Trachypithecus auratus
Javan langur

Trachypithecus auratus, commonly known as the Javan langur, is isolated to Java, Bali, and the Indonesian island of Lombok. They can be found in both the inland forests of western Indonesia as well as the southern coastline. (Nijman and Supriatna, 2008; Nijman, 2000; Richardson, 2005)

Trachypithecus auratus inhabits both the interior and edges of rainforests, and has been observed in both primary and secondary forests in the Dieng Mountains of central Java. Trachypithecus auratus has been observed in a variety of forest types: mangrove, beach, freshwater swamp, lowland and hill forest, deciduous forest, and mountain forest up to 3500 meters. (Primate Info Net, 2007; Nijman and Supriatna, 2008; Nijman, 2000; Richardson, 2005)

Two subspecies of Javan langurs are described: western Javan langur (or western Javan ebony langur (Trachypithecus auratus mauritius) and eastern Javan langurs (or spangled ebony langurs, Trachypithecus auratus auratus). However, several genetic studies dispute the validity of T. auratus subspecies. Both subspecies have glossy black coats with brown on the legs and belly. Sometimes, individual T. auratus auratus have orange coats. Orange color morphs are found in a restricted portion of the distribution of eastern Javan langurs. Javan langur infants are born with orange coats and the coats get darker as they age. Female coloration is slightly different, they have yellow pubic patches. Javan langur mass is approximately 7 kg. Head and body length is from 44 to 65 cm and tail length is 61 to 87 cm. They move quadrupedally and have enlarged salivary glands and a dental formula of 2:1:2:3. Javan langurs also have sacculated stomachs that assist in breaking down plant materials. (Kool, 1993; Nijman, 2000; Primate Info Net, 2007; Richardson, 2005)

Javan langurs have 1 to 2 males in each group, which has a large effect on the group's mating behavior. There is virtually no within-group competition among males, ensuring that they are successful in mating. Males in the group father all offspring. Females in social groups cooperate to care for all young in the group. (Bristol Zoo Gardens, 2009; Nijman, 2000; Primate Info Net, 2007)

Female Javan langurs typically begin to breed around 3 to 4 years of age, and give birth once a year, one offspring at a time. Breeding and births can occur throughout the year. The infants develop quickly and are often independent within their first year of life. Mothers in the group all care for each others' young, otherwise known as "allomothering." Other aspects of reproduction are not reported in the literature. (Bristol Zoo Gardens, 2009; Primate Info Net, 2007; Richardson, 2005)

Females are the primary caregivers for the infants and are known to care for infants from other females within the group. The vibrant color of young Javan langurs may make it easier for mothers to keep track of their offspring, and to ensure that they are protected and cared for. (Primate Info Net, 2007; Bristol Zoo Gardens, 2009; Richardson, 2005)

The lifespan of Trachypithecus auratus is approximately 20 years, like many other species of Old World monkeys. (Bristol Zoo Gardens, 2009; Delson, 2008)

Javan langurs are arboreal and diurnal, spending the majority of their time in trees and active during the day. Researchers found that when offered food from tourists, these langurs do not accept it. Individuals will often take turns and feed while others in the group are resting or traveling. They live in groups of approximately 7 members with 1 to 2 males and 5 to 6 females. However, groups can exist with up to 21 members, still with only 1 to 2 males. Group size varies depending on climate conditions. Groups inhabiting habitats with a longer dry season tend to be larger than other groups. Females make up the majority of the group because of male competition and the polygamous mating system. Males disperse from their natal group and may travel alone, or can band together with other bachelor males. The dominant male keeps a close relationship with all females within the group. Females care for and protect their young, as well as the offspring of their fellow female group members. Females are aggressive toward females from other groups. (Kool, 1991; Nijman and Supriatna, 2008; Nijman, 2000; Primate Info Net, 2007; Richardson, 2005)

Home range is estimated to be 20 to 30 ha. This home range may be larger in Java than on other Indonesian islands. Trachypithecus auratus has a population density of 23 individuals/km in the Dieng Mountains of Java. (Nijman and Supriatna, 2008)

Javan langurs communicate acoustically. They use alarm calls that sound like "ghek-ghok-ghek-ghok." They also communicate through visual cues and touch. Infants are brightly colored and females will look after and protect infants of other females. It has been hypothesized that females behave in this manner because the bright orange color of the infants signals that they need to be cared for. Allogrooming is an important way to cement social bonds. Aggression is communicated with physical interactions, vocalizations, and visual cues, all of which establish social rank. Research on chemical communication by Trachypithecus auratus has been lacking. (Primate Info Net, 2007; Richardson, 2005)

Javan langurs eat mostly leaves and flowers. Their enlarged salivary glands and sacculated stomachs are well adapted for this plant diet. They also eat fruit, ripe and unripe, and insect larvae. The diet consists of 15 to 27% unripe fruit and 10 to 12% ripe fruit. They may eat fruits mainly to get at the seeds. Javan langurs prefer leaves rich in protein content and low in fiber. Different groups will feed at the same food source without significant aggression. Adult males do not proportionally feed as often as other group members, females and the young. (Kool, 1993; Primate Info Net, 2007; Richardson, 2005)

The only known predators of Javan langurs are humans. Humans illegally hunt them for food and the pet trade. Anti-predator adaptations of T. auratus include a shrill alarm call when a human is sighted. Likely natural predators include the now extinct, Javan tiger (Panthera tigris sondaica) and Javan leopards (Panthera pardus melas). (Primate Info Net, 2007; Primate Info Net, 2007; Richardson, 2005)

Javan langurs impact forest vegetation through their diet, they eat leaves and may help to disperse seeds through their frugivory. No studies have been conducted on the parasites that infect Trachypithecus auratus. (Bristol Zoo Gardens, 2009; Kool, 1993; Nijman and Supriatna, 2008)

Javan langurs are important members of native ecosystems and may form the basis of ecotourism activities. Javan langurs are sometimes hunted for food or captured for trade, but these are illegal activities. (Primate Info Net, 2007; Nijman and Supriatna, 2008; Primate Info Net, 2007)

There are no studies that document decreased health of people or agricultural plants because of Trachypithecus auratus. (Nijman and Supriatna, 2008)

Javan langurs are listed as vulnerable on the IUCN Red List. Populations are decreasing due to human activities, such as habitat loss resulting from agricultural expansion, hunting, and the illegal pet trade. Laws protecting Trachypithecus auratus in Indonesia were passed in 1999. Javan langurs are found in 3 Indonesian national parks: Gunung Halimun, Pangandaran, and Ujung Kulon. (Nijman and Supriatna, 2008; Richardson, 2005)

Trachypithecus auratus has also been recognized by the following synonyms: Trachypithecus kohlbruggei (Sody, 1931), Trachypithecus maurus (Horsfield, 1823), Trachypithecus pyrrhus (Horsfield, 1823), Trachypithecus sondaicus (Robinson & Kloss, 1919), and Trachypithecus stresemanni Pocock, 1934. (Nijman and Supriatna, 2008)