| Abstrakt: |
Knowledge of species‐typical reproductive endocrinology profiles is crucial for testing hypotheses pertaining to the evolutionary history, reproductive parameters, and life history of a species, and for managing the well‐being of individual animals in human care. Large‐scale empirical measurements of ovarian hormones, however, are rare for most primate species, including orangutans. In this study, we used enzyme immunoassays (EIA) to quantify estrogen (estrone conjugates; E1C) and progesterone (pregnanediol‐3‐glucuronide; PdG) levels for 98 cycles in 7 cycling zoo‐housed female orangutans (10–43 years old). We use a subset of these cycles (N = 44) to create the first composite menstrual cycle for orangutans, which serves as a valuable baseline for future comparative analyses and veterinary considerations. Similar to previous studies, we determined the mean ovarian cycle length of orangutans to be 29.7 days (N = 98 cycles), although we illustrate evidence of both intra‐ and interindividual variation in ovarian steroid production. Given that this study took place in captivity, we consider how energetic and psychosocial aspects of the zoo environment, such as greater food availability and potential stress, may affect the reproductive physiology and sexual behavior of these females. Furthermore, we discuss the role that age and genetic background may play in producing variability. Finally, we test whether ovarian hormone levels correlate with the reproductive behaviors of these female orangutans using associated behavioral data. Our results suggest that matings are more common during the periovulatory period than outside of it, but do not support a consistent link between hormonal indices of fecundability and mating behaviors in these individuals. Highlights: Similar to previous studies, we found captive female orangutans had an intermenstrual interval of 29.7 days (range: 22–42 days; N = 98 cycles).Females exhibited substantial intra‐ and interindividual variability in hormonal indices of cycle quality.Females were observed mating across their entire menstrual cycle, although matings during the periovulatory phase (POP) tended to be more common. [ABSTRACT FROM AUTHOR] |
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