Activity Patterns, Diet and Home Range of Night Monkeys (Aotus griseimembra and Aotus lemurinus) in Tropical Lowland and Mountain Forests of Central Colombia

Abstract

Most primates live in lowland ecosystems; however, some species have been particularly successful at colonizing higher altitudes, such as night monkeys (genus Aotus). Studies of the ecology of night monkeys in tropical forests are numerous, but behavioral data are limited due to the challenges associated with their nocturnal habits. Although Andean night monkeys (A. lemurinus) live in mountain forests >1000 m.a.s.l. and Caribbean night monkeys (A. griseimembra) live in rainforests <1000 m.a.s.l., they are found at similar tropical latitudes. Between 2018 and 2019, we followed three groups of A. lemurinus and one group of A. griseimembra at three sites in Colombia and recorded data on their ecology and behavior. Although they live at different altitudes, the two species had similar activity patterns and diet, investing approximately half of the night in resting (48%), and feeding primarily on fruits. We found differences among groups in the time invested in feeding on flowers, their home range, and distance traveled per night. These differences may be related to the unique characteristics of each study site and differences in resource availability and floristic composition of forests at different altitudes. Although the most important families in their diet were Moraceae and Urticaceae, highland groups also fed frequently on a large number of Melastomataceae and Rubiaceae trees. This research suggests these two nocturnal primates, living in contrasting environments, use similar strategies to cope with the challenges of being active at night in tropical forests.