Food site residence time and female competitive relationships in wild gray-cheeked mangabeys (Lophocebus albigena)

Abstract

Authors of socioecological models propose that food distribution affects female social relationships in that clumped food resources, such as fruit, result in strong dominance hierarchies and favor coalition formation with female relatives. A number of Old World monkey species have been used to test predictions of the socioecological models. However, arboreal forest-living Old World monkeys have been understudied in this regard, and it is legitimate to ask whether predominantly arboreal primates living in tropical forests exhibit similar or different patterns of behavior. Therefore, the goal of our study was to investigate female dominance relationships in relation to food in gray-cheeked mangabeys (Lophocebus albigena). Since gray-cheeked mangabeys are largely frugivorous, we predicted that females would have linear dominance hierarchies and form coalitions. In addition, recent studies suggest that long food site residence time is another important factor in eliciting competitive interactions. Therefore, we also predicted that when foods had long site residence times, higher-ranking females would be able to spend longer at the resource than lower-ranking females. Analyses showed that coalitions were rare relative to some other Old World primate species, but females had linear dominance hierarchies. We found that, contrary to expectation, fruit was not associated with more agonism and did not involve long site residence times. However, bark, a food with a long site residence time and potentially high resource value, was associated with more agonism, and higher-ranking females were able to spend more time feeding on it than lower-ranking females. These results suggest that higher-ranking females may benefit from higher food and energy intake rates when food site residence times are long. These findings also add to accumulating evidence that food site residence time is a behavioral contributor to female dominance hierarchies in group-living species.

Fig. 1

The most likely dominance matrices for each group based on Bayesian analyses, accompanied by the posterior probabilities (pp) of the most likely rank orderings within the 95% credibility set. For example, the probability of the most likely rank ordering for LC is 42%, followed by the second most likely rank ordering, 28%, and the next 9%

Fig. 2

The relationship between the mean food site residence time and the percentage of contested food sites per food item

Fig. 3

Female rank by median bark food site residence time (N = 325). The highest-ranking female is assigned a rank of 1 and the lowest-ranking female, 7. Squares represent the medians, and bars and whiskers represent the 25% and 75% quartiles

Fig. 4

Agonistic rates for different populations of female Old World monkeys based on either total focal or total observation hours. See text for caveats related to the interpretation of these comparative data. Sources: (Cercopithecus aethiops and Erythrocebus patas, Isbell and Pruetz ; Cercopithecus mitis erythrarchus, Payne et al. ; Cercopithecus mitis stuhlmanni, Cords 2000, ; Lophocebus albigena, this study; M. fuscata, Saito ; M. fuscata yakui, Hill and Okayasu ; P. cynocephalus ursinus, Barrett et al. 1999)