Indonesian Conservation Media Center

The Primates, Dwellers of Siberut

(2 Juli 2010)

Mentawai archipelago is a constellation of islands in western part of Sumatra, consisting of 4 major island: Siberut Island, North Pagai Island, South Pagai Island, and Sipora Island. Siberut Island is the largest island, 4.480 km² wide. This island is less than 100 km from West Sumatra beaches. Administratively, these islands are included into Kepulauan Mentawai Regency and are divided into two districts, North Siberut district and South Siberut District.

Mentawai archipelago was separated from Sumatra Island around 200 thousand years ago. This separation causes flora, fauna, ecosystem uniqueness and original Mentawai culture. Most of the fauna that dwell these islands are primates. There are four species of primate endemic to Mentawai, those are: Bilou (Hylobathes klosii), Joja (Presbytis ptenziani), Bokoi(Macaca pagensis), and Simakobu(Simias concolor). Forest clearings for HPH (Hak Pemilikan Hutan/ Forest Ownership Rights) or palm plantation over the years have resulted in habitat damages of these four primates, threatening their survivals. Based on the IUCN Red List, these four species have different risks of extinction, critically endangered for Bokkoi, endangered for Simakobu, and vulnerable for Joja and Bilou.

            Protection efforts for these four species have been done by the Indonesian Government by issuing several Letter of Decree, among others are Minister of Agriculture Letter of Decree No. 327/Kpts/Um/7/1972 for Simakobu (Simias concolor),  protection Minister of Agriculture Letter of Decree No. 537/Kpts/Um/12/1977 for Bokkoi (Macaca pagensis) protection and Joja (Presbytis potenziani), and for Bilou (Hylobathes klosii) protection by issuing Wildlife Ordonance and Protection No 134 and 226, authorized by Dutch Colonial Government. Besides that, the conservation efforts for these four primates also include the establishment of Siberut Island as a conservation area, starting from wildlife reserve foundation, and then it became nature reserve and in 1980 WWF proposed that Siberut Island made into Biosphere Reserve because of the ecosystem uniqueness of the island. In the next development, Siberut Island was then appointed as Siberut Island National Park, based on the Minister of Forestry Letter of Decree No. 407/Kpts-2/1993.

Below are short descriptions of the four primates mentioned above : 

1. Bilou (Hylobathes klosii)

This kind of primate has the characteristics as follows: it has a sparse jet black hair; there is a membrane between its second and third fingers. This kind lives in groups consisting of male and female parents and young children. According to Tenaza, 1982 in Zuwendra (2001), Bilou is a monogamous primate with family size of 3-4 members and a group consisting of 11 individuals.

This kind of primate spends most of their time in the trees and they rarely go down. Their diet consists of fruits from Ficus sp trees, nibung trees, liana, etc. this fauna uses its hands and arms to move and jump from one tree branch to other branches. This kind lives in a small part of the four islands in Mentawai archipelago. According to LIPI 1994 in Zuewndra (2001), Bilou are found mostly in mixed primary forests and primary dipterocarpaceae forests (66,66%) and secondary forests (33,34%).
2. Simakobu (Simias concolor)

Simakobu is a monkey with short tail, a short fat baody and all its limbs have the same length (Zuewndra, 2001). The hair is dark grey or golden and they live in groups. One group consists of 3-15 individuals. This type is a leave eater and they live in freshwater swamp forests, brackish forest, and lowland forest.

 

3.         Joja (Presbytis potenziani)\

This animal has a shiny black back, dark brown stomach, around its neck and face is white. It has a soft and long tail and it moves using its four legs. Its diet consists of fruits, leaves, seeds, flowers and other parts of plant. This kind of primate lives in the trees in primary and secondary forests.

Simakobu is a monkey with short tail, a short fat baody and all its limbs have the same length (Zuewndra, 2001). The hair is dark grey or golden and they live in groups. One group consists of 3-15 individuals. This type is a leave eater and they live in freshwater swamp forests, brackish forest, and lowland forest.

3.         Joja (Presbytis potenziani)

This animal has a shiny black back, dark brown stomach, around its neck and face is white. It has a soft and long tail and it moves using its four legs. Its diet consists of fruits, leaves, seeds, flowers and other parts of plant. This kind of primate lives in the trees in primary and secondary forests.

4. Bokkoi (Macaca pagensis)

This kind of Primate has dark hair color and white cheeks, contrasts to its hair. They live I groups consisting of 30 individuals. This kind has a various food sources, starting from fruits, leaves, until insects and shellfishes from mangrove forests. This fauna lives in primary forests from mountainous to swampy areas.

 

 

Source:

Zuwendra. 2001. Makalah Primata Endemik Mentawai di Siberut dalam Konservasi Satwa Primata. Faculty of Veterinary and Faculty of Forestry, Gadjah Mada University. Yogyakarta