Crab-Eating Macaque Fact File

Macaca fascicularis

Credit: Public Domain








Wild 20 years

Captive 35 years



Eggs, Fruit, Leaves

Conservation Status



The crab-eating macaque is named for its ability to dive in to mangrove swamps where they will capture crabs to feed on. Despite their name this behavior is not performed across their entire range.

They are omnivores which feed primarily on plant matter such as leaves, fruit and flowers. This is supplemented with animal prey such as eggs, molluscs, birds, invertebrates and small vertebrates.

Troops of up to 30 crab-eating macaques will form which have a dominance hierarchy.

These animals are threatened through capture for use in medical research, habitat loss and hunting.

Read on to learn more about these magnificent mammals.


What does the crab-eating macaque look like?

Crab-eating macaques are covered by fur which is grey, dark brown or yellowish-brown. They have lighter fur on the underside. On top of the head is a small crest of hairs.

Their face features areas of bare pink skin. On the feet and ears they have black colored skin.

At the end of their body is a long tail which measures between 40 and 65cm (16-26in) long. It is colored dark grey or brown. Their tail is an adaptation which helps them to balance when climbing through the trees.

An average crab-eating macaque will measure 40-47cm (16-19in) long with a weight of between 3 and 7kg (6.6-15lbs). Males are significantly larger than females.


What does the crab-eating macaque eat?

The crab-eating macaque is an omnivore. These animals will feed on leaves, fruit, flowers, invertebrates, birds, eggs and small vertebrates. Plant matter may make up as much as 90% of their diet.

While named for eating crabs this is only common in some parts of their range. They will dive in mangrove swamps to source these.

They make use of their cheek pouches to store food when they are foraging.

These primates have been observed to use tools to obtain their food. This includes using stones to open the shells of molluscs.

In areas inhabited by humans these animals will raid cultivated fields along with garbage cans and refuse piles. Occasionally they will also take food directly from humans.

Crab-Eating Macaque

Credit: Public Domain


Where can you find the crab-eating macaque?

Asia is the native home of the crab-eating macaque. Here they can be found in the following countries - Bangladesh; Brunei Darussalam; Cambodia; India; Indonesia; Lao People's Democratic Republic; Malaysia; Myanmar; Philippines; Singapore; Thailand; Timor-Leste and Viet Nam.

Introduced populations of this species are found in Mauritius; Palau and Papua New Guinea.


What kind of environment does the crab-eating macaque live in?

These animals make their home in forests and wetlands. They may also be found in agricultural areas.

-- AD --


How does the crab-eating macaque produce its young?

Births will peak in this species from May to July. Males and females will both mate with multiple partners within their troop.

When females are approaching ovulation they will experience swelling in their perineal region.

A single infant is born following a 5.5-6 month gestation period. At birth the young have black fur which will lighten as they age.

Mothers provide care and milk to their infant for up to 1 year. Females provide most of the care to the their young.

If a new male enters the troop he may go through and kill any young which are present in the troop. Dominant females may also kidnap the young of lower ranked individuals. As they are typically not lactating this causes the death of the infant.

Sexual maturity is reached between 4 and 5 years old. Males will leave their birth group and find a troop to join while females remain in their group.


What does the crab-eating macaque do with its day?

Crab-eating macaques are excellent swimmers and adept climbers.

These animals are active during the day.

This species will live in a troop of up to 30 individuals. This is compromised mostly of females and their young with one or a few males.

Individuals within the troop will groom one another to reinforce bonds. It also increases the chance of females mating with males which have groomed her recently.

The crab-eating macaques have a dominance hierarchy within the females in the troop. Dominant individuals will have the first access to food and resting sites. Males also have a dominance structure to maintain breeding rights with the females.

Crab-Eating Macaque

Credit: kallerna, CC BY-SA 3.0 <>, via Wikimedia Commons

Predators and Threats

What is impacting the survival of the crab-eating macaque?

Natural predators of the crab-eating macaque include lizards such as the Komodo dragon, cats such as leopards and pythons.

They may jump in to the water to help them escape predators.

Populations of the crab-eating macaque are decreasing in number across their range. In much of their range this species is considered common but in Bangladesh the population is estimated at less than 100 total individuals.

This species is subject to hunting across its range. The species is also exported for use in a laboratory research facilities.

They are seen as a pest in some areas which can lead to persecution.

Habitat loss is a threat in some areas of their range.

Quick facts

The crab-eating macaque has been worshipped on the island of Bali. Large groups are housed at holy temples.

They may also be known as the common long-tailed macaque or the cynomolgus monkey. This name is primarily used in laboratories and means dog-skin monkey.

These animals were described for western science in 1821 by Sir Thomas Raffles.

Crab-Eating Macaque

Credit: kallerna, CC BY-SA 3.0 <>, via Wikimedia Commons


Verhoef-Verhallen, E., 2006. The complete encyclopedia of wild animals. Netherlands: Rebo International.

Jackson, T. and Chinery, M., 2012. The illustrated encyclopedia of animals of the world. London: Southwater.

Eudey, A., Kumar, A., Singh, M. & Boonratana, R. 2021. Macaca fascicularis (amended version of 2020 assessment). The IUCN Red List of Threatened Species 2021: e.T12551A204494260. Downloaded on 16 November 2021. 2021. Crab-eating Macaque - Invasion Biology Introduced SpeciesSummary Project - Columbia University. [online] Available at: <> [Accessed 16 November 2021].

Thai National Parks. 2021. Macaca fascicularis, Crab-eating macaque. [online] Available at: <> [Accessed 16 November 2021].

Basel, Z., 2021. Crab-eating macaque, long-tailed macaque. [online] Available at: <> [Accessed 16 November 2021].

Bonadio, C. 2000. "Macaca fascicularis" (On-line), Animal Diversity Web. Accessed November 15, 2021 at

Indianapolis Zoo. 2021. Discover the Macaque | Our Animals | Indianapolis Zoo. [online] Available at: <> [Accessed 16 November 2021].

Most Popular Animal this Week

Credit: Under License

Redbubble Store.

Similar Species

Japanese macaque
lion tailed macaque

Latest primate news stories

Sumatran Orangutan Passes Away at Zoo Atlanta
Zoo Atlanta Mourn the Passing of Sumatran Orangutan Biji
Squirrel Monkey Infants Taronga Zoo
Squirrel Monkey Troop Ready for Mother’s Day at Taronga Zoo


Copyright The Animal Facts 2023

Share via
Copy link
Powered by Social Snap