The Proboscis Monkey (Nasalis larvatus), Social Group Structures

Abstract

The proboscis monkey (Nasalis larvatus) is a large old world monkey, indigenous to Borneo. In the coastal areas of this island, groups of proboscis monkeys live together without a lot of territorial aggression. Studies conducted on the social organization of this monkey do not unanimously agree on its group composition. Phylogenetically it differs a lot from the other Colobines and might therefore show more resemblance to the Papio genus. Comparing the proboscis monkey to other Colobines shows that snub-nosed monkeys have a similar social structure. The multilevel society and fission-fusion behaviour of these monkeys make it a good example for the possible social structures of the proboscis monkey. While the baboons also exhibit these behaviours, the levels of its multilevel society are more extensive than observed for the proboscis monkey. Because of this a lot of influences on the social organization are added. This draws the conclusion that snub-nosed monkeys have the most similar social organization to the proboscis monkey. The combined literature in this thesis gives an overview of the monkey’s social behaviour in the wild and mentions new insights on how to successfully keep them in an artificial environment. With the knowledge on maintaining groups of proboscis monkeys in captivity, zoos can cooperate and work against the extinction of this species in the wild.