A Newly Reported Tactile Gesture for Grooming Initiation in Japanese Macaques ( Macaca fuscata ) at Awajishima, Japan

ABSTRACT Communicative signals such as vocalizations, facial expressions and gestures enable animals to communicate their intentions to other individuals. As one of such signals, primates often perform grooming solicitation (hereafter, solicitation), in which an individual lies in front of another or shows its body part to elicit grooming from other individuals. In a free‐ranging group of Japanese macaques ( Macaca fuscata ) at Awajishima, Japan, another form of gesture for grooming initiation is sometimes observed, which has been unreported in this species. In this behavior, which is named ‘tapping’, an individual softly touches another individual, often followed by grooming between the two. In this study I investigated how tapping is used in this group in comparison with solicitation, especially focusing on its function and social relationships between the signalers and the receivers. In most cases, tapping was followed by grooming but no other affiliative interactions. While solicitation was used by both males and females, tapping was observed almost exclusively between adult females. Compared with solicitation, tapping was more likely to occur between less affiliative, non‐kin‐related dyads and more likely to be directed from the dominant to the subordinate. These results suggest that tapping functions as a tactile gesture to initiate grooming, especially with more weakly‐bonded partners. Finally, social network analysis revealed that tapping was preliminarily used among the highest ranked females. Tapping might be a cultural behavior of the Awajishima group, potentially related to specifically high social tolerance of this group.