Social foraging behaviour in a varying environment

Social foraging behaviour has an important influence on individuals’ survival and reproduction through its role in the acquisition of food resources. It also determines the amount of foraging time required in differing environments, and so the amount of time available for other activities, such as socialising and resting, which have been implicated in an individual’s fitness, as well as the stability of the wider social group. In this thesis I explore the links between these two processes by investigating the drivers of social foraging behaviour, and how the foraging time budgets that this behaviour produces vary between environments. I do this using data collected from a wild population of chacma baboons (Papio ursinus) in Namibia, under both natural and field-experimental conditions, and through the development of an individual-based model (IBM). I show that baboon foraging decisions are influenced by social and non-social factors, but that the relative influence of these factors is dependent on the characteristics of the forager and the habitat it is in. These differences in decision-making appear to allow all individuals in a group to experience similar foraging success under natural conditions, but this pattern breaks down in extreme conditions. Using these findings to build an IBM of social foraging, I show that the time individuals need to spend foraging can increase rapidly in a deteriorating environment to the point where they are no longer able to gather enough resources. Overall, the findings of this thesis contribute to the growing appreciation that social foragers can exhibit a high degree of behavioural flexibility. These findings also emphasise the long-standing recognition that individual-level behaviours have an important influence on higher-level ecological patterns and processes and that an appreciation of this is important, not only for our understanding of these patterns and processes, but also for informing conservation and management