Behavioral correlates of reproductive success in a pigtail macaque breeding colony

Abstract

Data on social and spatial behavior from a sample of 21 female pigtail macaques (Macaca nemestrt'na) were analyzed to identify behavioral correlates which could be used to predict reproductive success, problem pregnancies, and adult female mortality in a primate breeding colony in the subsequent year. Two spatial measures of sociability, amount'of time and number of other individuals involved in sitting associations, were found to be related to future adult and infant survivorship.With the rising interest in the development of breeding colonies for primates in the United States, there is a strong need for information relating to repro· ductive success under colony conditions. Van Wagenen (1972) has used the breeding records from a rhesus macaque (Macaca mulatta) colony to describe characteristics of successful births, abortions, stillbirths, early neonatal deaths, and maternal deaths. Sackett, Holm, and Landesman-Dwyer (1975) analyzed breeding colony records for pigtail macaque (Macaca nemestrina) females. They found that the weight of the mother, medical treatment history, number of years in the colony, number of days in a stable breeding group, and previous reproductive history all correlated with pregnancy outcome and could be used to predict the success of future pregnancies at a better than chance rate. Analysis of squirrel monkey (Saimiri sciureus) breeding records has shown that length of time in the colony and diet are important factors in reproductive success in this species (Rosenblum, 1968).While these studies seem to indicate a trend toward greater use of breeding colony demographic and medical records, there still is a paucity of behavioral data to aid in understanding the determinants of pregnancy outcome in primates. Long-term studies of free-ranging rhesus monkeys on La Parguera indicate that behavioral differences between females are correlated with differences in reproductive success, with infants of higher ranking females having a greater chance of surviving than infants of lower ranking females (Drickamer, 1974). Similar studies relating reproductive success to the particular conditions of the breeding colony are lacking, however.