SOCIAL AND ECOLOGICAL INFLUENCES ON ACTIVITY BUDGETS OF VERVET MONKEYS, AND THEIR IMPLICATIONS FOR GROUP LIVING

Activity patterns were documented over a 20-month period in six groups of vervet monkeys (Cercopithecus aethiops) in Amboseli National Park, Kenya. Group size varied both among groups and within groups through time. The home ranges of two groups were located in Acacia xanthophloe a habitat whereas those of four adjacent groups were located in A. tor tilis habitat. Repeated measures analysis of variance, three-way analy sis of variance, and meta-analysis of group size effects were carried out on feeding, moving, resting, scanning, allo-grooming, and 'other' behavior. Time spent feeding varied seasonally, peaking during periods when A. tortilis seeds were eaten. However, time spent feeding did no t vary within or among groups, or between habitats, males and females, or dominants and subordinates. Males spend more time scanning and les s time allo-grooming than females, and high-ranking individuals of bot h sexes spent more time scanning than low-ranking individuals. Among f emales, subordinates spent more time moving, whereas among males, domi nants spent more time moving. Groups living in A. xanthophloea habitat spent more time moving and allo-grooming than groups in A. tortilis h abitat but this may have been confounded by the fact that these two gr oups were on average larger than the others. Significant differences i n activity budgets among groups demonstrate that activity patterns obs erved in one group are not always readily generalized to other groups even when they come from the same population. Group size analyses exam ined potential costs and benefits of group living. Increased intragrou p competition, measured by time spent moving and feeding, was only wea kly evident in larger groups. Individuals in larger groups allo-groome d more than individuals in smaller groups. Self-grooming also increase d in larger groups. Individuals in larger groups spent less time scann ing than individuals in smaller groups, but there was more scanning pe r group in larger groups than in smaller groups.