Case Report of Infanticide by a Wild Long-tailed Macaque (Macaca fascicularis)

Infanticide is common among non-human primates. There are a few cases of infanticide reported in wild groups of the genus Macaca, but in Macaca fasicularis, it is only reported under captive conditions. The present report describes the first case of infanticide observed in wild M. fascicularis in Pangandaran Nature Reserve, West Java, Indonesia, in which an adult male was seen carrying and repeatedly biting an infant. The male attacked a female (presumably the infant’s mother) who approached him. We discuss several explanations for the observed infanticide from the perspectives of sexual selection and socio-pathology.