Grooming Partners of Immature Blue Monkeys (Cercopithecus mitis) in the Kakamega Forest, Kenya

I report results of a 4-year study, which profiles grooming partners of immature blue monkeys in a Kenyan rain forest. The analysis focuses on the degree to which mothers and offspring were preferred grooming partners and on sex differences in grooming partners. Subjects ranged in age from 0 to 6 years and were members of one study group in which kinship relations were known from long-term study. Immatures often had their mothers as the top-ranked partner. Even more reliably, however, adult females had their offspring as top-ranked immature partners. As offspring grew older, they tended to fall in the rank ordering of their mothers’ immature grooming partners, especially when younger siblings were born. Immature males had fewer grooming partners overall than female peers did. Thus, immature females diversified their partners more than males did, especially by establishing grooming relations with immature female partners. Immatures of both sexes had more female partners than expected by chance. Observed sex differences suggest that immature female blue monkeys may use grooming to cultivate relationships with long-term future benefits. It is less clear that the grooming of immature males functions in this way. Immatures of both sexes may also use grooming to maintain relationships of current value, to practice for future social exchange, and to keep clean, and some of their grooming may be in the primary interest of their partners, rather than themselves. In general, immature blue monkeys resemble the immatures of other catarrhine taxa in the way in which grooming is distributed among various partners.