The Role of Vigilance in the Survival and Reproductive Strategies of Desert Baboons

Abstract

This study investigates the relative importance of vigilance in the survival strategies (detection of predators) and reproductive strategies (detection of mates and competitors) of adult baboons Papio cynocephalus ursinus among four groups in a desert population. The proportion of time spent vigilant under a variety of conditions was quantified through instantaneous sampling of focal individuals. Matched comparisons were then conducted to test six predictions for each functional explanation (survival or reproduction). These relate vigilance to (1) sex, (2) group size, (3) activity, (4) habitat, (5) refuge use and (6) spacing behaviour. Vigilance levels do not differ between sexes or groups. However, females are more vigilant when engaged in high-risk activities, when distant from refuges and when distant from neighbours. Male vigilance similarly covaries with refuge use and spacing behaviour, but males are not always more vigilant in dangerous activities and show greater vigilance in open rather than closed habitats. According to the predictions tested, the results provide partial support for the proposal that vigilance plays a role in predator detection for both sexes, although in males the detection of potential mates and competitors appears to be of greater importance. There was no evidence that males provide a vigilance service for females. Vigilance patterns are complicated by activity constraints and the multifactorial nature of anti-predator strategies.