Simias concolor, Pig-tailed Langur

Simias concolor

Pig-tailed Langur

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The Pig-tailed Langur (Simias concolor, monotypic in genus Simias) is a large, rather heavily built Old World monkey, which is adapted to climbing with its long arms. Its fur is black-brown, and its hairless face is also black. It is the only monkey in the subfamily Colobinae to have a relatively short tail; the tail is only slightly furred and is only 15 cm long. The short nose is pointed upward. The Pig-tailed Langur reaches a full grown length of approximately 50 cm and a weight of 7 kg. Traditionally, it has been placed in the genus Nasalis together with the Proboscis Monkey – a treatment still preferred by some.

This primate lives only on the Mentawai Islands, where it is known as Simakobou in Siberut and Simasepsep on the southern islands of Sipura, North Pagai, and South Pagai. Two of these islands, North- and South-Pagai, are its main range. It is a diurnal and arboreal rain forest dweller, rarely coming to the ground. It lives in small groups (3 to 8 animals), which consist of a male, one or more females, and their offspring. Its diet consists mainly of leaves and, to a lesser extent, fruits and berries. Nothing of its reproduction is known.

Trachypithecus-auratus, Javan Lutung, Lutung budeng


Javan Lutung, Lutung budeng

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The JavaTrachypithecus-auratus, Javan Lutung, Lutung budengn Lutung, Trachypithecus auratus[1] also known as the Ebony Lutung and Javan Langur, is an Old World monkey from the Colobinae subfamily. It is most commonly glossy black with a brownish tinge to its legs, sides, and “sideburns”.It is found on and endemic to the island of Java, as well as on several of the surrounding Indonesian islands. The Latin word auratus in its scientific name means “golden”, and refers to a less common color variant. Note that the common name Golden Langur is used for a different species.

Like all langurs, this species’ tail is noticeably long, measuring up to 87 cm in length while the body is only around 55 cm long. The two subspecies of this lutung are fairly similar in appearance and are geographically separated; males and females are both usually glossy black, although the females pale, yellowish white patch around the pubic area. Juveniles of both subspecies are orange in color. The nominate subspecies Trachypithecus auratus auratus has a rare race that does not lose its juvenile coloration when it matures, instead the coloration darkens slightly, with yellow tinges on its sides, limbs, and around its ears, and a black tinge on its back.

The Javan Lutung inhabits the interior and peripheral areas of rainforests.

This primate is diurnal and arboreal. Its diet is primarily herbivorous, eating leaves, fruit, flowers, and flower buds, although it also eats insect larvae. As with other colobines, it has evolved a specialised stomach to digest plant material more efficiently.This species also has enlarged salivary glands to assist it in breaking down food.

Like other langurs, the Javan Lutung is a social animal, living in groups of around seven individuals, with one or two adult males in the group. Although they will look after offspring of other mothers as well as their own, adult females are aggressive towards females from other groups. The brighter coloring of juveniles may alert females to their presence and ensures that they will always be noticed and protected. This species has no discernible mating season and females produce one offspring at a time.


* Spangled Ebony or Eastern Javan Lutung, Trachypithecus auratus auratus
* Western Javan Lutung, Trachypithecus auratus mauritius

Trachypithecus-cristatus, Silvery Lutung


Silvery Lutung


The Silvery Lutung (TrachypithTrachypithecus-cristatus, Silvery Lutungecus cristatus), also known as the Silvered Leaf Monkey or the Silvery Langur, is an Old World monkey with grey tips on dark brown or black fur, although the groin and ventral side of the tail are yellowish in color. Females range from 46-51cm with an average weight of 5.7kg and a tail length of 67-75cm. Males are 50-58cm with an average weight of 6.6kg and a tail length of 67-75cm. When born this monkey is orange, developing its adult coats around three months. It has a highly complex, large stomach to digest the cellulose found in its herbivorous diet. This species is the type of its species group.

The Silvered Leaf Monkey is arboreal, living in coastal, mangrove, and riverine forests from Burma to Indochina and Borneo. Groups range from 9-30 individuals with one adult male and many adult females communally caring for infants. The adult male protects his group and territory from competing males, communicating his dominance to other males via vocalizations and fighting. it is thought that this creature has orange nostrils and is a distant descendant from a dragon. these are old irish tales and were created around the 17th century when this animal inhabited the scottish Loch Ness.


* Trachypithecus cristatus cristatus
* Trachypithecus cristatus vigilans

Hylobates klossii, Kloss’ gibbon

Hylobates klossii

Kloss’ gibbon


Kloss’s Hylobates klossii, Kloss' gibbon Gibbon (Hylobates klossii), also known as the Mentawai Gibbon or the Bilou, is a primate in the Hylobatidae or gibbon family. It resembles the Siamang with its black fur, but is considerably smaller and lacks the Siamang’s distinctive throat pouch. Kloss’s Gibbon reaches a size 44 to 63 cm and weigh at most 6 kg. As is the case for all gibbons, they have long arms and no tail.

Kloss’s Gibbon exclusively lives on the Mentawai Islands that lie to the west of Sumatra. It is a diurnal inhabitant of the rain forest that hangs in the trees from its long arms and rarely comes to the ground. Like all species of gibbons it lives together in pairs that stake out a territory from approximately 20 to 30 hectares of size. This area is defended vehemently against other gibbons. Its diet consists mainly of fruits, occasionally also eating different plant parts, bird eggs, insects and small vertebrates.

The singing of Kloss’s Gibbon is considered the most beautiful of all the gibbons’ songs. Males and females will sing at considerable length either singlely or in duets, particularly during the morning and evening. The singing of the gibbons serves to warn off other animals from their territory, and possibly to strengthen the family bonds.

The reproductive cycle of Kloss’s Gibbon is similar to that of other gibbons. Every two to three years the female may give birth to a single young (with a gestation period of seven months). The young is weaned in the middle of its second year, and is fully mature in about seven years. Their life expectancy is about 25 years in the wild, and up to 40 years in captivity.

Hylobates lar, Lar Gibbon , Owa Sarudung

Hylobates lar

 Lar Gibbon , Owa Sarudung

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The LaHylobates lar, Lar Gibbon , Owa Sarudung r Gibbon (Hylobates lar), also known as the White-handed Gibbon, is a primate in the Hylobatidae or gibbon family. It is one of the more well-known gibbons and is often seen in zoos.

The range of the Lar Gibbon historically extended from southwest China and eastern Myanmar to Thailand and Burma down the whole Malay Peninsula in primary and secondary tropical rain forests. It is also present in the northwest portion of the island of Sumatra. In recent decades, especially the continental range has been reduced and fragmented, and the animals are thought to be extinct in China.The gibbon genus is highly allopatric, usually separated by large rivers. The Lar Gibbon shares its range with only the siamang, Symphalanges syndactylus, on the tip of the Malaysian peninsula and Sumatra.


The fur coloring of the Lar Gibbon varies from black and dark-brown to light brown sandy colors. The hands and feet are white colored, likewise a ring of white hair surrounds the black face. Both males and females can be all color variants, and the sexes also hardly differ in size. Gibbons are true brachiators, propelling themselves through the forest by swinging under the branches by their arms. Reflecting this mode of locomotion, the white-handed gibbon has curved fingers, elongated hands, extremely long arms and relatively short legs, giving it an intermembral index of 129.7, one of the highest of the primates. As with all apes, the number of caudal vertebrae have been reduced drastically, resulting in the loss of a functional tail.

Diet and Dentition

The Lar Gibbon is considered frugivorous with fruit constituting 50% of its diet, but leaves (29%) are a substantial part, with insects (13%) and flowers (9%) forming the remainder Its dental formula is, the generalized formula for Old World monkeys and apes. The dental arcade is U-shaped, and the mandible is thin and light. The incisors are broad and flat, while the molars have low, rounded cusps with thick enamel. The most noticeable characteristic of the dentition of Hylobates lar is the presence of large, dagger-like canines in both the upper and lower jaw. These canines are not sexually dimorphic.


Lar Gibbons are diurnal and arboreal, inhabiting rain forests. They rarely come to the ground, instead using their long arms to brachiate through the trees. With their hooked hands they can move swiftly with great momentum, swinging from the branches. Its social organization is dominated by monogamous family pairs, with one breeding male and one female along with their offspring. When a juvenile reaches sexual maturity, it is expelled from the family unit. However, this traditional conception has come under scrutiny. Long-term studies conducted in Khao Yai National Park in Thailand suggest that their mating system is somewhat flexible, incorporating extra-pair copulations, partner changes and polyandrous groupings.
Family groups inhabit a firm territory, which they protect by warding off other gibbons with their calls. Each morning the family gathers on the edge of its territory and begins a “great call,” a duet between the breeding pair. Each species has a typified call and each breeding pair has unique variations on that theme. The great call of Hylobates lar is characterized be its frequent use of short hoots with more complex hoots, along with a “quavering” opening and closing. These calls are one of the traits used determining species differences among the gibbons.


Sexually they are similar to other gibbons. Gestation is seven months long and pregnancies are usually of a single young. Young are nursed for approximately two years, and full maturity comes at about 8 years. The life expectancy of the Lar Gibbons in the wild is about 25 years.


Lar Gibbons are threatened in various ways: they are sometimes hunted for their meat, sometimes a parent is killed in order to capture young animals for pets. The largest danger, however, is the loss of habitat. With breathtaking speed the forests of Southeast Asia are cut down in order to establish plantations, fields and settlements. National parks and protected areas exist, but are often poorly supervised.


There are five subspecies of Lar Gibbon:
* Malaysian Lar Gibbon, Hylobates lar lar
* Carpenter’s Lar Gibbon, Hylobates lar carpenteri
* Central Lar Gibbon, Hylobates lar entelloides
* Sumatran Lar Gibbon, Hylobates lar vestitus
* Yunnan Lar Gibbon, Hylobates lar yunnanensis (possibly extinct

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Hylobates-agilis, Agile Gibbon, Ungko


 Agile Gibbon, Ungko

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The  Hylobates-agilis, Agile Gibbon, UngkoAgile Gibbon (Hylobates agilis), also known as the Black-handed Gibbon, is a primate in the Hylobatidae or gibbon family. The fur coloring of these animals can vary from black to red-brown. Their brows are always white, however, and males can be recognized by their white or light-grey cheeks. Additionally, males are slightly larger than females. Agile Gibbons reach an average weight of 5.5 kg and a length of 40 to 60 cm. Like all gibbons they are tailless.

The range of the Agile Gibbon is Southeast Asia, primarily the island Sumatra (but not the north part of the island), the southwest of the island of Borneo as well as a small area on the Malay Peninsula. With their long arms they swing by the branches, brachiating at a fast pace. They predominantly live arboreally in rain forests and rarely come to the ground. Like all gibbons, they live in serially monogamous pairs in a strictly enforced territory, which they defend with vigorous visual displays and songs. The diet of the Agile Gibbon consists mainly of fruits, leaves and insects.

Gestation time is seven months and births are of a single offspring. Young are weaned at barely 2 years of age. Once they are fully mature (at about 8 years), it leaves its family group in order to look for a mate.

There are three subspecies of the Agile Gibbon:

* Mountain Agile Gibbon, Hylobates agilis agilis
* Bornean White-bearded Gibbon, Hylobates agilis albibarbis
* Lowland Agile Gibbon, Hylobates agilis unko

Some scientists list the Bornean White-bearded Gibbon as its own species in full.

Hylobates-moloch, Silvery Gibbon


 Silvery Gibbon

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The SilveHylobates-moloch, Silvery Gibbonry Gibbon (Hylobates moloch) is a primate in the Hylobatidae or gibbon family. Their skin is bluish grey in colour, with a dark grey or black cap. Like all gibbons, they have no tail and their arms are long compared to their body. On average, they reach 8 kg in weight.

The Silvery Gibbon lives exclusively on the island of Java (Indonesia), where it inhabits deeply hidden portions of the rain forests. It is diurnal and arboreal, climbing trees skillfully and brachiating through the forests. Its diet consists of fruits, leaves, and flowers.

Every three years, on average, the female births a single young, after a seven month gestation. The offspring is nursed for about 18 months and lives with the family group until it is fully mature at about 8 years.

The Silvery Gibbon ranks among the most threatened primates. It is listed as Endangered on the 2009 IUCN Red List of Threatened Species, there is a 50% chance of the Silvery Gibbon becoming extinct within the next decade. Habitat destruction on densely populated Java continues to reduce the natural range of the species. Many gibbons are also lost to the illegal pet trade, when adult gibbons are slaughtered so that their babies can be sold in the markets as pets. There are less than 2000 Silvery Gibbons in the wild considered to be genetically viable for the continuation of the species. There are also a dozen small non-viable populations. Aside from these wild populations many Silvery Gibbons are held as pets throughout Indonesia.

Several zoos operate Silvery Gibbon breeding programs. Despite these efforts, the future survival of this species is in question.

Like all gibbon species, the Silvery Gibbon lives in pairs and stakes out territory that the pair strongly defends; it has relatively small territories of about 42 acres (17 ha). Females sing to declare their territory several times a day, and if strangers are spotted the male screams loudly in an attempt to scare them away.

There are two subspecies of the Silvery Gibbon:

* Western Silvery Gibbon or Western Javan Gibbon, Hylobates moloch moloch
* Eastern Silvery Gibbon or Central Javan Gibbon, Hylobates moloch pongoalsoni

Hylobates-muellerii, Gray Gibbon, Klampiau


 Gray Gibbon, Klampiau

The genus HylobatHylobates-muellerii, M�s Gray Gibbon, Klampiaues is one of the four genera of gibbons. It was once considered the only genus, but recently its subgenera (Hoolock [formerly Bunopithecus], Nomascus, and Symphalangus) have been elevated to the genus level.Hylobates remains the most speciose and widespread of gibbon genera, ranging from southern China (Yunnan) to western and central Java. Individuals within this genus are characterized by 44 chromosomes and often have a ring of white fur around their faces.

Hylobates-syndactylus, Siamang, Siamang


 Siamang, Siamang

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The Siamang (Symphalangus syndactylus) is a tailless, arboreal, black furred gibbon native to the forests of Malaysia, Thailand, and Sumatra. The largest of the lesser apes, the Siamang can be twice the size of other gibbons, reaching 1 m in height, and weighing up to 14 kg. The Siamang is the only species in the genus Symphalangus.

The Siamang is distinctive for two reasons. The first is that two fingers on each hand are fused together — hence the name “syndactylus”, from the Ancient Greek sun-, “united” + daktulos “finger”. The second is the large “gular sac” (found in both male and female of the species), which is a throat pouch that can be inflated to the size of its head, allowing the Siamang to make loud resonating calls or songs.

There may be two subspecies of the Siamang. If so, they are the nominate Sumatran Siamang (S. s. syndactylus) and the Malaysian Siamang (S. s. continentis, in peninsular Malaysia).[3] Otherwise, the Malaysian individuals are only a population. The Siamang is the only gibbon which occurs sympatrically with other gibbons; its two ranges are entirely within the combined ranges of the Agile Gibbon and the Lar Gibbon. Although the siamang is given a different name than other gibbons, this division is not cladistically sound, since the genus Nomascus split from the rest of the gibbons before Symphalangus split [4]

The Siamang can live up to 30+ years in captivity.

While the illegal pet trade takes a toll on wild populations, the principal threat to the Siamang is habitat loss in both Malaysia and Sumatra. Palm oil production is clearing large swathes of forest, reducing the habitat of the Siamang, along with that of other species such as the Sumatran Tiger.

The Siamang inhabits the forest remnants of Sumatra Island and the Malay Peninsula, and is widely distributed from lowland forest to montane forest, even a rainforest. And can be found at altitudes of up to 3800 m . The Siamang lives in groups of up to 6 individuals (4 individuals on average) with a home range 23 hectares on average. Their day ranges are substantially smaller than those of sympatric Hylobates species, often less than 1 km. The Siamang’s melodious choir singing breaks the forest’s silence in the early morning after the Agile Gibbon or Lar Gibbon’s calls. The Siamang in Sumatra and the Malay Peninsula are similar in appearance, but there are some differences in behaviour between the two populations.


The Siamang mainly eats various parts of plants. The Sumatran Siamang is more frugivorous than its Malayan cousin, with fruit making up to 60% of its diet. The Siamang eats at least 160 species of plants, from vines to woody plants. Its major food is figs (Ficus spp.), a member of Moraceae family.The Siamang prefers to eat ripe fruit rather than unripe fruit, and young leaves rather than old leaves. It eats flowers and a few animals, mostly insects. When the Siamang eats large flowers, it will eat only the corolla (petal), but it will eat all parts of smaller flowers, with the small fruit collected in its hand before being consumed. When it eats big and hard seeds or seeds with sharp edge it will peel out the fruit flesh and throw away the seed.
Although its diet consists of substantial portions of fruit, it is the most folivorous of all members of Hylobatidae. As it is also the largest gibbon, and thus fits well with the general primate dietary trend in which larger primates tend to be more folivorous

Demography and population

A group of Siamang normally consist of an adult dominant male, an adult dominant female, with offspring, infant and sometimes a sub-adult. The sub-adult usually leaves the group after the age 6 to 8 years; sub-adult females tend to leave the group earlier than sub-adult males. Siamang males tend to offer more paternal care than other members of the family Hylobatidae, taking up a major role in carrying the infant after it is about 8 months old . The infant typically returns to its mother to sleep and nurse. A study in relation to effect of habitat disturbance on the Siamang found that group composition is varied in age-sex structure between intact forest and post-burnt forest. The post-burnt population was more adult and sub-adults than the intact population. Post-burnt groups contain fewer infants, small juveniles and large juveniles compared to intact forest groups. Infant survival rates in post-burnt groups are lower than in intact forests. The number of individuals in intact forests is higher than in post-burnt forests.The Siamang in disturbed forests live in small groups and have a density lower than in intact forests because of lack of food resources and trees for living.

In the 1980s, the Indonesian population of the Siamang in the wild was estimated to be 360,000 individuals.
This seems over-estimate today, as an example, Bukit Barisan Selatan National Park (BBSNP) is the third largest protected area (3,568 km²) in Sumatra, of which approximately 2,570 km² remains under forest cover inhabit by 22,390 siamangs (in 2002 censuses). According to two different research projects conducted in Sumatra, the Siamang prefer to inhabit lowland forest below between 500 m in altitude and over 1000 m above sea level.


The Siamang tends to rest for more than 50% of its waking period (from dawn to dusk), followed by feeding, moving, foraging and social activities. It takes more rest during midday, taking time to groom each other or play. During resting time it usually uses a branch of a large tree lying on their back or on their stomach. Feeding behaviors, foraging, and moving are most often in the morning and after resting time.

In the dry season the length of the Siamang’s daily range is longer than in the rainy season. The Siamang in southern Sumatra undertakes less foraging than the Siamang in other places because it eats more fruit and therefore consumes more nutrition, which results in less time needed for looking for food. Sometimes the Siamang will spend all of the day in one big fruiting tree, just moving out when it wants to rest and then coming back again to fruiting trees.

Role of calling

The Siamang starts its day by calling in the early morning and calls less after midday, with the peak of their calls around 9:00 am to 10:00 am. Most of the Siamang’s calls are directed to its neighbours rather than to inside its home range. This means that the Siamang’s calling is in response to disturbances and is to defend its territory. Calls in the late morning typically happen when it meets or sees another Siamang group. The edge of the Siamang’s home range, which may overlap another, is often the places where calling is made. Counter-call (co-response calling) occasionally happens near the border or in the overlap area. Calls are numerous when fruit is more abundant rather than when fruit is less available. Branch shaking, swinging, and moving around the tree crowns accompany the calling. This movement might be to show the other groups where they are.

The Siamang prefers calling in the living, high and big trees, it might be the places where another group is easy to see. Beside that, living, big, and tall trees can support Siamang movement. Calling trees are usually near feeding trees but sometimes they call in the feeding trees.

Siamang and their habitat

As a frugivorous animal, the Siamang disperses seeds through defacation as it travels across its territory. The Siamang can carry seed and defecate over 300 m with the shortest distance being 47.6 m from the seed resource, which supports the forest regeneration and succession.

Threats to population

The Siamang, as an arboreal primate, absolutely depends on the forest for existence, needing trees for its living. At the moment, the Siamang is facing a population decrease due to habitat loss, poaching and hunting.

Habitat loss

A major threat to the Siamang is habitat loss due to plantation, forest fire, illegal logging, encroachment, and human development. Firstly, palm oil plantations have removed large areas of the Siamang’s habitat in the last four decades. Since 2002 107,000 square kilometres of palm oil have been planted, which has replaced much rainforest in Indonesia and Malaysia, where the Siamang originally used to live. Secondly, in the last two decades, forest fire destroyed more than 20,000 km² of Sumatran rainforest, mainly in the lowland area where most of the Siamang live. Thirdly, the rate of illegal logging in Indonesia increased from 1980 to 1995 and even more rapidly after the reformation era beginning in 1998.These illegal activities devastated the remaining tropical rainforest especially in Sumatra. Fourthly, forest encroachments change forest cover into cultivated land, for example; the rising price of coffee in 1998 has been encouraging people in Sumatra to replace the forest with coffee plantation. Fifthly, development in many areas needs infrastructure such as roads, which now divide a lot of conservation areas have been caused forest fragmentation and edge effects. Unfortunately, the Siamang as an arboreal primate faces difficulty because road establishment has disconnected their pathways.

Poaching and hunting

Unlike other parts of Asia, primates are not hunted for their meat in Indonesia (the exception is in Chinese restaurants in Indonesia which sometimes serve macaque on their menu). However, they are poached and hunted for the illegal pet trade, mostly for infant Siamang. Poachers kill the mothers because mother Siamang are highly protective of their infants. It is therefore very difficult to remove the infant without first killing the mother. Despite the fact that most Siamang on the market are infants many infants nevertheless die during transportation.

Macaca fascicularis, Crab-eating Macaque, Kera kera

Macaca fascicularis

Crab-eating Macaque, Kera kera

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The Crab-eatingMacaca fascicularis, Crab-eating Macaque, Kera keraMacaque (Macaca fascicularis) is a primarily arboreal macaque native to Southeast Asia. It is also called the Cynomolgus Monkey, Philippine Monkey and the Long-tailed Macaque.

The scientific name of the Crab-eating Macaque is Macaca fascicularis. Macaca comes from the Portuguese word macaco, which was picked up from makaku, a Fiot (West African language) word (kaku means ‘monkey’ in Fiot). Fascicularis is Latin for ‘a small band’. Sir Thomas Raffles, who gave the animal its scientific name in 1821, did not specify what he meant by the use of this word although it is presumed it had something to do with his observation of the animal’s colour.

The common name of this animal varies. It is commonly referred to as the Long-tailed Macaque because the tail of this macaque is usually about the same length as its body and because its long tail distinguishes it from most other macaques. The species is also commonly known as the Crab-eating Macaque. Another common name for M. fascicularis is the Cynomolgous Monkey, which literally means “dog-milker” monkey, which is the name most commonly used for these animals in laboratory settings. In Indonesia, M. fascicularis and other macaque species are generically known as kera, possibly because of the high-pitched alarm calls they give when in danger (“krra! krra!”).


There is significant genetic diversity within the species and these differences are classified into at least 10 subspecies:

* Crab-eating Macaque, Macaca fascicularis fascicularis
* Burmese Long-tailed Macaque, Macaca fascicularis aurea
* Nicobar Long-tailed Macaque, Macaca fascicularis umbrosa
* Dark-crowned Long-tailed Macaque, Macaca fascicularis atriceps
* Con Song Long-tailed Macaque, Macaca fascicularis condorensis
* Simeulue Long-tailed Macaque, Macaca fascicularis fusca
* Lasia Long-tailed Macaque, Macaca fascicularis lasiae
* Maratua Long-tailed Macaque, Macaca fascicularis tua
* Kemujan Long-tailed Macaque, Macaca fascicularis karimondjawae
* Philippine Long-tailed Macaque, Macaca fascicularis philippinensis

Physical characteristics

Depending on sub-species, the body length of the adult monkey is 38-55 centimetres (15-22 in) with comparably short arms and legs. The tail is longer than the body, typically 40-65 cm (16-26 in). Males are considerably larger than females, weighing 5-9 kilograms (11-20 lb) compared to the 3-6 kg (7-13 lb) of female individuals.

Macaca fascicularis is a very social animal that lives in groups anywhere from 5-60+ animals. These groups are multi-male groups, normally containing 2-5 males and 2-3 times as many females. The number of immature is usually comparative to the number of females. Their group size often depends on the level of predation and availability of food. Their groups are female-centred, as the females are philopatric (i.e. remain in one place across generations) and the males move in and out of these female-based groups. Males generally first emigrate from their natal group at the age of 4-6. They will remain in a group up to four or five years and thus will emigrate several times throughout their life. These monkeys are highly despotic and have a strict dominance hierarchy. Adult males rank higher than females. Female ranks are more stable than males, as males from time-to-time will be defeated and lose rank. High-ranked males generally are more successful at reproduction and high-ranked females generally fare better at raising surviving offspring. The females are organized into matrilines, which are the female-based families consisting of the resident females and their offspring. Matrilines are ranked and some families have greater social power than others and this difference in rank is maintained over several generations. Matrilineal overthrows rarely occur and when they do they have severe consequences to the reproductive success of the defeated matriline in the following year.

After a gestation period of 167-193 days, the female gives birth to one infant. The infant’s weight at birth is approximately 350 grams (12 oz). Infants are born with black fur and this fur will begin to turn to a yellow-green, grey-green, or reddish-brown shade (depending on the sub-species) after about three months of age. It is suggested this natal coat indicates to others the status of the infant and other group members treat infants with care and rush to their defence when distressed. Newly immigrated males will sometimes commit infanticide on infants not their own, and high-ranked females sometimes kidnap the infants of lower-rank females. These kidnapping usually result in the fatality of the infants, as the other female usually is not lactating. Young juveniles stay with the mother and relatives mainly, and as male juveniles get older they become more peripheral to the group. Here they play together forming crucial bonds that may help them when the emigrate from their natal group. Males that emigrate with a partner seems to be more successful than those that move off alone. Young females on the other hand stay in the centre of the group and become incorporated into the matriline they were born into.

Results of a research shows that male Crab-eating Macaques will groom females in order to get sex. The study found that a female has a greater likelihood to engage in sexual activity with a male if he had recently groomed her, compared to males who had not groomed her.


Although members of this species are often referred to as Crab-eating Macaques, this name is something of a misnomer, since their diet is by no means limited to crabs. Other food items are in fact far more common. They are opportunistic omnivores, meaning they can and will eat a wide variety of animals, plants, and other materials. Although fruits and seeds make up 60 – 90% of the dietary intake, they also eat leaves, flowers, roots and bark, and also prey on vertebrates (including bird chicks and nesting female birds, lizards, frogs, fishes, et al.), invertebrates, and bird eggs. Although the species is ecologically well-adapted in its native range and poses no particular threat to the overall populations of prey species, in areas where the Crab-eating Macaque is non-native it can pose a substantial threat to biodiversity.

The Crab-eating Macaque is sometimes known as a “crop-raider”, feeding in cultivated fields on such items as young dry rice, cassava leaves, rubber fruit, taro plants, coconuts, mangos, and other crops, thus often causing significant losses to the cash incomes of local farmers. It also takes food from graveyards, garbage cans, and garbage pits. The species is often unafraid of humans, and is found in many cities and villages. It has been involved in aggressive interactions with people.

Distribution and habitat

Being “ecologically diverse”, the Crab-eating Macaque is found in a wide variety of habitats, including primary lowland rainforests, disturbed and secondary rainforests, and riverine and coastal forests of nipa palm and mangrove. They also easily adjust to human settlements and are considered sacred at some Hindu temples and on some small islands, while a pest when around farms and villages. Typically it prefers disturbed habitats and forest periphery. The native range of this species includes most of mainland Southeast Asia, including the Malay Archipelago islands of Sumatra, Java, and Borneo, the islands of the Philippines, and the Nicobar Islands in the Bay of Bengal.

Macaca fascicularis is an introduced alien species in several locations, including Hong Kong, western New Guinea, Anggaur Island in Palau, and Mauritius. Where they are non-native species — particularly on island ecosystems whose species often evolved in isolation from large predators — M. fascicularis is a documented threat to many native species. This fact has led the World Conservation Union (IUCN) to list M. fascicularis as one of the “100 Worst Alien Invasive Species”.[5] Insofar as they are present as an alien invasive on several islands, they have been labelled a “weed” species and are yet another significant ecological threat to those ecosystems and the species within them. It is important to note, however, that M. fascicularis is not a biodiversity threat in their native range, as other species therein have adapted to their presence through evolutionary time.

Relationship with humans

Macaca fascicularis has been used extensively in medical experiments, in particular those connected with neuroscience. It has also been identified as a possible vector for Ebola virus and monkeypox, and is a known carrier of B-virus (Herpesvirus simiae). Nafovanny is the largest captive-breeding non-human primate facility in the world, and houses 30,000 macaques. The Crab-eating Macaque is one of the types of monkeys that have been used as space test flight animals. It has been discovered recently that Plasmodium knowlesi, which causes malaria in M. fascicularis also can infect humans.

Conservation status

The Crab-eating Macaque has the third largest range of any primate species, behind only humans and the Rhesus Macaque. Since the wild harvest of the species for animal testing has been reduced by captive-breeding programs, the total population of M. fascicularis is not under significant threat. The IUCN Red List categorizes the species as “Lower Risk”; and CITES lists it as Appendix II (“not necessarily threatened with extinction, but in which trade must be controlled in order to avoid utilization incompatible with their survival”). The umbrosa subspecies is argued to be of important biological significance. It has been recommended as a candidate for protection in the Nicobar islands, where its small, native population has been seriously fragmented (Umapathy et al., 2003). One main conservation concern is that in areas where M. fascicularis is non-native, their populations need to be monitored, managed, or eradicated where they have a negative impact on native flora/fauna