ABOVE: In virgin primary forest troops of Pig-Tailed Macaques Macaca nemestrina are normally scarce nomads with very large ranges. Pig-tailed Macaques feed on fruit, large insects and small mammals. Most trees in Borneo fruit either annually or at intervals of several years known as mast fruiting. However where oil palm estates grow next to forest as at Tabin the Macaques stop wandering and become resident in the forest next to the oil palm which fruits continuously.
Pig-Tailed Macaques feed both on oil palm fruit and on the rats that are also attracted to oil palm estates. See this link to a study in West Malaysia: http://www.macaca-nemestrina.org/index.php/research/projects