Sexual behavior in a captive group of pigtailed monkeys (Macaca nemestrina)

Sixteen pigtailed monkeys (Macaca nemestrina) were studied to determine patterns of estrous cycles and sexual behavior. The average estrous cycle lasted 42 days, the average tumescent period 21 days, and the average quiescent period 17 days. Results are consistent with those obtained from studies of individually caged monkeys. The mean length of gestation for five live births was 174.6 days with a range of 167 to 179 days. Patterns of heterosexual, homosexual, and self-oriented sexual behavior are described and quantified.