The optimal foraging strategy used by Campbell’s Monkeys, Cercopithecus campbelli, in the dry season in the Taï National Park (Côte d’Ivoire)

Abstract

This study aimed to highlight the options selected by Campbell’s monkey (Cercopithecus
campbelli) to optimize foraging in the Taï National Park, Côte d’Ivoire. A group of C. campbelli,
habituated to human’s presence, was followed for two months in the dry season to test
whether the three parameters (the distance traveled to reach the foraging sites, the time spent
on these sites and the abundance of food resources on the sites) of Charnov’s marginal value
theorem (MVT) were correlated with each other. Group scan sampling and ad libitum sampling
techniques were used to collect data on the activities of individuals and the departure times
form foraging sites, respectively. The study showed that although mainly frugivorous,
Campbell’s monkeys increased significantly the consumption of a broad spectrum of
invertebrates during the long dry season. Moreover, no correlation was observed between the
three parameters taken two by two. The polyspecific association of C. campbelli with other
primate species in particular C. diana and C. petaurista, seems to have very little impact on
their optimization choices analyzed in light of Charnov's MVT. During the study period, usual
food resources were scarce, and monkeys shifted their diet towards invertebrates, which
maybe viewed as an optimization option during food scarcity periods.