The Mentawai langur (''Presbytis potenziani'') is a species of

primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...

in the family

Cercopithecidae Old World monkey is the common English name for a family of primates known taxonomically as the Cercopithecidae (). Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboons ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the

Mentawai Islands Mentawai may refer to: * Mentawai Islands * Mentawai Strait * Mentawai people * Mentawai language The Mentawai language is an Austronesian language, spoken by the Mentawai people of the Mentawai Islands, West Sumatra, Indonesia. Dialects Acco ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. Its natural habitat is subtropical or tropical dry forests. The Siberut langur (''P. siberu'') was formerly considered a subspecies of the Mentawai langur.

Description

Mentawai langur infants are born with a white pelage. After two to three weeks, the pelage begins to darken and the face becomes darkly pigmented. This change of coloration begins in the dorsal midline and head and ends laterally. After three months, the belly and chest are dark reddish-brown, throat, cheeks, forehead and tip of tail are white and the rest of the body is jet black. Males are differentiated from females by having a white circumgenital patch of fur. Mentawai langurs have a slender body with hind limbs longer than their forelimbs.

Distribution and habitat

Mentawai langurs are endemic to the islands of

Sipora Sipora (Indonesian: ''Sipora'' or sometimes spelled ''Sipura'') located off Sumatra in the West Sumatra Province of Indonesia, is the second-smallest and most developed of the four Mentawai Islands at only 651.55 km2. It had a population o ...

North Pagai North Pagai (Indonesian: ''Pagai Utara'') is the smallest of the four principal Mentawai Islands off the west coast of Sumatra in Indonesia. It is south of Sipora and north of South Pagai (or Pagai Selatan) Island. The population figure given f ...

, and

South Pagai South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþaz' ...

. They inhabit primary and secondary forests dominated by

dipterocarp Dipterocarpaceae is a family of 16 genera and about 695 known species of mainly tropical lowland rainforest trees. The family name, from the type genus ''Dipterocarpus'', is derived from Greek (''di'' = two, ''pteron'' = wing and ''karpos'' = fru ...

s. The trees used by ''Presbytis potenziani'' as sleeping areas are typically in height. The langurs sleep in the mid-upper levels of these trees above , where the canopy density is thickest, with the most common sites being in coconut groves.

Behavior and diet

On average, groups of Mentawai langurs travel each day. Heavy rainfall affects movement patterns light to moderate rainfall does not. The langurs move by quadrupedal running and climbing; they also leap in the mid and upper portions of the canopy and drop when nearer to the ground. Home ranges vary from . The groups are not migrants. Their social organisation is variable: unimale-unifemale, unimale-multifemale, multimale-multifemale. Mentawai langurs spend more than 80% of their time resting and foraging and only a small portion traveling and conducting social behavior. Such extensive periods of resting and foraging are required for colobines that consume seeds, unripe fruits and leaves to support their digestion. Adult males typically move away from the group in the early morning and give long calls. The langurs feed in the upper portion of the canopy. In some areas, their diet consists of 55% leaves, 32% fruit and seed and 13% other source of food such as flowers, bark, sap, and fungi. but groups that forage in secondary forests have a diet of 70% fruits and seeds and up to 35% "climber" type vegetation. The

niche breadth Niche may refer to: Science *Developmental niche, a concept for understanding the cultural context of child development *Ecological niche, a term describing the relational position of an organism's species *Niche differentiation, in ecology, the ...

of ''Presbytis potenziani'' is 0.22, based on Levin's index.

Conservation

The Mentawai langur is currently listed as critically endangered on the IUCN Red List. Over the 36 years prior to 2021, the population is estimated to have declined by 80%. The main threats to the monkeys are humans hunting for food and destruction of the habitat for agriculture. 25% of the hunting on Mentawai langur is by natives of central-south Siberut. Recommendations to conserve the species include development of a biosphere reserve on Siberut Island, creation of a primate reserve on South Pagai Island and offshore islands, a survey of primates on Sipora Island, a captive breeding program to recover the endemic subspecies of Mentawai primates on the southern islands, and beginning a campaign in education and law enforcement to prevent hunting of Mentawai langurs.

References

{{Taxonbar, from=Q631717 Presbytis Endemic fauna of Indonesia Mammals of Indonesia Mentawai Islands Regency Primates of Indonesia Endangered fauna of Asia Mammals described in 1856 Taxonomy articles created by Polbot Taxa named by Charles Lucien Bonaparte Wikipedia Student Program