Abstract
It has been proposed that the rate of scratching may be a good behavioral measure of social tension. A case study was conducted to examine the expression of social tension, with particular emphasis on scratching rate, during the intergroup transfer of a 5-year-old male Japanese macaque (Macaca fuscata). This male was frequently involved in agonistic interactions during the course of transfer from the natal group to a neighboring group. Mounting before grooming sessions was frequently observed at the first stage of transfer. During the course of immigration, scratching rate decreased gradually when the male was not in close proximity to members of the neighboring group. Scratching rate was lower when the male was receiving grooming compared with before or after a grooming session. A decrease in scratching rate before and after grooming sessions was found when the male was in the natal group, while no such tendency was found when he was in the neighboring group. It is suggested that scratching can be used as a behavioral measure of social tension both in the field studies as well as in the captive studies.
