The Sunda pig-tailed macaque spends more time on the forest floor and in the open than other macaques, where it forages for leaves, buds, shoots, insects and small animals (5). It has cheek pouches to carry food while it forages, and often returns to the safety of the trees to feed (5). This macaque is a social primate and lives in group sizes of 5 – 40 (average 15 – 22) individuals (2), though the group splits into smaller units to forage. In the group males and females live together. Females remain in their natal group, though males will disperse shortly before they reach sexual maturity (5).

The Sunda pig-tailed macaque is a rare primate of the Southeast Asia. It is characterised by its short tail that is carried half-erect and somewhat resembles a pig's, hence its common name (3). Macaques are medium to large sized monkeys with stout bodies. This species has a brown coat with a lighter underside and its legs are long and strong. The muzzle is long and lacks hair (3) though males have mane-like hairs surrounding the face, giving them a majestic appearance (4). When females are receptive to mating they develop large swellings on the rump. Adult females can also be identified because they are around half the size of males (4).

This species is found in Brunei, Indonesia (Bangka, Kalimantan Borneo, and Sumatra), Malaysia (including the Malay Peninsula and Sabah and Sarawak Borneo), and southern peninsular Thailand. There are small, introduced populations on Singapore and in the Natuna Islands (Groves 2001). The precise geographic boundary between M. nemestrina and M. leonina is not well defined. There are populations of the two taxa found on either side of the distribution limit in the Isthmus of Kra, but many of these populations are the result of release by humans. The two species hybridize in a small area of southern peninsular Thailand, as well as on the islands of Phuket and Yao Yai (Groves 2001).

Pigtail macaques are widely distributed throughout Southeast Asia in the oriental biogeographic region. They are found in many countries including India (northeast), China (south), Indonesia (Borneo, Kalimantan, Sumatra), Bangladesh (east), Burma, Thailand, Laos, Cambodia, Vietnam, Malaysia (Malay Peninsula) (Cawthon Lang, 2009). Also found in Assam, Yunnan, Indochina, Bangka, and neighboring islands (Nowak, 1999).

Macaque species are often capable of being introduced into other areas of the world with success. Pigtail macaques have been introduced in Singapore and the Natuna Islands (Nowak, 1999).

Biogeographic Regions: oriental (Introduced , Native )

This species is found in Brunei, Indonesia (Bangka, Kalimantan Borneo, and Sumatra), Malaysia (Sarawak and Sabah Borneo, plus the Malay peninsula), and southern Thailand, with introduced populations on Singapore and in the Natuna Islands (2).

Pigtail macaques get their name from a unique feature of their morphology. Their short tails, which they carry half-erect, resemble the tails of pigs, thus giving them their name "pigtail" macaque. Their tails also have very little hair or no hair at all (Cawthon Lang, 2009). Tail length for females varies from 130 mm to 253 mm and for males the tail length varies from 160 mm to 245 mm (Rowe, 1996).

Pigtail macaques have light brown hair covering their bodies and white underbellies. The hair on the top of their heads is either dark brown or black and grows so that it looks like they have an indentation on the tops of their heads (Cawthon Lang, 2009). Males have mane-like hair around their faces (Wildscreen, 2003). Pigtail macaques also have long legs and hairless snouts (Wildscreen, 2003). Infant pigtail macaques are born black and develop adult coloration as they age (Cawthon Lang, 2009).

Pigtail macaques are sexually dimorphic, with males being larger (Cawthon Lang, 2009). Females are roughly half the size of males (Wildscreen, 2003). The average length of males varies from 495 mm to 564 mm. The average weight of males varies from 6.2 kg to 14.5 kg. The average length of females varies from 467 mm to 564 mm. The average weight of females varies from 4.7 kg to 10.9 kg (Cawthon Lang, 2009; Rowe, 1996). Males also have large canine teeth that average 12 mm in length. These teeth are often used in agonistic encounters (Cawthon Lang, 2009). The average length of female canine teeth is 7.3 mm (Rowe, 1996).

The average weight of the brain of an adult pigtail macaque is 106 g (Rowe, 1996). Pigtail macaques move around on the ground and throughout the trees on all fours (quadrupedally) (Cawthon Lang, 2009).

Range mass: 4.7 to 14.5 kg.

Range length: 467 to 564 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; sexes shaped differently

Type for Macaca nemestrina
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Male;
Preparation: Skin; Skull
Collector(s): C. Adams
Year Collected: 1887
Locality: Sapagaya River, Borneo, Sabah, Malaysia, Asia

Habitat and Ecology

Systems

• Terrestrial

Pigtail macaques live in elevations starting at sea level and ranging to above 2000 m. They live in forests, mostly rainforests, and swamps. They prefer dense, humid rainforest with temperatures ranging from 18 to 30 degrees Celsius (64 to 86 Fahrenheit). Temperatures change seasonally and vary regionally. Rainforests they inhabit also get more than 2500 mm (8.20 ft) of rain each year.

Range elevation: 0 to >2000 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: rainforest

Wetlands: swamp

Inhabits lowland primary and secondary forest, as well as coastal, swamp and montane forest (2).

Pigtail macaques are primarily frugivorous. The vast majority of the foods that they eat are fruits, but they also eat insects, seeds, leaves, dirt, and fungus (Cawthon Lang, 2009). Other foods in the diet of pigtail macaques include nestling birds, termite eggs and larvae, and river crabs (Rowe, 1996). Pigtail macaques are ground foragers. They divide into small groups while foraging (about 2 to 6) but keep in contact with the other groups through vocalizations. They range widely when searching for food. Pigtail macaques are known for raiding the fruit crops of farmers. They will set up a guard to look for humans and shout a warning signal to those in the fields (Cawthon Lang, 2009).

Research in captivity has looked at which types of fruits and vegetables are preferred by pigtail macaques. The foods chosen at the highest frequency by the pigtail macaques studied were mango and pineapple. The food chosen least was carrots (Laska, 2001).

Animal Foods: birds; insects; aquatic crustaceans

Plant Foods: leaves; seeds, grains, and nuts

Other Foods: fungus

Primary Diet: herbivore (Frugivore )

Pigtail macaques affect their ecosystems with their foraging habits. By eating the fruits, leaves, and other vegetation they participate in spreading seeds around the forest. Their diets include many fruits, plants, fungus and other living things such as insects, nestling birds, and river crabs.

Pigtail macaques are also known to participate in exploitative and interference competition with white-handed gibbons (Hylobates lar). This in turn affects the amount of resources available to white-handed gibbons (Whitington, 1992).

One study of a colony of pigtail macaques in captivity showed them to be intermediate hosts of the parasite Echinococcus granulosus. Pigtail macaques can become infected with this by eating E. granulosus eggs in the feces of canids. Canids are the definitive host of this parasite.

About 90% of macaques and old-world monkeys are infected with respiratory mites. These mites affect the lungs of the monkeys.

A study was conducted on parasites in an outdoor breeding colony in Louisiana. The study included baboons, rhesus macaques, and pigtail macaques and the data reflect the parasites for all three species combined. The study did a fecal and blood survey of over 4000 of the animals. Endemic pathogenic intestinal parasites included Trichuris trichiura found in 35%, Strongyloides fülleborni found in 34%, Balantium coli found in 21%, and Giardia lamblia found in 0.3%. Only one endemic pathogenic blood parasite was found, which was Trypansoma cruzi in 0.8%.

Ecosystem Impact: disperses seeds

Commensal/Parasitic Species:

• Echinococcus granulosus
• respiratory mites
• Trichuris trichiura
• Strongyloides fülleborni
• Balantium coli
• Giardia lamblia
• Trypansoma cruzi

Perhaps one of the biggest predators of pigtail macaques is humans. Pigtail macaques are hunted and killed by humans for food, medicinal purposes, and for research (Cawthon Lang, 2009). Native predators are not reported, but are likely to include large felids or snakes.

Pigtail macaques often come in contact with white-handed gibbons (Hylobates lar). White-handed gibbons compete with the pigtail macaques for resources and are often an annoyance to pigtail macaques (Rowe, 1996).

Known Predators:

• humans (Homo sapiens)

Some researchers describe pigtail macaques as silent monkeys because they seem to be very quiet. When seen running away after an episode of crop raiding, pigtail macaques are almost completely silent. This silent tactic is not limited to simply crop raiding and shows up in most encounters where pigtail macaques are fleeing a certain area. However, they do make a lot of vocalizations. The most often used vocalization when moving through the middle and upper canopies of the rainforest is the “coo.” It is generally used while pigtail macaques are foraging and can be either a short call or a long call, depending on the information being exchanged. Some other vocalizations are made when pigtail macaques are being threatened or endangered, especially during agonistic encounters with other pigtail macaques. These other sounds include “squeals,” “screams,” “growls,” “barks,” and “screeches.”

Pigtail macaques use other forms of communication like visual cues and body postures. Both males and females use a form of puckering to communicate. Males use their lips to attract females who are in estrous for mating, which generally occurs right after the communication exchange. But males also direct this facial expression to other males. In this case, it usually makes the lower-ranking male withdraw from the encounter. Another way to threaten other males is to shake branches. This is also used to attract females for copulation. Pigtail macaques use another very common facial expression that includes bared teeth and silence. However, unlike the puckering lips, lower-ranking males direct this signal to more dominant males. Females have their own form of visual cues. When in estrous they get large anogenital swellings that turn a purple-pink color. This allows males to know that they are ready for copulation. Like other primates, touch and chemical cues also are likely to play a role in social communication.

Communication Channels: visual ; tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

Pigtail macaques have an expected lifespan of about 26 years in the wild if they survive to sexual maturity. Captive individuals have lived up to almost 35 years.

Range lifespan

Status: wild: 30 (high) years.

Average lifespan

Status: wild: 26 years.

Range lifespan

Status: captivity: 34.3 (high) years.

Average lifespan

Status: captivity: 27.1 years.

Maximum longevity: 37.6 years (captivity)

Pigtail macaques are not monogamous and females will mate with multiple males during a lifetime. They do not discriminate between adolescents and adult males. When there are only a few females that are in estrus, the highest ranking males will be able to monopolize them. They can keep younger and lower-ranking males from attempting to mate and will often act aggressively toward the male and the female if the lower-ranking male attempts to copulate. However, if there are more than a few females in estrus, the top ranking males cannot effectively control females and lower-ranking males gain opportunities to copulate. When a female reaches sexual maturity at 3 years of age, she can present herself to males with her anogenital swelling during estrus for reproduction. When this time comes, the female will show her backside, including her anogenital swelling, and look over her shoulder at the male. The male will then draw back his ears and push his lips outward.

Although higher-ranking males are generally able to copulate more frequently with more females, this does not mean that they produce more offspring than do lower-ranking males. According to a study done with captive pigtail macaques, female rank is more important to reproductive success. It also helps to determine the sex of offspring. Higher-ranking female pigtail macaques will produce female offspring. This is because female infants are more energetically expensive. They require a lot more attention from their mothers because they stay with the group and nurse more often. Higher-ranking females can benefit from this because they gain allies in their daughters. Lower-ranking females will give birth to male offspring because they nurse less often and do not require as much attention. Once they are old enough they leave the group to join another group, hopefully gaining a higher position in that group through competition.

Mating System: polygynandrous (promiscuous)

Pigtail macaques are year-round breeders. However, there is a slight increase during the months of January and May. Females have reproductive cycle of about 30 to 35 days and during this time display a large, purple-pink anogenital swelling. They give birth to single infants after a gestation period between 162 and 186 days. Young pigtail macaques are then nursed for 8 to 12 months. After one year pigtail macaques are considered adolescents until they reach reproductive maturity at the age of 3 years old for females and 4.5 years old for males.

Breeding interval: The breeding interval is between 1 year and 2 years.

Breeding season: Pigtail macaques breed throughout the year.

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Range gestation period: 162 to 186 days.

Average gestation period: 171 days.

Average weaning age: 12 months.

Range time to independence: 8 to 12 months.

Range age at sexual or reproductive maturity (female): 3 to 3.5 years.

Range age at sexual or reproductive maturity (male): 4 to 4.5 years.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Females provide the majority of care for the young. Mothers nurse young, carry them, and protect them throughout their first year of life. After that they still provide some care, especially to female offspring, generally through grooming and social support. This can last throughout their whole lives or until they leave the natal group.

During the first month of their lives, offspring and mothers are hardly ever separated. After the fifth week though, the infant will separate from its mother and begin to explore its surroundings. This can cause problems because the infant is then in danger of being kidnapped by other adult females. This is particularly the case when higher-ranking females seize lower-ranking female’s offspring. However, if the infant is separated from its mother for too long, it will more than likely die from starvation or dehydration.

When pigtail macaques are born they have a black coat, but by the third month of life, this starts to change to an olive brown, which is typical of adults. At one year old pigtail macaques are no longer considered infants. After one year pigtail macaques are considered adolescents until they reach reproductive maturity at the age of 3 for females and 4.5 for males.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); post-independence association with parents; extended period of juvenile learning; maternal position in the dominance hierarchy affects status of young

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Species: 10
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 2000
  Vulnerable
• 1996
  Vulnerable
• 1994
  Commercially Threatened
  (Groombridge 1994)

Pigtail macaques are classified as vulnerable on the IUCN redlist. Their vulnerability comes from many sources. The first source that poses a threat for the pigtail macaques is destruction of their natural habitat. From large scale timber companies cutting down trees to small families taking wood for fire or building, each time forests are cut, pigtail macaque habitat is destroyed. Effective protection of forested habitat and education of local people is necessary to help protect this species.

Pigtail macaques are often killed by locals for food. They are being shot and killed at higher rates in some places, such as Borneo, where they are becoming rare (Nowak, 1999). Pigtail macaques are also targeted in order to become the subjects of biomedical research especially for research on HIV/AIDS (Cawthon Lang, 2009).

Another threat to pigtail macaques, especially in India, is the effects of the nearby coal mines. Pollution from the coal mines is harmful to the pigtail macaques that live nearby. This problem could be solved by the Indian government taking steps to regulate the coal mining system.

One promising conservation effort was reported in a study by Steinmetz, Chutipong, and Seuaturien (2006). They led wildlife workshops in local villages in Southeast Asia in order to teach villagers about the status of endangered animals (including pigtail macaques) and what to do to help these animals thrive. The workshops involved assessing the level of danger to the animals, determining what activities were leading to the endangerment of the species, and coming up with a plan of action to protect the species. The study also involved inter-village cooperation. Villages were brought together to understand and help these endangered animals. This study had promising results that led to less killing of pigtail macaques in the villages that participated. It is possible that implementing more educational workshops and cooperative programs could lead to helping change the vulnerable status of pigtail macaques and other species.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: vulnerable

Classified as Vulnerable (VU) on the IUCN Red List 2006 (1).

Population

Population Trend

Major Threats

This species faces many threats. Destruction of forests by felling, encroachment, slash and burn cultivation of the hill tribes and monoculture are all major threats to the Sunda pig-tailed macaque's habitat (1). The rate of forest destruction is alarming, and is not only reducing this primate's habitat, but also fragmenting it. The macaque's taste for agricultural crops has also deemed it a pest, and it is therefore frequently shot on sight (2). Furthermore, Sunda pig-tailed macaques are very popular for use in laboratories, being almost ideally suited for both psychological studies and HIV (AIDS virus) research (2).

Conservation Actions

The Sunda pig-tailed macaque is known to occur in 7 protected areas and is found in captivity in 26 zoos or institutions worldwide (2).

Pigtail macaques are pests to farmers because they often raid crops. They steal corn and coconuts from local crops and use lookouts to warn the group of the approach of humans (Cawthon Lang, 2009).

Negative Impacts: crop pest

Pigtail macaques have been domesticated and trained in some areas of the Malay peninsula by farmers to retrieve coconuts and other fruit from trees.

Pigtail macaques are sought for use in medical research, such as research on HIV. Local populations of humans hunt them for food.

Positive Impacts: food ; source of medicine or drug ; research and education