Macaca-pagensis, Pagai Island Macaque The Pagai Island Macaque (Macaca pagensis), also known as the Pagai Macaque or Bokkoi, is an Old World monkey that is endemic to the Mentawai Islands off the west coast of Sumatra. It is listed as critically endangered on the IUCN Red List due to its ever-shrinking habitat. It formerly included the overall darker M. siberu as a subspecies, but this arrangement is polyphyletic, leading to the two being classified as separate species. Both were formerly considered subspecies of M. nemestrina.
Pagai Island Macaque males are generally larger than females. The males’ body length ranges from 45-55 cm and females’ body length is around 40Â–45 cm. Tail length is 13-16 cm for males and 10Â–13 cm for females. Males are also heavier, weighing around 6Â–9 kg while females weigh 4.5-6 kg. Their backs have a dark brown coloration, and chestnut to pale ochre on the sides of the neck, the front of the shoulders and the underside of this species. Legs are brown and their arms, reddish brown. The face of a Mentawai Macaques is furless and black-skinned with brown eyes. They have cheek pouches to carry food while foraging.
Habitat and ecology
The macaques’ natural habitat is rainforest, but can also be found in riverine and coastal swamp-forests. It lives high above the forest floor in the canopy, forages between 24 and 36 meters and may sleep as high as 45 meters. The primary diet of the species is figs. They may split up into splinter groups to forage for food and to sleep. They will eat alongside groups of Mentawai Langurs. Macaca pagensis groups consist of around 5-25 indiviuals. There is typically a single male per group, along with adult females and their offspring. The male decides where to go and communicates this to the rest of the group with high-pitched cries. Roaming, solitary Pagai Island Macaques may challenge the dominant male for his position leading to aggressive fights. The natural predators of the species are the Crested Serpent Eagle and the Reticulated Python. When spotted the macaques will alarm the rest of the group with a short, gruff bark.
Females show fertility and willingness to mate by displaying their swollen and reddened genitals. Females crouch to initiate mating. The gestation period is between 5 to 6 months. A single offspring is born during the nighttime hours. The mother eats the placenta and licks the infant clean before morning. The mother and young share a close bond into adulthood.
Population and threats
The species’ primary habitat is on the Mentawai Islands 150 km off the west coast of Sumatra. They populate three of the four major islands in the chain (North Pagai, South Pagai and Sipora). Due to deforestation by immigrants from the Indonesian mainland the species is now listed as critically endangered on the IUCN red list. The primary reasons behind deforestation on the island are the clearing of large areas of land for cash crop and oil palm plantations, as well as commercial logging. As a result, the water levels in the forest rivers fluctuate to a much greater degree than before. The alternating flooding and low water levels has also caused an increase in the population of malarial mosquitoes