Ecological studies on food conditions and cognitive ability of Japanese macaques over food

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This project aims to clarify how individual Japanese macaque recognize the distribution of foods in the wild and how each individual uses these knowledge as foraging strategies. Field studies have been conducted on the well habituated (non-provisioned) Japanese macaques inhabiting the warm-temperate forest at Yakushima Island, Japan. Data were collected by focal-sampling and scan-sampling methods on activity rhythm, feeding time budget, individual day range, travel route, choice of food patch, duration of visit, and inter-individual relationships in each season (Spring, Summer, Autumn and Winter) . These data were analyzed in relation to phenology of fruit measured by the line-transect methods. The results suggest that the wild Japanese macaques (Macaca fuscata yakui) use two foraging patterns (Goal-oriented and Opportunistic) according to the availability of high-quality foods (fruits or insects) . The goal-oriented foraging is observed frequently during the fruiting period (Autum-winter) , when macaques form a cohesive group, travel long distance and continuously visit the particular fruiting trees. The opportunistic foraging is usually observed during the non-fruiting season (winter-spring) , when they disperse to forage diversed food items individually.Not only food conditions but also sex, age or social status of each individual influence the choice of foraging strategies. Individual foraging patterns reflect life history and social recognition of Japanese macaques. The goal-oriented foraging may have evolved as an optimal strategy between feeding and reproduction, which are strongly influenced by individual social recognition.