Changes In Fecal Estrogen Levels And Sexual Behavior In Captive Sichuan Snub-Nosed Monkeys (Rhinopithecus roxellana) Following A Male Replacement

Rhinopithecus roxellana are generally seasonal breeders, although copulation can occur throughout the year. Previous studies suggest that estradiol modulates female sexual behavior during the mating season. However, the effects of social context on estrogen levels and behavior have not been fully explored. We studied the relationship between sexual behaviors and fecal estrogens in a group of captive R. roxellana during a period of social instability. We collected behavioral data for six months and collected fecal samples at 2–3-day intervals for four months spanning the mating and non-mating seasons, and analyzed fecal estrogen levels via RIA. Females showed clear cyclic solicitation and copulation peaks in the mating season, which corresponded with sharp peaks infecal estrogens. During the non-mating season, solicitation rates, copulation rates, and fecal estrogens were generally low. However, one non-pregnant female displayed a sharp peak in solicitations, copulations, andestrogens during the non-mating season 10–14 days after a male replacement. Our results provide preliminary evidence that social and behavioral changes affect estrogen levels in R. roxellana.