logging and conversions to commercial palm oil plantations through concessions and illegal activities. Many of the areas in the southern Mentawai islands have experienced heavy logging operations that have left little forestry for the Mentawai primates. Most of the forestry has now been reduced from primary forestry to secondary forestry which is troubling since the pig-tailed langur thrives in arboreal environments. The reduction on forestry in the southern Mentawai islands creates a domino effect of paving new land for more human activities and settlement. 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. However technological advancements of firearms have facilitated the hunting of this species, especially since it is one of the largest primates on these islands. Many local inhabitants hunt this species because it is considered a delicacy, with many locals saying it has the best tasting meat compared to other primates. Population density data suggests that an increase in hunting pressure at survey sites results in lower population densities of this primate. Subspecies Genus Simias Pig-tailed langur, Simias concolor Simias concolor concolor Simias concolor siberu References Colobinae Endemic fauna of Indonesia Fauna of Sumatra Mammals of Indonesia langur Critically endangered biota of Asia Mammals described in 1903 Species endangered by habitat loss Species endangered by use as food Species endangered by the pet trade Taxa named by Gerrit Smith Miller Jr. Critically endangered fauna of Indonesia