We compared the ranging behavior between males in group and isolated males of Macaca fuscata yakui to clarify the constraints by belonging to groups.

In Yakushima, males belonging to groups often isolated from their group temporarily (Otani et al, in preparation). We compared ranging speed, preference of habitat use and degree of meandering between males ranging with group and males ranging alone. Males ranging with a group would range at lower speed than they do alone because the group includes females and juveniles who are smaller than males. Also there would be the difference of preference of habitat use because males and females have different levels of food requirements and the ability of overcoming the physical obstruction. Because males ranging alone can use even a small food patch which supplies only a little amount of food for group, they would use greater number of patches per day. Therefore they would have more tortuous tracks.

These differences indicate that males would be constrained their ranging behavior by ranging with group. By observing males ranging alone, the optimal strategies of males’ ranging behavior and the degree of constraints within groups can be clarified. To reveal the advantages and the disadvantages of group living is conducive to understandings the meanings of forming group.