Social Factors Influencing Within-Group Vigilance in Japanese Macaques ( Macaca fuscata)

Abstract

The present study investigated vigilance in Japanese macaques (Macaca fuscata) in reference to some social factors. Previous studies have suggested that social factors among conspecifics should be important for vigilance in primates. This study explored the relationship between individual's social rank and vigilance in estrous and non-estrous periods in female Japanese macaques. With a video camera, I recorded vigilance of 23 females among approximately 170 individuals of Arashiyama E-troop. The results were as follows. High degree of vigilance was observed in three conditions, 1)females in estrous period regardless of the rank, 2)low-ranking females in non- estrous period, and 3)females in estrous period consorting with low-ranking males. These results indicate that social relationship is an important factor which affects the degree of vigilance in female Japanese macaques.