嵐山・幸島におけるニホンザルの死産の報告

抄録

Here, we have reported two cases of diurnal stillbirths in free-ranging groups of Japanese macaques (Macaca fuscata), Arashiyama and Koshima groups. One infant was born prematurely and in breech position, while the other seemed to be a full-term infant born in front position. The two mothers had little interaction with other members of the group throughout parturition. The group members, except for juveniles, also showed little interest in the mothers.
The mother of the infant born in the breech position licked the body of the infant, as in the case of live births. Moreover, both mothers carried the infants ventrally. However, the two mothers also showed behaviors that were different from those usually observed after a live birth. The mother of the infant born in breech position tore parts of the infant's skin and ate them. The other mother dragged the infant by grabbing the umbilical cord.
Previous studies have reported that mothers carry infants that died after birth, but it was unclear whether interactions with live infants were required for such maternal behavior. Our observations suggest that some maternal behaviors can be observed even when the infants die before parturition. At the same time, the cases reported by us show the possibility that infants born dead may influence the expression of certain unusual behaviors.