抄録
Female primates signal their reproductive state through behavioral, visual (e.g. swelling size), auditory (e.g. copulation calls) and olfactory (i.e. vaginal odorant compounds) cues. To date however, studies have generally focused on ovulatory signaling, and the multimodal advertisement of pregnancy is still largely uninvestigated. We aimed to determine if female Japanese macaques (Macaca fuscata) advertise their pregnancy via changes in behavioral, visual and auditory sexual signals, and the role of these signals in male mating decisions. We combined digital photography, behavioral and endocrinological (progestogen and estrogen) data from 5 females, for three one-month periods: pre-conceptive period, first month of pregnancy and second month of pregnancy. We found that males and females did not copulate during pregnancy, and that most sexual behaviors (e.g. male and female approaches, male holding behaviors) decreased between the pre-conceptive and the pregnancy period. Female faces became significantly darker from the pre-conceptive period to pregnancy, and face redness significantly decreased between the 1st and 2nd month of pregnancy. Estrus call frequency was significantly lower during the 1st month of pregnancy compared to the pre-conceptive period and the 2nd month of pregnancy. The ratio of female sexual steroids during pregnancy was correlated to estrus call frequency. Our results suggest that pregnancy in Japanese macaques is signaled multimodally (i.e. behavioral, visual and potentially auditory signals), which is likely to provide benefits to both sexes. Females and males could decrease the overall cost of mating, with females allocating their energy to fetal growth, and males focusing their reproductive effort on cycling females.
