Physiological Cycle of Adult Females and the Sex Identification of Juveniles in Hainan Gibbons: A Preliminary Study

In this study, feces samples were collected from 7 individuals in Hainan gibbon (Nomascus hainanus) family group C by through non-invasive methods, and the levels of progesterone and testosterone were analyzed by high-performance liquid chromatography mass spectrometry. The results showed that the menstrual cycle of adult females in Hainan gibbon group C was 32±3.6 days and the duration of the menstrual period was 10±2.4 days. There was no significant difference in progesterone levels between individuals of different age and sex classes, no significant periodicity in the change of testosterone in the feces samples of Hainan gibbon group C, and no significant difference in the level of testosterone between individuals of the same sex and age. However, there was a significant difference in testosterone levels between adult males and adult females. By comparing the levels of testosterone in different individuals, it could be hypothesized that both juveniles in group C may be males. The results show that the circadian cycle of adult females and the sex identification of juveniles in Hainan gibbons may be inferred from differences in fecal progesterone and testosterone levels.