Maintaining social cohesion is a more important determinant of patch residence time than maximizing food intake rate in a group-living primate, Japanese macaque (Macaca fuscata).

Animals have been assumed to employ an optimal foraging strategy (e.g., rate-maximizing strategy).

A more detailed seasonal division of the energy balance and the protein balance of Japanese macaques (Macaca fuscata) on Kinkazan Island, northern Japan.

Nakagawa (Am J Primatol 41:267-288, 1997) reported that both the gross energy and gross protein intakes of an adult female Japanese macaque (Macaca fuscata) on Kinkazan Island, northern Japan, were high in spring (March-May) and fall (September-November) and low in summer (June-August) and winter (December-February), and that these values reflected the seasonal differences in nutritional conditions (defined as whether the intakes of energy and protein satisfy the requirements). We estimated the energy balance (energy intake minus its expenditure) and the protein balance (protein intake minus its requirement) of the monkeys on Kinkazan Island every month over the course of 1 year (2004--2005) in order to verify Nakagawa's conclusions. Like Nakagawa, we found that the energy balance of the monkeys in the fall was higher than in the summer and winter, whereas the protein balance in the fall was higher than in the winter.