| Reproductive maturity is affected by body condition and social environment in primates. Prior studies have revealed that most female rhesus macaques have their first birth at four years of age and that a minimum body weight is a necessary, but not sufficient, condition for achieving first pregnancy. However, studies to date have not explored the links between social behavior, sexual maturation, and reproductive outcome. This two-year investigation focused on: (1) exploring the proximate behavioral and morphometric requirements that affect the reproductive strategies of early or delayed first age of conception and postpartum recovery in rhesus macaques, and (2) primiparous females' infant development and survivorship. The study was conducted with twenty-two nulliparous focal females, eleven of which conceived, from Group M at the Caribbean Primate Research Center (CPRC), Sabana Seca Field Station, Puerto Rico.; The results revealed that the females' foraging time did not influence their body condition before conception or after parturition. Generally, morphometric measurements demonstrated less of an influence on conception than did social determinants, but younger females that advanced their age of first conception were found to have a greater body mass index than those that remained barren. Stress was a determining factor affecting first conception, with high ranking females exhibiting a greater likelihood of conceiving and an advanced age of first conception. Higher frequencies of mounts with intromission by adult males were recorded among females that conceived, with most of these females having a high dominance rank.; Higher levels of maternal protectiveness were found among low ranking females, which were also attacked more frequently. Maternal rank, age, and maternal foraging time, as well as the infant's sex or time spent on the nipple, had little influence over infant survivorship, development, or maternal postpartum recovery during the first three-months postpartum. However, infant development was positively related to maternal condition prior to conception and maternal postpartum recuperation was negatively correlated with increased maternal vigilance (alert time). In this study, stress seemed to be an important factor influencing the development of young females, including their reproductive maturation, first pregnancy, and postpartum recuperation. |
