The pig-tailed langur (Simias concolor), monotypic in genus Simias, is a large Old World monkey, endemic to several small islands off the coast of Sumatra in Indonesia. Its face is black, its fur is black-brown and it has a relatively short tail. It is a diurnal species, feeding in the rainforest canopy on leaves, and to a lesser extent, fruit and berries. Little is known of its natural history, but it is heavily hunted, its populations have been declining rapidly and the International Union for Conservation of Nature has assessed its conservation status as being "critically endangered". Sexual swelling is exhibited by this species which is rare for single male multi female groups of Colobinae monkeys.
Classification
Many researchers would like to reclassify this species into the Nasalis genus but phylogenic analyses suggest that these two groups should remain in their separate sister taxa. The Critically Endangered status of this primate gives even more reason for it to remain under the genus Simias since the grouping of these genera could affect conservation efforts. Leaves are the most abundant in their diet followed by fruits. The second subspecies is Simias concolor siberut also known as simakobou which lives only on the island of Siberut. The activity budget of this primate is mostly resting and feeding with a small fraction of time devoted towards travel and social behavior. Other parts in Siberut show relatively high group sizes (mean group size 8.7). which include, destruction of forest for commercial use, hunting and illegal pet trade. In 2004 Lisa M. Paciulli dedicated their PhD dissertation towards studying threats to Mentawai island primates and determining population densities associated with logging pressures. Population estimates were found to be around 6,700-17,300 across all islands with a large amount of variation being attributed due to hunting and logging pressures. The second main factor associated with the population decline of this species is hunting. Local inhabitants have historically used arrows and poisonous materials to hunt this species.
- Pig-tailed langur, Simias concolor
- Simias concolor concolor
- Simias concolor siberu
Predation
The only known predator of pig-tailed langurs are humans. Other large predators on the Mentawai Islands include crested serpent eagles and reticulated pythons, both may also prey on pig-tailed langurs.