Leakey Foundation Final Report
Female mating strategies in tufted capuchin monkeys (Cebus apella nigritus) Barbara Tiddi Postdoctoral Scientist, Cognitive Ethology Laboratory, German Primate Center (DPZ), Goettingen, Germany. Brief Summary The present project investigated female mating strategies in tufted capuchin monkeys (Cebus apella nigritus, synonymous with Sapajus nigritus; Lynch-Alfaro et al., 2012). The specific focus was to determine the extent to which wild tufted capuchin females solve conflicts of reproductive interest with both sexes by exploring the following aspects of female mating strategies: 1) the extent to which female sexual and mating behaviour (i.e., proceptive behaviours and copulations) are hormonally driven; and 2) the adaptive function of female sexual behaviour within the context of intersexual conflict and intrasexual competition. As previously found in a captive group (Carosi et al., 1999), we demonstrated via hormone analysis that female sexual behaviour (hereafter proceptive behaviours) is highly associated with the female fertile phase, and thus our results corroborate the contention that proceptive behaviours among tufted capuchin females are a reliable indicator of ovarian function. Similarly, mating activity was highly concentrated during female fertile periods, resulting in a relatively short window for copulations occurring around the day of ovulation. Thus, we found an overall strong link between female sexual behaviour and progesteron levels. When considering the adaptive function of female proceptive behaviours, such behaviours varied according to the probability of ovulation. In contrast, female proceptivity did not vary with measures of female reproductive quality (e.g., fecundity, age and dominance rank). These findings are in accordance with the graded-signal hypothesis (Nunn 1999), suggesting that females tend to reduce male-imposed constraints (e.g., infanticide) by confusing and biasing paternity. Males responded to these signals by synchronizing their mating effort around the female fertile phase; alpha males in particular intensified their copulations during those days with a high probability of ovulation. Overall, as suggested by Janson (1984), copulations seem to be closely associated to the timing of ovulation more for alpha males than for subordinate males. Finally, although females often overlapped in