We observed an enclosure group of Yakushima macaques (Macaca fuscata yakuii) to examine the embracing behaviors which is known as the social custom of wild Yakushima macaques. As a result of observing the group composed of 3 adult males, 4 adult females, 2 adolescent males, 4 juvenile males, 1 juvenile female, 1 infant male, and 1 infant female at Okinawa Zoo and Museum in March, 2023-2024, Yakushima-type embracing characterized by ventro-lateral embraces accompanied by kneading another’s fur by opening and closing the palm was observed. Unexpectedly, the following infrequently observed phenomena and behaviors in wild/provisioned groups of Japanese macaques were also observed despite the short observation period (38 h 28 min for a total of 6 days): female dominance over male, sexual prematurity, mutual grooming, grooming chain involving four individuals simultaneously, threat via self-wrist biting, tree-shaking by adult female, pirouettes, self-suckling, grasping male genitals, and sucking male genitals. Some of these could be explained by high nutritional status (sexual prematurity) and high social stress (threat via self-wrist biting and self-suckling) under captive conditions or by recent social change (female dominance over males and grasping male genitals). Given the ease of individual identification by artificial marking, the enclosure group of Yakushima macaques in this zoo can be suitable not only for study focused on infrequently observed behavior such as those reported here, but also for training student to collect data on frequently observed behaviors, such as social grooming and aggression.

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