Seasonal variation in the feeding ecology of the grey-cheeked mangabey (Lophocebus albigena) in Cameroon

Seasonal fluctuations in resource abundance often cause primates to change their feeding behavior and ecology. The objective of this study was to exam ine the response of a largely frugivorous monkey, the grey-checked mangabey (Lophocebus albigena), to seasonal variations in fruit abundance. We used 15-min scan sampling to quantify feeding, activity, and habitat use by monk eys between February and December 1998 in the Dja Reserve, Cameroon. L. alb igena were found to have omnivorous feeding habits, consuming the fruits, s eeds, leaves, and flowers of 132 plant species. Although monkeys fed from m any plant species, only five plant species accounted for 45% of all feeding records. The number of feeding observations on a plant species was signifi cantly correlated with its fruit production. L. albigena responded to fruit -lean periods by shifting from a diet dominated by fruit to one dominated b y seeds, flowers, and young leaves, This diet shift coincided with greater use of swamp habitat and higher dietary diversity. L. albigena spent the gr eatest percentage of scan samples feeding and traveling, but activities var ied significantly over the day. Individuals spent a significantly higher pe rcentage of scan samples feeding during the fruit-rich season than in the f ruit-lean season. Comparing our results to those of studies in Gabon and Ug anda, we found that L. albigena differ across regions in the number of plan t species they consume and time spent feeding. These differences may be a r esult of variations in tree diversity or the strength of seasonal fluctuati ons in resource abundance among sites. Am. J. Primatol. 54:91-105, 2001. (C ) 2001 Wiley-Liss, Inc.