The southern pig-tailed macaque (Macaca nemestrina), also known as the Sundaland pig-tailed macaque and Sunda pig-tailed macaque, is a medium-sized macaque that lives in southern Thailand, Malaysia, and Indonesia. It is known locally as berok.

As with other Macaca species, males are larger than females; while males are measured at 50–58 cm (20–23 in) in length and 5–12 kg (11–26 lb) in weight, females are measured at 38–48 cm (15–19 in) in length and 4.5–6 kg (9.9–13.2 lb) in weight. This macaque 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.

M. nemestrina is mainly terrestrial, but also a skilled climber. Unlike almost all primates, these macaques love water. They live in large groups that split into smaller groups during daytime when they are foraging. They are omnivorous, feeding mainly on fruits, seeds, berries, cereals, fungi, and invertebrates. A study in peninsular Malaysia found them to be the primary, and perhaps the only, seed dispersers of the rattan species Daemonorops calicarpa and Calamus castaneus.

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. Female gestation lasts around 5.7 months. She will give birth to one infant every two years. Weaning occurs at 4–5 months. Sexual maturity is reached at 3–5 years.

This macaque is mostly found in rainforest up to 2000 meters, but will also enter plantations and gardens. It is found in the southern half of the Malay Peninsula (only just extending into southernmost Thailand), Borneo, Sumatra and Bangka Island. There are reports of the species having been present in Singapore before 1950, but these were likely escaped pets. The only pig-tailed macaques in Singapore today are introduced monkeys. In Thailand, they have been trained for 400 years to harvest coconuts. 

Southern Thailand wild population - Hala Bala

Working monkeys - Southern Thailand in Pattani, Surathani and other provinces

Borneo Population - Tabin. Sepilok and Danum Valley Sabah Malaysian Borneo