The Project





Four Special Primates

Pig-tail snub-nosed monkey (Simias concolor)
Local name: SIMAKOBU

Simakobu still categorized groups monkey, but has a tail that is different from other monkey species. Simakobu short tail, approximately one third of the body length (80-130 mm).

Body color dark grayish brown, and some are golden. Hair color on the head and shoulder crest darker. Limbs blackish color. The face is black with a snub nose, body shape similar to the monkey (Macaca nemestrina). Ischial callosity (buttocks bearing) big and black. The male, bearing the buttocks are not separate, whereas the females are separated by a narrow slit.

While all other endemic primates of Siberut (Hylobates, Presbytis and Macaca) have congeners throughout SEA, the genus Simias is known only from the Mentawai islands. Simias concolor, the sole species of this genus, was formerly thought to belong to the genus Nasalis (i.e. Nasalis concolor) because of its affinity to the proboscis monkey.

Prior to the arrival of people on the Mentawai islands, the primary dangers to the Simakobu were local predators like birds of prey and presumably also large constricting snakes. Today man is its biggest enemy and hunting as well as logging and forest conversion are the main problems which threaten the survival of the species. Hunting is a particularly severe issue for Simias, as it is the preferred game of most Mentawai hunters. Logging and land conversion, however, seem equally grave dangers: Of all primates living in the Mentawai chain, Simias is the most sensitive one with regards to deforestation and shows significantly lower densities in logged forests than in unlogged areas; e.g. Pagai Islands: 2.54 vs. 5.17 animals per km².


Mentawai leaf monkey (Presbytis potenziani)
Local name: Joja (Siberut)

Body color on the dorsal and tail are black, whereas ventral pale to reddish brown. The forehead, chin and cheeks are white. Sections of about venereal (genital) is yellowish white and parts of genitals male (scrotum) overgrown with white hair.

Joja is active in the daytime (diurnal) and occupies a middle layer of the forest until the top (arborel). They live in territories which actively defended the invasion of other groups. If while browsing you will hear the sound of surprise, like a scream, the sound of guns, or dogs barking, then the females will show a unique behavior. Feeling threatened by the existence of such votes, joja female will stop and hide, making it very easy for hunters to locate and arrest him. In contrast, male individuals will move away if there is anything that endangers himself. This behavior would be a very dangerous problem Mentawai langur population. Because of the frequency of female captured in the natural population growth become disrupted. Options generally sleep and lots of lush trees liananya. So that at night, the hunters easy to trap, archery and shooting.

CITES has included Presbytis potenziani to the Appendix I species (CITES 2008c) and the IUCN Red List classifies this primate as “Vulnerable (VU A1c+2c & B1+2ac)”, recognising that it faces “a high risk of extinction”. Considering the current threats and the fact that a 50 % decline is substantial, WHITTAKER recommends an upgrade of the species’ status to “Endangered”.


Mentawai Macaque (Macaca pagensis)
Lokal name : Bokoi (Siberut)

The macaque is found only in endmik Mentawai archipelago, thus also called monkey of Mentawai. This monkey moving with the four limbs (quadripedal) when interacting with the ground or on trees. However, the transition from tree to tree done by jumping.

Bokoi, has similar characteristics to the monkey. The difference lies in the color of cheek’s hair is white, body size is slightly smaller and darker color of the monkey. It has a tail longer than M.nemestrina but shorter than M.fascicularis. Brown crown, the hair on the forehead, shoulders and moderately long coat. Sideburns on his cheeks brownish gray and has clear boundaries. Together with the monkey during pregnancy, and children born generally only one tail.

In the dense forest bokoi male who became leaders repeatedly sounds the call to keep in touch with members of his group. Voice calls in the form of sound: 'Kof Kof Kof Kon Kon Kon Kon' is hard, also greeted repeatedly by members of the group.


Kloss Gibbon/Dwarft Siamang (Hylobates klossi)
Local name : Bilou/Siamang Edil (Mentawai)

Hylobates klossii, Kloss’s gibbon or Bilou, as it is called by the Mentawaians, is a primate species which was described for the first time in 1902, following a collecting expedition to the Mentawai Islands.

Dwarf strains of gibbon more melodic sound when compared to several other gibbon species. Duet between male and female is rarely done. Males are usually voiced one hour before dawn, while the female voice is more or less an hour after sunrise, along with visual performances, such as hanging in trees or leaves wiggle.

At present, Hylobates klossii is threatened throughout its native range, mainly as a result of habitat degradation, but also as a consequence of hunting and the pet trade.