Gray langurs are Old World monkeys native to the Indian subcontinent constituting the genus Semnopithecus. Traditionally only one species Semnopithecus entellus was recognized, but since about 2001, additional species have been recognized. The taxonomy has been in flux, but currently eight species are recognized.
The Mentawai Islands Regency are a regency of West Sumatra Province which consists of a chain of about a hundred islands and islets approximately 150 kilometres off the western coast of Sumatra in Indonesia. They cover a land area of 6,033.76 km2 and had a population of 76,173 at the 2010 Census and 87,623 at the 2020 Census; the official estimate as at mid 2022 was 89,401 - comprising 46,431 males and 42,970 females. Siberut at 3,838.25 square kilometres is the largest of the islands. The other major islands are Sipura, North Pagai, and South Pagai. The islands lie off the Sumatran coast, across the Mentawai Strait. The indigenous inhabitants of the islands are known as the Mentawai people. The Mentawai Islands have become a noted destination for surfing, with over 40 boats offering surf charters to international guests.
The Colobinae or leaf-eating monkeys are a subfamily of the Old World monkey family that includes 61 species in 11 genera, including the black-and-white colobus, the large-nosed proboscis monkey, and the gray langurs. Some classifications split the colobine monkeys into two tribes, while others split them into three groups. Both classifications put the three African genera Colobus, Piliocolobus, and Procolobus in one group; these genera are distinct in that they have stub thumbs. The various Asian genera are placed into another one or two groups. Analysis of mtDNA confirms the Asian species form two distinct groups, one of langurs and the other of the "odd-nosed" species, but are inconsistent as to the relationships of the gray langurs; some studies suggest that the gray langurs are not closely related to either of these groups, while others place them firmly within the langur group.
Kloss's gibbon, also known as the Mentawai gibbon, the bilou or dwarf siamang, is an endangered primate in the gibbon family, Hylobatidae. It is identifiable in that it is all black, resembling the siamang with its black fur, but is considerably smaller and lacks the siamang's distinctive throat pouch. Kloss's gibbon reaches a size 17 to 25 inches and weigh at most 13 pounds (6 kg). As is the case for all gibbons, they have long arms and no tail. Males and females are difficult to distinguish.
Siberut is the largest and northernmost of the Mentawai Islands, located 150 kilometres west of Sumatra in the Indian Ocean. It covers an area of 3,838.25 km2 including smaller offshore islands, and had a population of 35,091 at the 2010 Census and 40,220 at the 2020 Census. A part of Indonesia, the island is the most important home for the Mentawai people. The western half of the island was set aside as the Siberut National Park in 1993. Much of the island is covered with rainforest, but is subject to commercial logging.
The surilis are a group of Old World monkeys in the genus Presbytis. They live in the Thai-Malay Peninsula, on Sumatra, Borneo, Java and smaller nearby islands. Besides surili, the common names for the monkeys in the genus also often use the terms "langur" or "leaf monkey."
The pig-tailed langur, 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". It has been included on a list of the World's 25 Most Endangered Primates.
The Mentawai Islands rain forests is a tropical moist broadleaf forest ecoregion in Indonesia. It covers the Mentawai Islands, an archipelago in the Indian Ocean off the west coast of Sumatra. The islands have been separated from Sumatra since the mid-Pleistocene period, and their geographic isolation allowed the evolution of several endemic species, including 17 endemic mammals.
Siberut National Park comprises 1,905 km2 (47%) of the island of Siberut in the Mentawai Islands of West Sumatra, Indonesia. The whole island including the national park is part of the World Network of Biosphere Reserves.
The Pagai Island macaque, also known as the Pagai macaque or Bokkoi, is an Old World monkey 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. Macaca pagensis formerly included the overall darker Siberut macaque as a subspecies, but this arrangement is polyphyletic, leading to the two being classified as separate species. Both were formerly considered subspecies of the southern pig-tailed macaque.
The Cat Ba langur, also known as the golden-headed langur, is a critically endangered species of langur endemic to Cát Bà Island, Vietnam. It is among the rarest primates in the world, and possibly the rarest primate in Asia, with population size estimated at less than 70 individuals.
Phayre's leaf monkey, also known as Phayre's langur, is a species of Old World monkey native to South Asia and Southeast Asia, namely India, Bangladesh, and Myanmar. Populations from further east are now thought to belong to other species. It is listed as Endangered on the IUCN Red List and is threatened by hunting and loss of habitat. The species epithet commemorates Arthur Purves Phayre.
The Javan surili is a vulnerable species of Old World monkey endemic to the western half of Java, Indonesia, a biodiversity hotspot. Other common names by which it is known by include gray, grizzled or Sunda Island surili; grizzled or stripe-crested langur; Javan grizzled langur; grizzled, Java or Javan leaf monkey; langur gris.
The Raffles' banded langur, also known as the banded leaf monkey or banded surili, is a species of primate in the family Cercopithecidae. It is endemic to Singapore and southern Peninsular Malaysia. The species underwent taxonomic revisions in 2019 and 2020, in which two former subspecies were elevated to separate species. As a result, the Raffles' banded langur meets the criteria for being listed as critically endangered by the IUCN. It is mainly threatened by habitat loss.
The maroon langur, maroon leaf monkey, or red leaf monkey is a member of the family Cercopithecidae. It is found on the southeast Asian island of Borneo and the nearby smaller Karimata. P. rubicunda mostly live in forests at altitudes below 2,000 m. They feed on leaves, seeds, and fruits.
The dusky leaf monkey, also known as the spectacled langur, or the spectacled leaf monkey is a species of primate in the family Cercopithecidae. It is found in Peninsular Malaysia, Myanmar and Thailand, and can occasionally be found in Singapore. During the day, these small, folivorous primates divide in sub-groups and forage for vegetation and fruit throughout the tropical forests. According to the IUCN, the dusky leaf monkey's population is declining due to habitat loss, poaching, and anthropogenic land use, which prompted the IUCN to classify the species as endangered in 2015.
Germain's langur is a Old World monkey native to Thailand, Myanmar, Cambodia, Laos and Vietnam. The monkey was previously included in Trachypithecus cristatus and Trachypithecus villosus.
The mitered langur is a species of monkey in the family Cercopithecidae. It was formerly considered a subspecies of the Sumatran surili, Presbytis melalophos but genetic analysis revealed that these are separate species. The mitered langur is native to the island of Sumatra in Indonesia. It is listed as endangered by the IUCN due primarily to deforestation, and also due to animals taken for pets.
The Siberut langur is a species of monkey in the family Cercopithecidae. It was formerly considered a subspecies of the Mentawai langur, Presbytis potenziani but genetic analysis revealed that these are separate species. The Siberut langur is native to the island of Siberut in Indonesia. It is listed as endangered by the IUCN.
Miller's langur, also known as Miller's grizzled langur or Kutai grey langur, is a species of leaf monkey. It is endemic to East Kalimantan on the island of Borneo in Indonesia. It is one of the world's most endangered primates, and was at one time thought to be extinct, until it was rediscovered in 2012.
