The Southern pig-tailed macaque is a medium-sized macaque that lives in Southeast Asia. It has buff-brown fur, with a darker dorsal area and lighter ventral area. Its common name refers to the short tail held semi-erect, resembling the tail of a pig.
Southern pig-tailed macaques are found in the southern half of the Malay Peninsula (only just extending into southernmost Thailand), Borneo, Sumatra, and Bangka Island. They mainly live in dense rainforest, but will also enter plantations and gardens.
Southern pig-tailed macaques are mainly terrestrial, but also skilled climbers and often forage in the tree canopy. Unlike almost all primates, these macaques love water. They live in large groups that split into smaller groups during the daytime when they are foraging. There is a hierarchy among males, based on strength, and among females, based on heredity. Thus, the daughter of the alpha female will immediately be placed above all other females in the group. The alpha female leads the group, while the male role is more to manage conflict within the group and to defend it. Pig-tailed macaques are generally silent but they make a lot of vocalizations when they need to. They communicate with each other with the help of screams, squeals, growls, barks, screeches, and have the most common vocalization the sounds as 'coo'. Group members also groom each other, kiss, and feed together.
Southern pig-tailed macaques are polygynandrous (promiscuous), meaning that both the males and the females have multiple partners. Their breeding season takes place year-round. Females give birth to a single infant every two years and the gestation period lasts around 5.7 months. The young are born altricial and unable to feed and care for themselves independently. Mothers carry them, protect them, and nurse for 4-5 months. After one year of age, juveniles begin to associate more with other juveniles through rough tumble and playing activities. Young females become reproductively mature at 3 years of age and males start to breed when they are 4.5 years old.
The main threat to Southern pig-tailed macaques is habitat loss due to logging and agricultural development. They are also hunted for food, killed as crop pests or captured for the exotic pet trade.
According to the Restorasi Ekosistem Riau (RER) resource the total population size of the Southern pig-tailed macaques is 900,000 individuals. Currently, this species is classified as Vulnerable (VU) on the IUCN Red List and its numbers today are decreasing.
Southern pig-tailed macaques play an important role in their ecosystem, as they disperse seeds of various fruits and plants they consume.