1Department of Anthropology, School of Biomedical Sciences, Kent State University, 2Department of Anthropology, Emory University
Saturday 3:30-3:45, Grand Ballroom II
Copulating during ovulation is critical to both male and female reproductive success. However, male knowledge of ovulation may not always be advantageous for females, as it could hinder mate choice or promote harassment. White-faced sakis show no obvious physical or behavioral signs of ovulation, although males often sniff female genitalia prior to copulation. We collected data on free-ranging white-faced sakis at Brownsberg Naturepark, Suriname in order to assess whether male copulatory decisions reflect knowledge of ovulatory timing. We recorded all occurrences of copulations and genital inspections for five females over a 17-month period. Fecal samples were also collected and radioimmunoassayed for estradiol and progesterone in order to determine female reproductive status. We found that males copulated throughout the female reproductive cycle, although the association between copulations and reproductive state varied between dyads. Only one male-female dyad copulated significantly more than expected during ovulation, although 80% of dyads copulated less frequently than expected with pregnant females. Genital inspections were distributed randomly with regard to reproductive state. However, males were more likely to mate with cycling females than with non-cycling females after genitally inspection. Regardless, males were no more likely to copulate with females while ovulating than during other times of the cycle. Our data suggest that while white-faced saki males gain some olfactory information on female hormonal status, they do not make entirely accurate decisions with regard to copulation timing. Male sexual experience and pair-bond familiarity may also play a role in the ability to detect female reproductive status.
This study was funded by NSF (BSC-0925122) and The International Primatological Society’s Research Grant.