Infant and Juvenile-Directed Care Behaviors in Adult Toque Macaques, Macaca Sinica

Abstract

The identity of care-givers, and the distribution of care to young are examined in a free-ranging polygynous primate, Macaca sinica. Care behavior is used as one measure of investment in young. There is no evidence that dominance rank influences offspring sex, but high-ranking mothers provide more care to newborn infants than do low-ranking mothers. Mothers provide more care to infant and first year sons than to daughters. This supports Dittus's suggestion (1979, 1980) that mothers should schedule care to sons and daughters differently, providing high levels of care to sons before they emigrate from the natal group. Care to daughters is low per unit time, but continues over a long period because daughters remain in the natal group. Adult females, other than the mother, tolerate, groom and support young. These behaviors are low cost, relative to the high cost behaviors of nursing and carrying, which only mothers provide. Young tend to associate with adult female relatives. Unlike male-biased maternal care, adult female care is biased towards female young; and female young return care more than do male young . Adult female rank is positively correlated with the amount of support adult females provide to female young, and the amount of grooming they receive from female young. Adult female rank has no effect on any measure of association between adult females and male young. Taken together these findings suggest that reciprocal altruism has been important in shaping adult female interactions with young. Adult and subadult M. sinica males direct the low cost, affiliative behaviors of hugging, carrying and grooming towards male infants; and direct aggressive behaviors towards female infants. I suggest that the distribution of behaviors reflects their value to male and female young. Affiliative behaviors to male infants, and aggressive behaviors to female infants serve to channel infants into association with adults from whom they can learn appropriate sex-typical behaviors, and as such benefit both male and female infants. High cost care behaviors of support in agonistic interactions, and protection are provided only by the adult male, and are provided to male and female young equally.