Geographic Range
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.
- Other Geographic Terms
- island endemic
Habitat
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.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- forest
- rainforest
- mountains
- Aquatic Biomes
- coastal
- Wetlands
- swamp
Physical Description
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.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes colored or patterned differently
Reproduction
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.
- Mating System
- polygynous
- cooperative breeder
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.
- Key Reproductive Features
- iteroparous
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
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.
- Parental Investment
- precocial
- female parental care
-
pre-independence
-
provisioning
- female
-
provisioning
Lifespan/Longevity
The lifespan of
Trachypithecus auratus
is approximately 20 years, like many other species of Old World monkeys.
Behavior
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.
- Key Behaviors
- arboreal
- scansorial
- terricolous
- diurnal
- motile
- sedentary
- territorial
- social
- dominance hierarchies
Home Range
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.
Communication and Perception
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.
Food Habits
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.
- Animal Foods
- insects
- Plant Foods
- leaves
- seeds, grains, and nuts
- fruit
- flowers
Predation
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
).
Ecosystem Roles
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
.
- Ecosystem Impact
- disperses seeds
Economic Importance for Humans: Positive
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.
Economic Importance for Humans: Negative
There are no studies that document decreased health of people or agricultural plants
because of
Trachypithecus auratus
.
Conservation Status
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.
Other Comments
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.
Additional Links
Contributors
William Cannon (author), James Madison University, Abby Vos (author), James Madison University, Suzanne Baker (editor, instructor), James Madison University, Tanya Dewey (editor), Animal Diversity Web.
- oriental
-
found in the oriental region of the world. In other words, India and southeast Asia.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- island endemic
-
animals that live only on an island or set of islands.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- rainforest
-
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
- mountains
-
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- swamp
-
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- polygynous
-
having more than one female as a mate at one time
- cooperative breeder
-
helpers provide assistance in raising young that are not their own
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- young precocial
-
young are relatively well-developed when born
- female parental care
-
parental care is carried out by females
- arboreal
-
Referring to an animal that lives in trees; tree-climbing.
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- territorial
-
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
- social
-
associates with others of its species; forms social groups.
- dominance hierarchies
-
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- pet trade
-
the business of buying and selling animals for people to keep in their homes as pets.
- food
-
A substance that provides both nutrients and energy to a living thing.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
- frugivore
-
an animal that mainly eats fruit
References
Bristol Zoo Gardens, 2009. "Javan Langur" (On-line). Bristol Zoo Gardens. Accessed April 12, 2009 at http://www.bristolzoo.org.uk/learning/animals/mammals/langur .
Delson, E. 2008. "Monkey" (On-line). Mcgraw-Hill's Access Science: Encyclopedia of Science and Technology Online. Accessed April 12, 2009 at http://www.accessscience.com/content.aspx?id=432900#S2 .
Kool, K. 1991. Behavioural ecology of the silver leaf monkey, Trachypithecus auratus sondaicus, in the Pangandaran Nature Reserve, West Java, Indonesia. Primate Society of Great Britain , 44: 19-20.
Kool, K. 1993. The diet and feeding behavior of the silver leaf monkey (Trachypithecus auratus sondaicus) in Indonesia.. International Journal of Primatology , 14 (5): 667-700.
Nijman, V., . Supriatna. 2008. "Trachypithecus auratus" (On-line). 2008 IUCN Red List of Threatened Species. Accessed April 10, 2009 at http://www.iucnredlist.org/details/22034 .
Nijman, V. 2000. Geographic distribution of ebony leaf monkey Trachypithecus auratus (E. Geoffroy Saint-Hilaire, 1812) (Mammalia: Primates: Cercopithecidae). Contributions to Zoology , 69 (3): 157-177.
Primate Info Net, 2007. "Javan Langur (Trachypithecus auratus)" (On-line). Primate Fact Sheets. Accessed April 10, 2009 at http://www.theprimata.com/trachypithecus_auratus.html .
ProFauna Indonesia, 2008. "Javan Langur Conservation (JLC)" (On-line). ProFauna Indonesia. Accessed April 12, 2009 at http://www.profauna.org/content/en/javan_langur_conservation.html#information .
Richardson, M. 2005. "Javan langur (Trachypithecus auratus)" (On-line). Arkive: Images of Life on Earth. Accessed April 10, 2009 at http://www.arkive.org/javan-langur/trachypithecus-auratus/info.html .