JAVAN LANGUR
Trachypithecus auratus
Geographic Distribution and Habitat
Javan langurs are Old World monkeys from the Colobinae subfamily. They live alongside many other primate species on the islands of Java, Bali, Palau Sempu, Nusa Barung, and Lombok, Indonesia. Some common names for this species are Javan langur, Javan lutung, ebony langur, and ebony leaf monkey, based on their characteristic long tails and dark coats.
There are two subspecies: the eastern Javan langur (Trachypithecus auratus, auratus), also called the spangled ebony lutung, and the western Javan langur (Trachypithecus auratus, mauritius).
Eastern Javan langurs have two morphs. The red morph is less common and found in a restricted area in south central Java. While all Javan langur babies are bright orange, this group continues to retain their orange coloring into adulthood.
Western Javan langurs reside near the capital of Jakarta and primarily south of there as well as to the western peninsula of the island.
Javan langurs thrive both at the peripheral and interior of many types of forests—mangrove, beach, lowland, hill, deciduous, freshwater swamp, and mountain forests. They inhabit areas that are at sea-level and up to elevations of 11,482 feet (3500 meters). Moving between the strata of the tropical forests in a temperate 72-84 degrees F (52-59 degrees C), their home territories can range from 49-74 acres (20-30 Hectares).
Javan langurs are Old World monkeys from the Colobinae subfamily. They live alongside many other primate species on the islands of Java, Bali, Palau Sempu, Nusa Barung, and Lombok, Indonesia. Some common names for this species are Javan langur, Javan lutung, ebony langur, and ebony leaf monkey, based on their characteristic long tails and dark coats.
There are two subspecies: the eastern Javan langur (Trachypithecus auratus, auratus), also called the spangled ebony lutung, and the western Javan langur (Trachypithecus auratus, mauritius).
Eastern Javan langurs have two morphs. The red morph is less common and found in a restricted area in south central Java. While all Javan langur babies are bright orange, this group continues to retain their orange coloring into adulthood.
Western Javan langurs reside near the capital of Jakarta and primarily south of there as well as to the western peninsula of the island.
Javan langurs thrive both at the peripheral and interior of many types of forests—mangrove, beach, lowland, hill, deciduous, freshwater swamp, and mountain forests. They inhabit areas that are at sea-level and up to elevations of 11,482 feet (3500 meters). Moving between the strata of the tropical forests in a temperate 72-84 degrees F (52-59 degrees C), their home territories can range from 49-74 acres (20-30 Hectares).
Javan langur geographic distribution. Map credit: Chermundy and IUCN
Size, Weight, and Lifespan The word “langur” means “long tail” in Hindi. Their tails certainly fit their name! When leaping from tree to tree, this primate’s tail waves approximately 2-3 feet (61 cm) behind. Males may have a tail reaching just over three feet (87 cm). Average body measurements are between 17-25 inches (44-65 cm) and average weight is 15-16 pounds (7-8 kg), with the males being slightly larger than the females. The life span of both species is approximately 20 years in the wild. Life in captivity has spanned up to 31 years. Appearance
This species has the defining characteristic of two distinct color coats. Adults are generally a glossy ebony while babies and juveniles have bright orange pelage. With age, the coat transforms from bright orange to a golden color in puberty and then to glossy black in adulthood. In western Java, black pelts are most common. Females can be distinguished by a lighter tuft of fur around the pubic area. The less common coloring is deep orange in color with yellow tinges on the side of the body, limbs and hair around the ears, and black tinges on the back. Their small heads (compared to their body size), with a lion-type mane, heart shaped face, and large almond shaped eyes, give these primates a unique look. Long arms, legs, fingers, and toes assist them in their movement through their dense jungle homes. Strong hand and foot grasps enable them to balance precariously on vines and small branches. Their long tails, straight when leaping from tree to tree, can be looped on branches for balance and additional support. |
What Does It Mean?Allomothering:
Females in a troop share responsibility for caring for the young. Individuals other than the biological mother of an offspring performs the functions of a mother (as by caring for an infant temporarily). Arboreal: Physically adapted to living primarily or exclusively in trees, such as arboreal-dwelling (tree-dwelling) monkeys. Diurnal: Active during daylight hours. Herbivorous: Anatomically and physiologically adapted for eating plant material, e.g. foliage, as the main component of ones diet. Marauding: To wander about and raid different places for food. Morph: A local population of a species that consists of interbreeding animals and is distinguishable from other populations by morphology or behavior though capable of interbreeding with them. Morphology: A branch of biology that deals with the form and structure of animals and plants. Sacculated: Having a series of different sections (langurs have three sections in their stomachs). |
Diet
Javan langurs are herbivorous primates. Their diet consists of young leaves, ripe fruit, unripe fruit, flowers, mature leaves, and a minimal amount of insect larvae. Choosing leaves with less fiber means they are better able to digest their food. Indeed, they have evolved a sacculated stomach with special bacteria in the first stomach to help break down this leafy diet. When food is scarce, they favor young leaves of the teak tree. They prefer the mid-rib, and will bend the leaf in half and chew out the center.
During the rainy season, when fruits can be found in abundance, they will consume even unripened fruit, primarily for the seeds. In this way, Javan langurs play an important role in the food chain, eating fruit and dispersing seeds in their excrement to repopulate the forest.
Much of the water consumed is absorbed from their food or from the dew and rain on the leaves in this lush, tropical climate. They rarely leave the canopy as a result.
These herbivorous monkeys, due to their simple diet of leaves and fruit, do not obtain many nutrients. This lack of nutrients gives them a lower energy level than many of the other Old World Monkeys.
Javan langurs are herbivorous primates. Their diet consists of young leaves, ripe fruit, unripe fruit, flowers, mature leaves, and a minimal amount of insect larvae. Choosing leaves with less fiber means they are better able to digest their food. Indeed, they have evolved a sacculated stomach with special bacteria in the first stomach to help break down this leafy diet. When food is scarce, they favor young leaves of the teak tree. They prefer the mid-rib, and will bend the leaf in half and chew out the center.
During the rainy season, when fruits can be found in abundance, they will consume even unripened fruit, primarily for the seeds. In this way, Javan langurs play an important role in the food chain, eating fruit and dispersing seeds in their excrement to repopulate the forest.
Much of the water consumed is absorbed from their food or from the dew and rain on the leaves in this lush, tropical climate. They rarely leave the canopy as a result.
These herbivorous monkeys, due to their simple diet of leaves and fruit, do not obtain many nutrients. This lack of nutrients gives them a lower energy level than many of the other Old World Monkeys.
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Behavior and Lifestyle
Javan langurs are diurnal and arboreal. The troop spends the night in the canopy. There is almost no competition within the group, but when threatened from without the group, the male leader shouts a warning and stays to defend the group as the family retreats into the jungle. Daily Life and Group Dynamics
They live in social groups of 6-23 members with one or two males to multiple females. Climate conditions and food availability determines the size of the group. During a long dry season, groups often grow in size. Males will leave the group at puberty and live alone or with other males. The dominant male of a group mates with all females of the group. Females can be aggressive to adult females from other groups. All females in one family group tend to the infants in their group, even infants from other mothers (allomothering). Babies are bright orange and some researchers believe this helps the troop keep track of their young and remember to meet their needs. As langurs groom one another and care for the young, the members of the group are assured of their acceptance, and even their survival. |
Fun FactsJavan langurs have enlarged salivary glands to assist in breaking down food in their mouth. When offered food from tourists, these langurs do not take it! One method of keeping marauding primates out of farmer's fields is to install a bazooka-like tool that makes a loud explosive sound to frighten the monkeys away. |
Communication
Like other primates, the ebony leaf monkey communicates their status with visual cues, touch, and grooming. These behaviors signal social acceptance to members of the group. When danger is perceived, they will raise an alarm with a vocalized “ghek ghok, ghek ghok.” As they spend their days foraging in the dense jungle, this vocal communication is essential. Some vocalizations signal a source of food so that others can join them in the feast.
Both males and females will communicate aggression with bared teeth, loud noises, and possibly physical attacks in order to establish social hierarchy. However, generally, females in one group are only aggressive to females outside their family group.
Like other primates, the ebony leaf monkey communicates their status with visual cues, touch, and grooming. These behaviors signal social acceptance to members of the group. When danger is perceived, they will raise an alarm with a vocalized “ghek ghok, ghek ghok.” As they spend their days foraging in the dense jungle, this vocal communication is essential. Some vocalizations signal a source of food so that others can join them in the feast.
Both males and females will communicate aggression with bared teeth, loud noises, and possibly physical attacks in order to establish social hierarchy. However, generally, females in one group are only aggressive to females outside their family group.
Reproduction and Family
Mating occurs all year. Females are ready to breed between the ages of three and four. Males mature at four to fives years of age.
Pregnant females will gestate for 7 months and produce one offspring at a time. The babies grow to be independent usually in their first year.
Mating occurs all year. Females are ready to breed between the ages of three and four. Males mature at four to fives years of age.
Pregnant females will gestate for 7 months and produce one offspring at a time. The babies grow to be independent usually in their first year.
Photo credit: Fred Hsu/Creative Commons
Ecological Role
Javan langurs are important forest cultivators. Their frugivorous diet and dispersal of seeds through their feces helps to replenish their habitat. In this way, they are vital to the health of the ecosystem and tropical biodiversity.
Javan langurs are important forest cultivators. Their frugivorous diet and dispersal of seeds through their feces helps to replenish their habitat. In this way, they are vital to the health of the ecosystem and tropical biodiversity.
Conservation Status and Threats
The javan langur is listed as Vulnerable by the International Union for Conservation of Nature (IUCN, 2008). Total populations have declined by 30% over the last 36 years (three generations of langurs).
A chain of volcanic mountains runs the length of Java, which creates a rich environment for the Javan langur, but has the effect of fragmenting the langur’s populations. Increased urban incursion into the wilderness separates the groups even further. Java is the thirteenth largest island in the world, yet has the world’s largest island human population. The growth of the human population puts severe pressure on the wildlife of the islands.
Destruction of the Javan langur’s habitat is occuring at an alarming rate. As cities grow, timber is extracted from the jungle without being replenished. Farmers set fire to the jungles in order to clear more land for agriculture. As agriculture spreads into former jungle areas, many monkeys raid the crops creating an ongoing conflict with human primates.
Past natural predators, the Javan leopard and Javan tiger, are extinct or near to extinction. Now, the only predators of the Javan langur are human primates. Langurs are often poached for the illegal pet trade or for commercial and food purposes.
The javan langur is listed as Vulnerable by the International Union for Conservation of Nature (IUCN, 2008). Total populations have declined by 30% over the last 36 years (three generations of langurs).
A chain of volcanic mountains runs the length of Java, which creates a rich environment for the Javan langur, but has the effect of fragmenting the langur’s populations. Increased urban incursion into the wilderness separates the groups even further. Java is the thirteenth largest island in the world, yet has the world’s largest island human population. The growth of the human population puts severe pressure on the wildlife of the islands.
Destruction of the Javan langur’s habitat is occuring at an alarming rate. As cities grow, timber is extracted from the jungle without being replenished. Farmers set fire to the jungles in order to clear more land for agriculture. As agriculture spreads into former jungle areas, many monkeys raid the crops creating an ongoing conflict with human primates.
Past natural predators, the Javan leopard and Javan tiger, are extinct or near to extinction. Now, the only predators of the Javan langur are human primates. Langurs are often poached for the illegal pet trade or for commercial and food purposes.
Conservation Efforts
Javan langurs are listed in Appendix II of the Convention on International Trade in Endangered Species (CITES). This assures that any legal international trade of these primates will be highly monitored.
Protected by Indonesian Law since 1999, their status in 2005 was improved further by making hunting and poaching of Javan langurs a punishable offense or 5-8 years in prison and 50 million rupiah fines.
Several national parks in west, southern, and central Java provide a protected habitat for the Javan langur:
In 1994, Profauna Indonesia, a non-governmental organization (NGO), was established to provide educational support for the preservation of wildlife.
Profauna works toward forest and wildlife protection on Java. Visit http://www.profauna.net/en/primate-campaign to follow the latest news from the largest grassroots organization in Indonesia working to protect the Javan Langur. Part of their work helps to find solutions and educate farmers concerning conflicts with crop-raiding langurs. Every year, more communities participate in Indonesian Primate Day, a nationwide effort to raise awareness of the plight of the Javan langur and other primates.
The Aspinal Foundation works with the government to rescue pet langurs, and rehabilitate and reintroduce them back into the national parks of Indonesia.
Without continued efforts, the population of Javan langurs will continue its downward spiral. The jungles of these tropical islands will suffer from the loss of these primates due to the important role they fill in forest cultivation.
Javan langurs are listed in Appendix II of the Convention on International Trade in Endangered Species (CITES). This assures that any legal international trade of these primates will be highly monitored.
Protected by Indonesian Law since 1999, their status in 2005 was improved further by making hunting and poaching of Javan langurs a punishable offense or 5-8 years in prison and 50 million rupiah fines.
Several national parks in west, southern, and central Java provide a protected habitat for the Javan langur:
- Gunung Halimun National Park, south of Jakarta
- Ujung Kulon National Park, the western peninsula of Java
- Pangandaran National Park, south central Java
In 1994, Profauna Indonesia, a non-governmental organization (NGO), was established to provide educational support for the preservation of wildlife.
Profauna works toward forest and wildlife protection on Java. Visit http://www.profauna.net/en/primate-campaign to follow the latest news from the largest grassroots organization in Indonesia working to protect the Javan Langur. Part of their work helps to find solutions and educate farmers concerning conflicts with crop-raiding langurs. Every year, more communities participate in Indonesian Primate Day, a nationwide effort to raise awareness of the plight of the Javan langur and other primates.
The Aspinal Foundation works with the government to rescue pet langurs, and rehabilitate and reintroduce them back into the national parks of Indonesia.
Without continued efforts, the population of Javan langurs will continue its downward spiral. The jungles of these tropical islands will suffer from the loss of these primates due to the important role they fill in forest cultivation.
References:
- http://animaldiversity.org/accounts/Trachypithecus_auratus/
- http://www.arkive.org/javan-langur/trachypithecus-auratus/image-G123911.html
- http://www.theprimata.com/trachypithecus_auratus.html
- https://www.profauna.net/en
- https://www.youtube.com/watch?v=Rbj2quhDC64
- https://wildanimalworlds.wordpress.com/2015/08/18/ebony-leaf-monkey-trachypithecus-auratus/
- https://www.cites.org/
- http://www.iucnredlist.org/details/22034/0
- https://www.aspinallfoundation.org/port-lympne/wildlife-park/animals/javan-langur/
Written by Carolyn North, February 2018
