Mothering Style and Infant Behavioral Development in Yunnan Snub-Nosed Monkeys (Rhinopithecus bieti) in China

Considerable variation in mothering styles is found among primate species, which may be directly related to species-typical differences in social structure, dominance style, patterns of infant development, and rates of intragroup aggression. We predicted that, as egalitarian Asian colobines, mothers of Yunnan snub-nosed monkeys (Rhinopithecus bieti) would adopt a mothering style characterized by low restrictiveness and low rejection. We followed six mother-infant dyads in a provisioned group of Rhinopithecus bieti inhabiting the Baimaxueshan National Nature Reserve, Yunnan, China, and collected 717.2 h of observational data on maternal care and infant development. In the first month after birth, infants were completely dependent on their mothers for nutrition and movement. They began to locomote clumsily during their second month of life. Mothers restricted the movements of their infants only during their first 2 mo of life. Maternal rejection occurred infrequently and never exceeded a mean of two events per hour for a given infant over any 1-mo period. Most rejections were mild, and did not result in a cessation of nursing. Infants were not weaned when they were 12 mo old. Our study offers support for the contention that females of Rhinopithecus bieti adopt a relaxed mothering style in caring for offspring during their first year of life.