The Crab-eating macaque, Macaca fascicularis, or Long-tailed macaque is a primate native of South-east Asia. The history of these macaques on Mauritius is mostly undocumented, but they are believed to have been introduced by either Portuguese or Dutch sailors. The animals form matrilineal and matriarchal social groups with male members leaving the group upon reaching puberty. Adult macaques measure between 38 to 55 centimeters, and sexual dimorphism is present in the species with males weighing 5 to 9 kilograms and in contrast to females weighing 3 to 6 kilograms. Their upperparts are dark brown with light golden-brown tips while their underparts are light grey. They have a dark grey and brown long tail which they use for balance when making jumps. Males and females both bear whiskers on the cheek, while only the male has a moustache. They have a cheek pouch used to store food when foraging.
Crab-eating macaques are adapted to a range of habitats, such as mangrove and swamp forests, agricultural areas and forests. They are opportunistic omnivores, with at least 50 percent of their diet consisting of fruit, nuts and seeds. They are also known to eat leaves, flowers, roots, bark as well as vertebrates such as bird chicks, lizards, frogs and fish, invertebrates and bird eggs. In mangrove habitats, the macaques prey on crabs among other things, giving them their common name.
Crab eating macaques are very social animals, living in groups of 5 to 60 individuals. Sexual maturity is reached at 4 years for females and 6 years for males. In mating, males sometimes groom females to increase their chances of sexual activity. High-ranking females are more successful at reproduction than lower-ranking females. The female has a gestation period of 162 to 193 days and will bear one infant. They will then nurse their young for approximately 420 days.
The crab-eating macaque is listed as ‘Least Concern’ in the IUCN Red List of Threatened Species. The crab-eating macaque is common throughout its range, in both native and introduced habitats. It is also recognized as an invasive species and a threat to biodiversity in several locations.
Owing to the veneration of Hanuman, macaques found around Hindu temples – where they can find food - are often considered sacred.