Life in a fragment: Evolution of foraging strategies of translocated collared brown lemurs, Eulemur collaris, over an 18-year period.

While the drivers of primate persistence in forest fragments have been often considered at the population level, the strategies to persist in these habitats have been little investigated at the individual or group level. Considering the rapid variation of fragment characteristics over time, longitudinal data on primates living in fragmented habitats are necessary to understand the key elements for their persistence. Since translocated animals have to cope with unfamiliar areas and face unknown fluctuations in food abundance, they offer the opportunity to study the factors contributing to successful migration between fragments. Here, we illustrated the evolution of the foraging strategies of translocated collared brown lemurs (Eulemur collaris) over an 18-year period in the Mandena Conservation Zone, south-east Madagascar. Our aim was to explore the ability of these frugivorous lemurs to adjust to recently colonized fragmented forests. Although the lemurs remained mainly frugivorous throughout the study period, over the years we identified a reduction in the consumption of leaves and exotic/pioneer plant species. These adjustments were expected in frugivorous primates living in a degraded area, but we hypothesize that they may also reflect the initial need to cope with an unfamiliar environment after the translocation. Since fragmentation is often associated with the loss of large trees and native vegetation, we suggest that the availability of exotic and/or pioneer plant species can provide an easy-to-access, nonseasonal food resource and be a key factor for persistence during the initial stage of the recolonization.

Brown capuchin monkeys (Sapajus apella) plan their movements on a grasping task.

Motor planning is a relatively complex cognitive skill in which an actor modifies a behavior to anticipate the future consequences of the action. Studying motor planning in nonhuman primates may provide a better understanding of the roots of human planning abilities. In this study we presented capuchin monkeys (Sapajus apella) with a horizontal dowel baited on either the left or right end. A radial grasp on the dowel with the thumb facing toward the baited end would be the most efficient grip selection when bringing the dowel to one's mouth and indicate motor planning. Ten of the 12 monkeys tested spontaneously used a radial grasp significantly more often than expected by chance. Results demonstrate a more ubiquitous expression of motor planning abilities than previously seen in capuchin monkeys. Adaptation of this method of testing may be useful in evaluating motor planning capacity in other primates.