Primiparous chimpanzee mothers: behavior and success in a short-term assessment of infant rearing

Assessing the maternal competence of a first time chimpanzee mother can be difficult. Managers will often attempt to leave infants with their mothers as long as possible in an effort to provide the infant with natural maternal care, as well as give the mother some maternal experience. However if the mother is not capable of properly rearing the infant, this process can be dangerous to the infant. Objective criteria to measure and predict a mother's abilities would be useful. Few studies have examined the behavior patterns of successful and unsuccessful chimpanzee mothers, and the findings of those studies were descriptive, with little or no quantitative results. In the current study, 23 primiparous chimpanzees were examined for differences in behavior between successful and unsuccessful mothers over a period of several weeks postpartum. Mothers were classified as unsuccessful if their infants required nursery-rearing due to inadequate maternal behavior. Only 7 of the 23 mothers in this sample were classified as unsuccessful. Successful mothers engaged in appropriate carrying behaviors more often than unsuccessful mothers. Additionally, successful mothers engaged in fewer inappropriate carrying behaviors and infant avoidance behaviors. However, successful mothers did engage in these behaviors, albeit less frequently, indicating that the presence of these behaviors alone is not indicative of inadequate maternal ability. Maternal behaviors, infant behaviors, and mother-infant interactions showed no change in frequency over a period of 3 weeks for either successful or unsuccessful mothers, with the exception of infant crying. Infants of successful mothers cried less frequently over time, indicating that their mothers may have been learning how to meet the needs of their infants over the course of time. These results provide some of the first empirical data on the behavior patterns of successful and unsuccessful primiparous chimpanzees. This information can be used to aid colony managers in assessing the maternal ability of primiparous chimpanzees. (C) 2003 Elsevier B.V. All rights reserved.