Testing for Links Between Female Urine Odor and Male Sexual Behaviors in Japanese Macaques (Macaca fuscata)

Urine is involved in sexual communication in New World monkeys and lemurs, but most studies of the role of olfaction in sexual communication in Old World monkeys have focused on vaginal secretions rather than urine. We investigated whether female urine promotes male sexual behaviors (approaches and inspections of genital area) in Japanese macaques (Macaca fuscata). We used a sequential presentation paradigm in behavioral experiments, presenting unfamiliar female urine and control cotton swabs to males living in a social group with cycling females. We tested whether males (N = 3) showed more processing behaviors (licking, sniffing, tasting) toward female urine (22 stimuli per male from prefertile, fertile, and postfertile phases, based on urinary estrone and progesterone conjugate profiles) than control odor (8 stimuli per male). We then compared male sexual behaviors toward resident females pre- and post-exposure to stimuli and in relation to the females' reproductive status (perifertile, nonfertile, and pregnancy periods, based on fecal estrone and progesterone conjugate profiles). We found that males showed significantly more processing behaviors toward urine stimuli than to controls but that male behavior did not vary across urine samples from prefertile, fertile, and postfertile phases. Exposure to unfamiliar female urine stimuli did not modulate male approaches to and inspections of resident females at any stage of the female reproductive cycle. Although our study is limited by its small sample size, the results suggest that female urine contains compounds that males detect, but we found no evidence that female urine is related to male sexual behaviors.