Using Fecal Hormones to Determine Reproductive State and Female Choice in Wild Vervet Monkeys (Chlorocebus pygerythrus)

This study aimed to assess the feasibility of using fecal hormones to identify female reproductive state in wild vervet monkeys (Chlorocebus pygerythrus) in order to gain insight on changes in female mate choice. We followed a single study group with 16 adult/subadult females at Lake Nabugabo, Uganda over a 5-month field season in 2022. During this time, 248 fecal samples and 309 hours of behavioral observations were collected and used in analyses. Mean gestation length from hormonal data was 164.33 ± 18.09 days (range 134 – 187 days) based on six females that conceived during the study. However, gaps in fecal sample collection highlight that, while feasible, greater sampling effort is needed in future studies using fecal hormones. Generally, behavioral results indicate females displayed more proceptive and receptive behaviors towards males while ovulatory and appeared to prefer high-ranking males. However, there was no effect of female dominance rank on mate choice.