Time management in great apes: Implications for gorilla biogeography

Question: Do individual time budgets constrain a species' biogeographical distribution and group size? Data studied: We used published data on gorilla behaviour and ecology as well as published climate variables to model their spatial distribution across Africa. Method: We develop a mathematical model, based on the assumption that time is a fundamental ecological constraint. This novel approach uses the relationships between climatic variables and gorilla ecology and behaviour to calculate maximum ecological tolerable group sizes (and, from these, biogeographical distribution) for gorillas throughout Africa. Results: We show that the most critical variable limiting the distribution of gorillas is resting time, which in turn is related to the composition of their diet. Thus, the model demonstrates that time constraints on individual behaviour can explain species' biogegraphical distributions as well as group sizes.