The influence of age, size and sex on feeding in yellow baboons: sexual segregation but not as we know it

Abstract

Yellow baboons are sexually size dimorphic mammals living in permanent stable mixed-sex troops: Puzzling in the context of our current theory on group living, sexual dimorphism and sexual segregation! This study is the first to investigate how male and female baboons live together despite body size differences. It hypothesizes they use subtle differences in diet and behaviour predicting that Subadult males will be more similar to adult females than larger bodied adult males. Testing this required looking at the behaviour of baboons in new ways by building on long-term research in an area high in abundance and diversity of baboon food species and habitats in Mikumi National Park (Tanzania) Data on dietary profile, space use and activity budgets from three-age-sex classes were collected using focal follows with instantaneous and one-zero recording: 70 individuals in 2 troops, over 270 days across 2 years. Findings demonstrate that baboon diets are diverse not just in terms of species. A range of plant parts and types (including sap and forbs) were eaten plus vertebrates and, especially, invertebrates. Food was packaged in a variety of ways with different processing requirements. Exotic food from a highway was also eaten although only made a very minor contribution to overall diet. Subadult males were more similar to adult females than adult males in their dietary profile (particularly in terms of parts and packages) and activity budgets (particularly in terms of relative allocation of time and number of activities but not synchrony). There were differences between age-sex classes in space use but no consistent patterns emerged. These findings suggest that adult male and female baboons are able to live together and avoid “classic” sexual segregation despite large difference in body size by subtle differences in what they eat but not in where and how they allocate their time for feeding