Two cases of dead-infant carrying followed by mother-infant cannibalism in captive socially-housed Japanese macaques

Abstract

Interest is growing in attempts to understand animal behaviour towards dead conspecifics, especially among nonhuman primates. Although rare, infant-corpse-carrying is evident in many nonhuman primate species. However, in Japanese macaques it is relatively common, on average lasting several days. The combination of dead-infant-carrying for at least a day followed by filial cannibalism has been reported in one wild bonobo and two rehabilitant orangutan mothers. We report the first instances of dead-infant carrying followed by filial cannibalism in a monkey, housed socially. We present two cases of infant-corpse-carrying for 4 weeks, then filial cannibalism in a female Japanese macaque in two consecutive births. The individual (wild-born) was one of 25 individuals housed in a large outdoor enclosure (3800m²) with natural vegetation. We discuss the implications of our findings. Our observations are also unusual for the exceptionally long period of infant-corpse-carrying. On both occasions the mother carried the corpse until mummified: in 2011 for 29 days and in 2013 for 28 days. In 2011 she consumed all the dried flesh on day 28, yet continued carrying the skeletal remains intermittently for another day. In 2013 she chewed the corpse on day 23. This research complied with the Kyoto University Primate Research Institute guidelines for care and use of nonhuman primates. *The two first authors contributed equally to the research