We studied two groups of food-enhanced long-tailed macaques (Macaca fascicularis) that derived a quarter and half of their respective diets from anthropogenic food resources through human provisioning and feeding at refuse sites. The macaques alternated between feeding on natural food in the forest and feeding on anthropogenic food in adjacent urban areas. We found that dietary compositions of the macaques were correlated to natural fruit availability and macaques fed on natural fruits when available; but activity, habitat use and ranging patterns were correlated more to food availability from refuse sites and provisioning. Higher feeding on anthropogenic food resources was not correlated to natural fruit resource scarcity. Natural fruits constituted a highly variable resource base over the year and anthropogenic food resources provided a potentially more stable, albeit more opportunistic resource base. These results showed that the main drivers for macaque exploitation of anthropogenic foods were unlikely to be either natural food resource scarcity or a high dependence on anthropogenic foods. Behaviors associated with macaque anthropogenic food resource exploitation amplifies opportunities for undesirable interactions between macaques and humans. Addressing the accessibility of anthropogenic food resources to macaques through management intervention should be a priority for mitigating human-macaque conflict issues in Singapore.