In addition, sexually mature male Japanese macaques suffer higher mortality than females, probably because they engage in more risky behaviours such as greater amounts of inter-group mobility and aggressive competition (e.g., Fedigan and Zohar, 1997 and Sugiyama, 1976). These factors combine to limit the number of adult males, relative to adult females, that co-exist in Japanese macaque multi-male/multi-female groups. The same situation characterizes many macaque species