Responses to dying and dead adult companions in a free-ranging, provisioned group of Japanese macaques (Macaca fuscata)

Abstract

We report behavioral responses to four dying and dead adult companions (two aged alpha males, one high-ranking adult male, and one aged, high-ranking female) in a free-ranging, provisioned group of Japanese macaques, with particular interest in whether external, visible bodily damage to the deceased individuals and social affinity with them influenced responses of group members. All but one moved away or stayed away from the dying or dead individuals when they noticed maggots on them, likely indicating an aversion to maggots (Cases 1, 2, and 3). However, some individuals remained near the corpse of an adult male that had no noticeable external damage, and a juvenile female whose mother was his most frequent proximity partner groomed him (Case 4). One adult female who ate maggots while grooming the dying alpha male (Case 1) and most individuals who remained relatively close to another alpha male’s rain-drenched dead body (Case 2) were also affiliated with those two alpha males prior to their deaths. We conclude that Japanese monkeys have a strong tendency to avoid dying and dead adult companions already infested with maggots but that some individuals with social affinity with the deceased may contact or at least remain near the latter for some time. We discuss monkeys’ possible perceptions when encountering corpses, in relation to non-human primates’ awareness of death.