnsii (black wattle) seeds analysed, as they comprise greater than 30% of the baboons’ diet.  Laboratory results concluded that the seeds are composed of  8% fat, 22% protein, 43% dietary fibre, 17% carbohydrates and no sugar.  Further analyses being conducted at the Free State University will document presence or absence of tannins.  I have also had the seeds analysed at the University of Stellenbosch, Central Analytical Facility for micro and macronutrients.  The black wattle seeds are very low in sodium, calcium, magnesium, potassium and phosphorous.  They do appear to be a good source of copper, iron, zinc and manganese.  This kind of data will help me determine the underlying motivation for the clay consumption of this troop.

I will remain in the field until the end of August 2010.  In September I will be giving an oral presentation on how trap cameras can help monitor geophagic behaviour at the International Primatological Congress in Kyoto Japan.  The data presented at the congress will be written up and submitted for publication.