Macaca fascicularislong-tailed macaque

Geographic Range

Long tailed or crab eating macaques (Macaca fascicularis) are found in southeast Asia from Burma to the Philippines and southward through Indochina, Malaysia, and Indonesia. They are found as far east as the Timor Islands.


Long-tailed macaques are "ecologically diverse." Some of the habitats in which they have been found are primary forests, disturbed and secondary forests, and riverine and coastal forests of nipa palm and mangrove. Long-tailed macaques live most successfully in disturbed habitats and on the periphery of forests.

In Sumatra, they achieve their highest population densities in mixed mangrove swamps, secondary hill forests, and riverine forests. Some were also observed in freshwater swamps, scrub grassland, lowland primary forests, and rubber groves.

In Thailand, long-tailed macaques occur in evergreen forests, bamboo forests, and in deciduous forests.

In Malaysia, they are abundant in coastal lowland forests.

This species has been observed drinking much water and eating crabs, they often live near bodies of water. Of the various habitats occupied by long-tailed macaques, the swamp forests seem to have the highest density of them.

In recent years, habitat alteration has expanded the range of some populations of long-tailed macaques. In Malaysia, cleared land, such as plantation areas, has been colonized by this species. It has been observed that some disturbed habitats have higher troop and population sizes than some pristine forests.

This species has the highest degree of arboreality of all macaque species. One study of long-tailed macaque behavior reported that they never came to the ground except within 5 m of the edge of a river near their tree. The population densities of this diurnal species vary from 10 to 400 per squared kilometer.

Physical Description

The body fur of long-tailed macaques tends to be grey-brown to reddish brown. These colors are always paler ventrally. The face is brownish-grey with cheek whiskers. The eyes are directed forward for binocular vision. The nose is flat and the nostrils are narrow and close together (catarrhine condition). Long-tailed macaques have shovel-shaped incisors, conspicuous canines, and bilophodont molars. The tooth formula is I 2/2, C 1/1, PM 2/2, and M 3/3.

The body length, not including the tail, is 40 to 47 cm. The greyish- brown or reddish colored tail is 50 to 60 cm. Long-tailed macaques exhibit sexual dimorphism in size. The average weight for males is 4.8 to 7 kg and 3 to 4 kg for females, approximately 69% of average male weight.

  • Sexual Dimorphism
  • male larger
  • Range mass
    3 to 7 kg
    6.61 to 15.42 lb
  • Range length
    40 to 47 cm
    15.75 to 18.50 in


In Sumatra, each social group of these monkeys contains an average of 5.7 males and 9.9 adult females. Although females outnumber males, indicating that males have more mates available to them than do females, both sexes may mate with multiple partners. However, the alpha male, or highest ranking male, of the group has the greatest access to mates of any males, and probably sires the most offspring.

Males reach sexual maturity at approximately 6 years of age, whereas females mature by about 4 years of age. Higher-ranking females become reproductively mature before lower-ranking females. The offspring of these higher-ranking females have a greater chance of survival than do the offspring of lower-ranking females. Both of these phenomena are related to the greater food availability and decreased amount of aggression experienced by the higher ranking females.

Female long-tailed macaques show a conspicuous cyclicity of sexual behavior during their menstrual cycle. As they approach ovulation, females experience a swelling of the skin in the perineal region. However, there has been no direct correlation between the frequency of copulation and the degree of swelling of genital tissues. This concealment of ovulation could exist in order to persuade consorting males to stay with females longer.

As a side effect of the prolonged estrus period and concealment of ovulation, it is difficult for humans to estimate the length of gestation. However, it seems likely that the gestation averages approximately 162 days. The average interbirth intervasl is approximately 390 days, indicating that females can produce young each year if high ranking, and every other year otherwise.

Young are nursed until they are approximately 420 days of age. The average interbirth interval is reported to be 390 days, which is less than the average time until weaning. Both the length of nursing and the interbirth interval may be affected by the rank of the mother.

It is known that the births in this species peak from May to July, corresponding with the rainy season.

  • Breeding interval
    Females have an average interbirth interval of 390 days.
  • Average number of offspring
  • Average number of offspring
  • Average gestation period
    162 days
  • Average gestation period
    165 days
  • Average weaning age
    420 days
  • Average age at sexual or reproductive maturity (female)
    4 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1238 days
  • Average age at sexual or reproductive maturity (male)
    6 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1544 days

As in all primates, there is an extended period of juvenile dependence. Females provide the bulk of the care for offspring. The young receive nourishment, encouragement, grooming, protection, and teaching from the mother. Young females are likely to remain in the troup into which they were born, whereas males are likely to emmigrate at or near sexual maturity.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents
  • extended period of juvenile learning
  • inherits maternal/paternal territory
  • maternal position in the dominance hierarchy affects status of young


Although the lifespan of this species has not been reported, it is likely to resemble that of other members of the genus, which seem able to obtain an maximum age of around 30 years in captivity.


Long-tailed macaques live in multi-male groups consisting of about thirty members. At sexual maturity, males leave their natal group, and join either bachelor groups or new social groups. Since males leave the natal group, they are subject to more predation, disease, and injury thna are females. Once a male finds another group in which to reside, he may replace some of the existing high-ranking males. Male replacement itself is a process in which a foreign male adult successfully takes over a resident male's harem position. These events are highly aggressive activites, and the participating adults are usually injured.

Despite aggression between males, this species is characterized by a genral lack of aggression between groups. Intergroup interactions are avoided/ When these groups meet, there tend to be high levels of aggression, involving chasing the non-resident group out of the area. Loud vocalizations and branch-bouncing are characteristic parts of these interactions. Males and females may use open mouth threats. This involves showing the enemy the incisors and canines, and pulling the ears and nose back. The alpha male is usually the one who leads the aggression by doing 90% of the branch-bouncing.

Within groups, a strict linear dominance hierarchy develops among males. This hierarchy is determined by such factors as age, size, and fighting skills.

Since females do not disperse, they are the stable core of a group. Females have a tendency to have close bonds with their maternal relatives throughout their lives. There is, however, a dominance hierarchy among females in a group. The acquisition of rank involves active intervention by maternal kin, and the differential treatment by unrelated members of the group. Grooming among females is a common activity. It is especially common for low-ranking females to groom higer-ranking females. This allows the lower-ranking females to receive less harassment, more support in aggresive interactions, and access to limited resources.

Long-tailed macaques are unique among other non-human primates because of their ability to show learned or cultural behavior. This cultural behavior was observed in the preparation of food by long-tailed macaques. On one occasion, an adult female dipped a piece of fruit into a river and then she consumed it. It was proposed that perhaps the female was cleaning sand off the fruit. Scientists investigated this further on other individuals who showed this behavior. Some of the macaques washed sandy fruit in the river, but some of them also washed fruit the scientists had cleaned prior to distributing them. There were also long-tailed macaques that simply ate the cleaned fruits without washing them. The controversy of what cultural behavior means is still being researched.

  • Average territory size
    1.25 km^2

Home Range

The day range of this species averages 1,900 square meters. The total of all the day ranges, or the home range, of this species averages 125 hectares.

Communication and Perception

As in other species of the genus Macaca, it is likely that these animals use a combination of visual (facial expression, body postures), auditory (vocalizations), physical (grooming, play, mating, aggression) and possible chemical (olfactory) signals as a part of their repertoire of communication.

Food Habits

Long-tailed macaques are omnivores, and exploit many different food types, reflecting the diversity of habitats they can utilize. The average length of feeding bouts is 18.3 minutes. There may be on average of twenty bouts per day. They eat a wide variety of foods such as fruits, crabs, flowers, insects, leaves, fungi, grasses, and clay. Clay may be eaten for the potassium found in it, although the potassium levels in the clay are low. However, 96% of the feeding time per day is spent eating fruit. Some limited observations suggest that long-tailed macaques select fruit based on ripeness, which is based on color.

  • Animal Foods
  • insects
  • aquatic crustaceans
  • Plant Foods
  • leaves
  • fruit
  • flowers
  • Other Foods
  • fungus


The predators of this species have not been reported.

Ecosystem Roles

To the extent that these animals are prey for other species, they may affect populations of those species. Macaca fascicularis may be an important predator in its ecosystem, and may have some impact on prey species.

Economic Importance for Humans: Positive

Long-tailed macaques, along with other species of macaques, have benefited humans through their use as research models in immunology, surgery, toxicology, and pharmacology. They are also important members of ecosystems and may serve as a basis for ecotourism ventures. They are sometimes still hunted for food.

Economic Importance for Humans: Negative

Long-tailed macaques have been known to feed in cultivated fields on such items as young dry rice, cassava leaves, rubber fruit, taro plants, and other crops. They also take food from graveyards, garbage cans, and garbage pits. They have also become involved in aggresive interactions with people.

  • Negative Impacts
  • injures humans
    • carries human disease
  • crop pest

Conservation Status

There are nine national parks, nine reserves, and two sanctuaries in which some long-tailed macaques reside. Regardless of the type of habitat, there must be at least 500 squared kilometers of habitat necessary to support a viable population of 5,000 long-tailed macaques. This is the minimum size for a reserve for this species.

Long-tailed macaques receive some protection in temple ruins in Thailand and protection and food in temples in Bali. In Malaysia, long-tailed macaques are legally protected, and they are fed and protected in urban forests and parks. In the Philippines, there is much interest in protecting this species. In Indonesia, the species is well-protected, but some of the reserves are being considered for oil drilling and harvesting. Some people in Bali, in fact, consider these primates to be sacred. This may increase the chances of their survival in these reserves. In Thailand, long-tailed macaques may be hunted, captured, or kept in captivity only under license. The export of this species is regulated by a quota system.

Although there are some sanctuaries for long-tailed macaques, hunting is still a problem. In Thailand and Borneo, they are hunted for food. This species is also killed because it is a pest to agriculture. The fact that these macaques destroy crops has prevented some governments from making serious conservation efforts. Long-tailed macaques are collected for medical research. They are one of the five most used primate species in medical research. Many of these macaques were exported to the United States and Great Britian. Habitat loss in these organisms is occurring due to extensive logging operations.

Other Comments

The long-tailed macaque is also called the crab-eating macaque, or the cynomolgus or 'java' monkey.


Nancy Shefferly (editor), Animal Diversity Web.

Christopher Bonadio (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.



uses sound to communicate


living in landscapes dominated by human agriculture.


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.


Referring to an animal that lives in trees; tree-climbing.

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.

brackish water

areas with salty water, usually in coastal marshes and estuaries.


uses smells or other chemicals to communicate


the nearshore aquatic habitats near a coast, or shoreline.

  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates


humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.


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.


A substance that provides both nutrients and energy to a living thing.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


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).


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


an animal that mainly eats all kinds of things, including plants and animals


found in the oriental region of the world. In other words, India and southeast Asia.

World Map


the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.


having more than one female as a mate at one time


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.


Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.


a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.


uses touch to communicate


Living on the ground.


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


the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.


uses sight to communicate


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.


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Melnick, D., M. Pearl. 1987. Cercopithecines in Multimale Groups: Genetic Diversity and Population Structure. Pp. 121-134 in B Smuts, D Cheney, R Seyfarth, R Wrangham, T Struhsaker, eds. Primate Societies. Chicago and London: University of Chicago.

Paul, A., J. Kuester. 1996. Differential Reproduction in Barbary Macaques. Pp. 309-313 in J Fa, D Lindberg, eds. Evolution and Ecology of Macaque Society. New York: Cambridge University Press.

Payne, Junaidi, F., Phillipps, Karen. 1985. The Field Guide to the Mammals of Borneo. Petaling Jaya, Malaysia: Setiakawan Printers Sdn. Bhd..

Visalberghi, E., D. Fragaszy. 1990. Food-Washing behaviour in tufted capuchin monkeys, Cebus apella, and crabeating macaques, Macaca fascicularis. Animal Behaviour, 40: 829-836.

Wolfheim, J. 1983. Primates of the World: Distribution, Abundance, Conservation. Seattle and London: University of Washington Press.

Zeller, A. 1996. The inter-play organisation and facial communication in the macaques. Pp. 527-529 in J Fa, D Lindberg, eds. Evolution and Ecology of Macaque Society. New York: Cambridge University Press.