SPANGLED EBONY LANGUR

Trachypithecus auratus

Geographic Distribution and Habitat
Spangled ebony langurs are Old World primates in the Colobine, or leaf-eating, family. They are endemic to isolated forest fragments of East Java, as well as the small islands of Bali, Lombok, Palau Sempu, and Nusa Barong. These volcanic islands are home to deciduous forests drenched by heavy downpours during the wet season, and refreshed by light rains during the dry season. Trees in these parts rarely exceed 80 feet (25 m) high and many belong to the Acacia and Cassia families.  

Palau Sampu Island is a Nature Reserve with coastal forest, mangroves, and lowland tropical forest. Nusa Barong, south of Java, boasts sandy beaches, a rainforest, and strikingly beautiful stone formations. It has been a nature reserve since 1920.

TAXONOMY IN TRANSITION

A 2008 phylogenetic study found that spangled ebony langurs and West Javan ebony langurs (Trachypithecus mauritius) were deserving of their own unique species designations, with the spangled ebony langur retaining the scientific name that they both shared, Trachypithecus auratus. This taxonomical change was announced by the International Union for Conservation of Nature (IUCN) in late 2020. Because the change was so recently widely adopted, a good deal of research still lumps West Javan ebony langurs and spangled ebony langurs together as one species. The two species are fairly similar in appearance, but are geographically and genetically separated. While these two species are closely related and share many of the same characteristics, they have unique characteristics as well, and we will undoubtedly discover more interesting traits that are unique to each as more research into each species is uncovered.

Spangled ebony langur range, IUCN 2021

Size, Weight, and Lifespan
Spangled ebony langurs have an average weight of 22 pounds (10 kg). Their body is approximately 21 inches (55 cm) and their tail 33 inches (85 cm) long. Males are somewhat larger than females.

It is estimated they can live up to 20 years.

Appearance
Spangled ebony langurs generally have glossy black coats with brownish tinges on their legs, sides, and sideburns. Like many langur species, infants are born with bright orange coats that darken to black as they age. Uniquely, some spangled ebony langur individuals carry a rare morph and they do not lose their juvenile coloring as they mature. Instead, their adult pelage remains golden, although slightly darker than that of infants, with yellow tinges on their sides, on their limbs, and around their ears, and with a black tinge on their backs. Their scientific name recognizes this morph in the word auratus, which means “gold” or “having the color of gold” in Latin. 

Spangled ebony langurs’ expressive faces are framed by unruly sideburns and heavy locks that fold down onto their forehead. Their brown eyes are accentuated by a strong eyebrow ridge. Their nose is flat and their nostrils look like two parentheses above a straight mouth. The pale wrinkled skin of their face gives them the appearance of old people, full of wisdom and knowledge.

Their limbs are long and lanky. Hands and feet have opposable thumbs and big toes. Their extremely long tails are nonprehensile.

What Does It Mean?

Endemic:
Native or restricted to a certain area or country.

Deciduous Forest:
Forests that change seasonally. The word deciduous means to fall off at maturity. The opposite of deciduous is evergreen.

Mangrove:
A mangrove refers to two different things: a tidal swamp ecosystem found in tropical deltas, estuaries, lagoons, or islands, and the characteristic tree species populating this ecosystem. Mangrove trees have developed unique adaptations to the harsh conditions of coastal environments. 

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. In zoology, a visual or behavioral difference between organisms of distinct populations in a species.

Sacculated:
Having a series of sack-like compartments.  

Anaerobic bacteria:
Bacteria that can live without oxygen.

Quadrupedal:
Using four limbs to move about. This word comes form the Latin meaning “four feet”.

Visit the Glossary for more definitions

Diet
Like all langurs, these primates feed almost exclusively on foliage. They prefer young leaves, which are rich in protein, to mature leaves. They also consume unripe fruit, some ripe fruit, flowers, buds, insects, and larvae.

Their large sacculated stomach is a evolutionary adaptation that allows them to feed from a wide variety of plants and trees, including those that may be toxic to other animals. This highly specialized digestive tract allows the langurs to absorb the nutrients they need while processing difficult-to-digest, high-cellulose leafy matter. Digestion begins with the aid of large salivary glands that contain specialized enzymes that begin the process of breaking down cellulose. Anaerobic bacteria ferment leaves and other ingested matter in the upper chamber of the stomach, then the cellulose breakdown completes in the lower chamber, which is more acidic. This digestive process demands a lot of energy. In addition, leafy matter that is high in cellulose is often low in nutrition. They have to dedicate a good portion of their day to foraging and resting during digestion, which explains why spangled ebony langurs are not as active as other primates during their waking hours.

Behavior and Lifestyle
Spangled ebony langurs are diurnal. They spend most of the day in trees, feeding and resting. Actually, they spend more than half of their day resting. They travel quadrupedally through the branches, from one feeding site to another and their home range usually covers approximately 50 to 75 acres (20–30 ha).

Daily Life and Group Dynamics
They live in groups, or “harems,” composed of one dominant male and several females, a number of immature males, juveniles, and infants of both genders. The group size varies and occasionally can include as many as 20–30 individuals.

Females are kin and remain within their natal group at maturity. This may explain their aggression towards females of other groups; even if, for the most part, inter-group encounters are rather peaceful.

Males, on the other hand, leave their natal group at age three, just shy of them becoming adults. Once they set out on their quest for independence, several young males may join together in a nomadic band and travel in search of breeding opportunities. These bands are aggressive and dangerous for established dominant males as they try to take over their females.

Fun Facts

In Hindi, the word “langur” means “long tail.” Locally, people call these langurs “lutung” or “budeng.”

The island of Java was formed by volcanic activity about 24 million years ago. It is the thirteenth largest island in the world.

Communication
Like all primates, Spangled ebony langurs use visual cues, touch, and vocalizations to communicate with one another. Facial expressions, body postures, and shaking of branches are all ways for them to convey emotions and messages.  

When they vocalize, they use several calls, each with specific meanings to alert the group of danger. They even use alarm calls for humans, whom they have learned to identify as predators.

Grooming is another communication tool used to cement bonds of friendship and keep the peace in the family. One or several langurs may groom each other at the same time.

Reproduction and Family
Females reach maturity at three or four years of age. There is no specific breeding season. The dominant male mates with multiple adult females. Mating occurs throughout the year.

After gestation, females give birth to a bright orange baby. They may share responsibilities for rearing the infants; “aunties” help the mother while she is feeding or otherwise occupied. The babies grow up quickly and they are able to feed themselves and travel independently after their first birthday.

Ecological Role
​Because they eat fruit, spangled ebony langurs can be considered seed dispersers. One could also argue that by eating foliage, they contribute to tree pruning and forest clearing. 

Conservation Status and Threats

Spangled ebony langurs are assessed as Vulnerable by the International Union for Conservation of Nature (IUCN, 2020), appearing on the IUCN’s Red List of Threatened Species. 

The spangled ebony langur’s population decline is largely caused by deforestation, hunting, and the illegal pet trade. Java is one of the most populated islands in the world, thus forests are cleared for human habitation and agriculture. Over 45% of the langurs’ habitat on Java Island has been destroyed. This is also the case on the surrounding islands. For instance, clearing of land to make room for tobacco, soy, coconut, and other crops has caused severe deforestation on the Lombok Island, despite the protected status of its rainforest and watershed.

Spangled ebony langurs are also illegally hunted for food and because some cultural beliefs associate their meat to exceptional cures for skin disease and other ailments. Finally, political instability and the inability to implement environmental laws, all too often ignored, are making conservation efforts difficult.

Except for humans, other natural predators, like Javan tigers, have disappeared.

Conservation Efforts
The species is listed on Appendix I of the Convention on International Trade in Endangered Species (CITES).  

Profauna—an Indonesian non-profit organization—founded the Javan Langur Center in 2003. The conservation program they initiated is now under the management of the Aspinal Foundation, Indonesia, in partnership with the Indonesian Ministry of Forestry. Together with local partners, the Aspinal Foundation works for the protection of various species, including Indonesian primates. They do so through research, species monitoring, habitat assessment, conservation, rehabilitation, captive breeding, and policy guidelines.

One of their programs started about ten years ago and aims at re-establishing a self-sustaining population of langurs in the Coban Talun Protected Forest, by releasing langurs from the Javan Langur Center and others from a captive breeding colony at Howletts and Port Lympne Wild Animal Parks in the UK. These two facilities participate in the European breeding program for spangled ebony langurs; their goal is to keep the gene pool diverse and healthy.

Profauna also played an important role in getting a protected status for the Javan langurs. Legal protection of the species seems to be bearing fruit. Recent surveys show that the number of langurs for sale on illegal markets is down compared to 25 years ago. A small victory, which unfortunately is shifting illegal activities toward less protected primates, like macaques.

References:​​

  • IUCN Red List
  • Reinforcing the isolated Javan langur population in the Coban Talun Protected Forest, East Java, Indonesia – Made Wedana, Iran Kurniawan, Zulfi Arsan, Novianto Bambang Wawandono, Amos Courage & Tony King.
  • www.apenheul.com/primates-abc/east-javan-langur 
  • www.wikipedia.org
  • The Jakarta Post – From animal hunter to animal rescuer – Duncan Graham (2017)
  • American Primatology Journal (2017) – Changes in the primate trade in Indonesian wildlife markets over a 25-year period: Fewer apes and langurs, more macaques and slow lorises – Vincent Nijman, Denise Spaan, Eva Johanna Rode-Margono, Wirdateti, KA I Nekaris.
  • www.profauna.net
  • www.animaldiversity.org
  • www.news.cgtn.com/news (December 2020) – Monkey Mania: The ebony langur that can also be golden orange
  • www.science.jrank.org – Langurs and Leaf Monkeys
  • www.worldwildife.org Indonesia: Island of Java

Written by Sylvie Abrams, June 2021