抄録
Grooming in primates is influenced by many variables, such as kinship, gender, age, dominance rank, level of affiliation, or reproductive status. One study suggests that higher-ranking males and females groom the opposite gender less frequently and shorter than lower-ranking males and females in Barbary macaques (M. sylvanus). In Japanese macaques (M. fuscata), however, higher-ranking males groomed estrous females longer than lower-ranking males, and male dominance rank showed no correlation with the duration of grooming they received from estrous females. The grooming between females and males cannot be explained by a single variable such as dominance rank or estrus. Subsequent studies have suggested that complex mechanisms may influence grooming patterns between females and males. I conducted an investigation of the effects of multiple variables which can affect mating partner choice on female and male grooming duration in Japanese macaques. I selected eight females of different (estimated) ages and dominance rank as focal animals from a single group (Miffy) of Japanese macaques living in western Yakushima. I followed the focal animals every other day from October 16 to December 28, 2024, and recorded copulation and grooming with males over the age of eight using continuous sampling method and focal sampling (Total focal sampling time: about 279 hours). Copulation occurrence, estrous status of females, dominance rank of females, age of females, dominance rank of males, age of males, affiliation of male (troop males vs non-troop males), and operational sex ratio (OSR, the number of estrous females per male) were analyzed as a variable that can influence preference of mating partner's choices. Copulation occurrence, estrus of females, age of females, affiliation of male, and OSR showed significant differences, but dominance rank of females, age of males, and dominance rank of males did not show significant differences in grooming duration between the opposite sexes grooming. Estrous females received longer grooming than non-estrous females, and non-troop males received longer grooming than troop males from females had copulated within 10 minutes. Among females had copulated within 10 minutes, older females received longer grooming than younger females from males. As OSR increased, estrous females had not copulated shorter and received less grooming from males. Some of the variables in this research showed an increasing grooming duration in accordance with variables preferred as mating partners in primates. I would like to suggest from this study that grooming between the opposite sexes may indicate preference as mating partners.
