Long-Tailed Macaque

Long-Tailed Macaque

Crab-eating macaque, Cynomolgus monkey, "Java” monkey

Macaca fascicularis
Population size
Life Span
15-30 years
kg lbs 
cm inch 

The Long-tailed macaque (Macaca fascicularis) is a cercopithecine primate native to Southeast Asia. This species has a long history alongside humans. It has been alternately seen as an agricultural pest, a sacred animal, and, more recently, the subject of medical experiments.


The body length of the adult Long-tailed macaque varies among subspecies, however, males are considerably larger than females. The upper parts of the body are dark brown with light golden brown tips. The underparts are light grey with a dark grey/brown tail. Long-tailed macaques have backwards-directed crown hairs which sometimes form short crests on the midline. Their skin is black on their feet and ears, whereas the skin on the muzzle is a light grayish-pink color. The eyelids often have prominent white markings and sometimes there are white spots on the ears. Males have a characteristic mustache and cheek whiskers, while females have only cheek whiskers. Long-tailed macaques have a cheek pouch which they use to store food while foraging.




Long-tailed macaques are found throughout south-eastern Asia. Their range extends from the southeastern tip of Bangladesh southwards to Malaysia and the Maritime Southeast Asia islands (including Sumatra, Java, and Borneo), offshore islands, the Philippines as well as the Nicobar Islands in the Bay of Bengal. The ideal habitat for Long-tailed macaques is disturbed areas and forest periphery. However, they occur in different habitats from primary lowland rainforests and disturbed, secondary rainforests to shrubland, riverine, and coastal forests of nipa palm, mangroves, and even human settlements.

Long-Tailed Macaque habitat map

Climate zones

Long-Tailed Macaque habitat map
Long-Tailed Macaque
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Habits and Lifestyle

Long-tailed macaques are diurnal and highly social creatures, forming groups of 1 or more males as well as 3-20 females with their young. As a general rule, the majority of mature individuals in a group are females. Males usually disperse upon reaching maturity to form new groups or join bachelor herds. Males live in a well-defined linear hierarchy system, where individuals are ranked depending on age, size, and fighting skills. Young females, on the other hand, remain with their natal group, forming the core of the group. Related females typically live in close relationships. Overall, females of this species commonly practice mutual grooming, where lower-ranking individuals groom higher-ranking ones, due to which the former avoid intimidation, and get support during conflicts as well as access to limited resources of the group.

Seasonal behavior

Diet and Nutrition

As omnivorous animals, Long-tailed macaques consume food of both plant and animal origin. They eat fruits, crabs, flowers, leaves, fungi, grasses, and clay, supplementing this diet with various insects.

Mating Habits

most births occur in May-July
162-193 days
1 infant
420 days

Long-tailed macaques exhibit polygynous (one male mates with multiple females) and polygynandrous (promiscuous) (multiple males mate indiscriminately with multiple females) mating systems. Most births occur in May-July, during the rainy season. The gestation period lasts for 162-193 days, after which high-ranking females usually give birth to a single infant at an interval of 390 days, while others produce offspring every 2 years. The newborn baby is nursed until 420 days old. The age of reproductive maturity is 6 years old in males and 4 years old in females.


Population threats

Threats to the population of this species vary, depending on geographical location. For example, Long-tailed macaques in the Philippines are hunted for food and sport. On the other hand, those in the mainland areas (including Cambodia and Vietnam) are commonly captured by humans: while females are taken for breeding, males are used in laboratory research. In certain parts of their range, these animals are considered pests and hence persecuted. In other areas, they face the loss of their natural habitat. However, these primates are highly adaptable by nature and are capable of living in a wide range of environments.

Population number

The IUCN Red List and other sources don’t provide the number of the Long-tailed macaque total population size. However, as reported on the IUCN Red List, a specific population has been estimated in the Lao PDR and consists of 300-500 individuals. Currently, this species is classified as Endangered (EN) on the IUCN Red List, and its numbers today are decreasing.

Ecological niche

Long-tailed macaques eat durians and are considered a major seed disperser for this fruit.

Fun Facts for Kids

  • One of the most unusual features of these primates is their ability to display learned or cultural behavior. This is primarily associated with the preparation of food. For example, an adult female of this species has been recorded dunking a piece of fruit into the river before eating it, evidently in order to clean the sand off the meal.
  • Sleeping sites of Long-tailed macaques are situated in trees, growing along rivers. An ideal sleeping site is one, located at the top or crown of a tree, preferably at the edge of a branch, which overhangs the river. Each group occupies a single tree. When sleeping, these animals huddle together to conserve heat.
  • Good swimming abilities allow these primates to escape predators. They usually enter the water for refuge when threatened.
  • Long-tailed macaques are primarily frugivorous animals. Thus, about 96% of their feeding time is spent on consuming fruits. According to a few observations, they choose fruits depending on ripeness, which they recognize by color.
  • These primates are known to use tools in daily life. In order to break the shells of crabs, they use rocks. Meanwhile, nuts, oysters, and teeth help them peel the skin of sweet potatoes.
  • The main forms of communication include vocalizations, visual signals such as body posture as well as olfactory communication such as a chemical substance that the body gives off.
  • Newborn babies of this species exhibit black overall coloration, which gradually changes as they grow up.


1. Long-Tailed Macaque Wikipedia article - https://en.wikipedia.org/wiki/Crab-eating_macaque
2. Long-Tailed Macaque on The IUCN Red List site - http://www.iucnredlist.org/details/12551/0

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