Abstract A case of expeditionary ranging, ranging extensively out of the original home range, was observed in a Japanese macaque troop in Hieizan. Their original home range covered 499 ha, and during the one-month expedition, they ranged as far as 12 km from it. This troop did not suffer any demographic or environmental changes preceding the expedition. The distribution pattern of crops, distributed in thin, long patches along the edges of forest, and lack of adjacent troops seem to have facilitated the extensive expedition by this troop.

Key Words: expedition, ranging, philopatry, home range, Japanese macaque