Behavior, diet, and movements of the Sulawesi crested black macaque (Macaca nigra)

Abstract

We present the first field study of activity budgets, diet and ranging patterns of the Sulawesi crested black macaque, Macaca nigra, one of seven macaque species endemic to Sulawesi, Indonesia. We studied three crested macaque groups, ranging in size from 50 to 97 individuals, for 18 months in the Tangkoko-DuaSudara Nature Reserve, North Sulawesi. They spent 59% of the day moving and procuring food, especially fruits, and 41% of the day resting and socializing. Their diet is composed of more than 145 species of fruit (66% of observed feeding bouts), vegetative material (2.5%), invertebrates (31.5%), and occasional vertebrate prey. Group differences were more pronounced than seasonal or diurnal differences. Specifically, the largest group moved farther during the day, moved at a faster and more uniform rate, ate less fruit, rested more, and socialized less than the smaller groups did. The largest group had the largest home range, but it included less primary forest and more disturbed habitat than the ranges of smaller groups. There are individual differences in activity budgets of adult males and females in time spent moving, resting, feeding, and socializing that may reflect differences in reproductive strategies of males versus females. The behavior of large juveniles is more similar to that of adults than to that of small juveniles. Daily movements and use of home range are correlated with diet. Macaques moved shorter distances as the proportion of time spent feeding on fruit increased, and the top four dietary items accounted for most of the variance in entry into hectare blocks of home range.