Abstract # 107:

Scheduled for Friday, August 18, 2006 09:30 AM-09:45 AM: Session 10 (Regency East #2) Oral Presentation

Infanticide in Japanese macaques (MACACA FUSCATA): When does it occur?

K. Yamada and M. Nakamichi
Department of Comparative and Developmental Psychology, Graduate School of Human Sciences, Osaka University, Suita, Osaka 565-0871, Japan
     Infanticide by a male has evolved as a reproductive strategy. Japanese macaques are seasonal breeders and have a multi-male and multi-female social structure. Infanticide in Japanese macaques is extremely infrequent because the infanticidal male can only mate with the victim’s mother during the mating season, females mate with males promiscuously, and the infant’s father and other resident males remain in the group and defend the infant from infanticide. Here, we report our observation of infanticide, summarize five previous reports of infanticide in Japanese macaques, and summarize when it is likely to occur. We observed and video-recorded that a non-resident adult male killed a 4-month-old unweaned infant in a free-ranging group of Japanese macaques. The infanticidal male appeared for the first time. It occurred a few weeks before the mating season began, so the victim’s mother soon resumed estrus and gave birth in the subsequent birth season although we did not observe the male mating with the mother. The top-ranking adult males had disappeared a few months before the infanticide. In the five previous reports, as well as our observation, we pointed out that infanticide in Japanese macaques was likely to occur (1) in the pre- or early-mating season, (2) when there was a threatening male who was least likely to be the infant’s father, and (3) when there were no resident males to defend the infant against attacks.