Foraging and feeding behaviour of chacma baboons in a woodland habitat.

Abstract

Savannah baboons (Papio cynocephalus) have been studied in numerous sites throughout Africa. They have been found to display a wide variety of foraging and feeding behaviours. The aim of this study was to describe and quantify these for a troop in a southern woodland habitat and to determine what factors influence these in order to understand the choices made by baboons. This was done within an optimal foraging framework. The study included the development of random walk and optimal foraging simulation models of day journeys and a comparison of feeding and foraging before and after the troop divided into two daughter troops. The troop lived in a complex mosaic of habitat types with a high tree density. The troop's foraging strategies were found to be consistent with being time minimizers. Distance from the centre of the home range and distance from the nearest sleeping site had the most significant effect on utilisation of the home range. The effect of food availability on habitat use could only be distinguished by the use of simulation models. Comparison of food encountered by the troop and that encountered in the simulations demonstrated that the troop did better than could be expected if the day journey routes were random. The troop's results approximated those of a stochastic short-term optimisation model. The troop's diet consisted of a higher proportion of fruit than previous studies. The troop distinguished between commonly utilised foods and those only occasionally used on the basis of protein/fibre ratio, however food preference between main foods was not correlated with protein/fibre ratio. Any combination of the main foods would fulfil their protein requirement. Evidence is given that, without protein being limmiting, the troop's selection amongst the main foods is based on carbohydrate content. After troop fission the daughter troops had shorter day journeys, spent less time walking, more time socialising resting. They also spent more time in food-rich habitats and were more selective in their diet. These results reinforce the important influence in group size and suggest that troop fission may be seen as a time-minimising strategy.