Time: a hidden constraint on the behavioural ecology of baboons

Data from wild populations of baboons are used to derive functional equations relating time budget components, day journey length and group size to environmental variables. This set of equations predicts both time budgets in an independent sample of populations and the geographical distribution of baboon populations extremely well. I then use these equations to examine the maximum ecologically tolerable group size for baboons occupying different habitats. Groups which exceed this value exhibit signs of ecological stress: they spend less time resting and in social activity than would be expected for their size and environment, they are more likely to fragment during foraging and they travel faster. Populations living in poor quality (low rainfall) habitats are more likely to live in groups that are stressed in this way. © 1992 Springer-Verlag.