PIG-TAILED MACAQUES | Facts and Details

PIGTAIL MACAQUES

southern pig-tailed macaque

Pig-tailed macaques are relatively large monkeys native to Southeast Asia. Males can measure up to 65 centimeters (two feet) from the buttocks to the top of the head and weigh up to 18 kilograms (40 pounds). When threatened they screech and bare their canines. The buttocks of females become swollen and red when they are receptive to mating.

Pig-tailed macaques are regarded as "clever, political animals" with "good mother-infant bonding and particularly strong peer interaction and play." Their thick fur protects them from bees and stinging ants. In some parts of Malaysia, pig-tailed macaques are used to pick coconuts.

Pigtail macaques are widely distributed throughout Southeast Asia and found in Assam and northeast India, Yunnan and souther China, Borneo, Kalimantan, Sumatra in Indonesia, eastern Bangladesh, Myanmar (Burma), Thailand, Laos, Cambodia, Vietnam, Peninsular Malaysia and Bangka, and neighboring islands. Pigtail macaques have been introduced in Singapore and the Natuna Islands. [Source: Kayla Ayers and Candace Vanderpoel, Animal Diversity Web (ADW) /=]

Pigtail macaques mainly live in tropical areas in rain forests and swamps from sea level to more than 2000 meters (feet). They prefer dense, humid rainforest with temperatures ranging from 18 to 30 degrees Celsius (64 to 86 Fahrenheit). They tend to live in places with a rainy season and slight temperatures variations according to the seasons and regions. Rainforests they inhabit get as much as 250 centimeters (8.2 feet) of rain each year.

Pigtail macaques live in the wild is up to 30 years, with the average lifespan in the wild being estimated at 26 years. Their lifespan in captivity is up 34.3 years. Their average lifespan in captivity is 27.1 years.

Pigtail Macaque Characteristics

Pigtail macaques get their name from their short tails, which are semi-erect and resemble the tails of pigs. These also have very little hair or no hair at all and vary on length for females from from 1.3 centimeters to 2.5 centimeters and for males from 1.6 centimeters to 2.45 centimeters. [Source: Kayla Ayers and Candace Vanderpoel, Animal Diversity Web (ADW) /=]

range of the northern pig-tailed macaque

Pigtail macaques have light brown or russet hair 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. Males have mane-like hair around their faces. Both sexes have long legs and hairless snouts. Infant pigtail macaques are born black and lighten in color as they get older. The average weight of the brain of an adult pigtail macaque is 106 grams. Pigtail macaques move around on the ground and throughout the trees quadrupedally (on all fours).

Pigtail macaques range in weight from 4.7 to 14.5 kilograms (10.35 to 31.94 pounds) and range in length from 467 to 564 millimeters (18.39 to 22.20 inches). The are sexually dimorphix. Males are larger than females and males and females have different shapes. Males are roughly twice the size of females. The average length of males varies from 49.5 centimeters to 5.64 centimeters The average weight of males varies from 6.2 kilograms to 14.5 kilograms. The average length of females varies from 4.67 centimeters to 564 centimeters. The average weight of females varies from 4.7 kilograms to 10.9 kilograms. Males also have large canine teeth that average 1.2 centimeters in length. These teeth are often used in agonistic encounters — social interactions that involves aggression, threat, appeasement, and avoidance. The average length of female canine teeth is .73 centimeters.

Southern Pig-tailed Macaques Versus. Northern Pig-tailed Macaque

The main differences between the northern pig-tailed macaque and the southern pig-tailed macaque are their fur color, facial features, and tail length: Southern pig-tailed macaques are olive brown with a dark brown or black top of the head, while northern pig-tailed macaques are golden brown with a brown top of the head. Northern pig-tailed macaques have red streaks of fur extending from the outer corners of their eyes towards their ears. [Source: New England Primate Conservancy]

Northern pig-tailed macaques are also known as Macaca leonina, while southern pig-tailed macaques are commonly called Macaca nemestrina. Northern pig-tailed macaques have a stumpy tail that's usually about 23 cm long and is often held curled upwards. Southern pig-tailed macaques have short, hairless, or nearly-hairless tails that they carry half-erect.

Northern pig-tailed macaques live in southeast Asia, including India, Bangladesh, Myanmar, Thailand, China, Laos, Cambodia, and Vietnam. Southern pig-tailed macaques live in forests, mostly rainforests, and swamps. Northern pig-tailed macaques spend most of their feeding time in the middle canopy, while southern pig-tailed macaques are ground foragers.

Pigtail Macaque Behavior

southern pig-tailed macaque in Sabah, Borneo

Pigtail macaques are arboreal (live mainly in trees), terricolous (living in the ground or in the soil), diurnal (active mainly during the daytime), motile (move around as opposed to being stationary), sedentary (remain in the same area), territorial (defend an area within the home range), social (associates with others of its species; forms social groups), and have dominance hierarchies (ranking systems or pecking orders among members of a long-term social group, where dominance status affects access to resources or mates). [Source: Kayla Ayers and Candace Vanderpoel, Animal Diversity Web (ADW) /=]

Pigtail macaques spend most of their time in the trees, with only 8.4 percent of their time on the ground. Their time in the trees is divided between different canopy levels, with most time spent in the middle canopy (47.4 percent), then the lower canopy (33.8 percent), and finally the upper canopy (10.4 percent).

Pigtail macaques cover long distances while foraging, indicating that they have large home ranges. Their home ranges vary in size from about 0.6 to 8.28 square kilometers (0.232 and 3.20 square miles). In a day of foraging they will travel a linear distance of between .83 and three kilometers. Home ranges usually overlap with other individual and groups and there has been little evidence that they activity defend these areas. However, at a specific time in a specific area, they may drive off other groups of monkeys. Larger groups might also overthrow smaller ones.

Pigtail Macaque Social Behavior

According to Animal Diversity Web: Pigtail macaques live in multi-male, multi-female groups. The females stay with the natal group, making it a female-bonded society. The largest group seen is 81 monkeys. The average group size is between 15 and 40 individuals. When a male is between the ages of five and 6, they leave the natal group and roam independently or try to join another group. If they happen to join another group, they go in as the lowest-ranking male and have to work their way up through competition with the other males. Females also have their own dominance hierarchy, with the highest-ranking females generally being sisters who share this role and are tolerant of one another. They display this by grooming, kissing, and feeding together.[Source: Kayla Ayers and Candace Vanderpoel, Animal Diversity Web (ADW) /=]

Males are socially dominant over females. However, groups of females will band together against a male and attack him. Sometimes females will attack lower-ranking males with the help of their relatives because of competition for food. There is also aggression between higher-ranking males and lower-ranking males. Aggression levels are especially high when solitary males are trying to join a new group.

After agonistic encounters, there are different forms of reconciliation, depending on gender and rank. Females may mount each other after an aggressive encounter. The dominant one will mount the subordinate one. In males it is the opposite. The dominant male will be mounted by the subordinate one, showing the dominant’s tolerance of those lower than himself. Dominant females also have a way of showing their tolerance. This is generally done through the dominant female kissing the subordinate one. The dominant male in a captive environment sometimes takes part in infanticide within the group. This has only been seen in captive pigtail macaques.

Pigtail Macaque Communication

range of the southern pig-tailed macaque

Pigtail macaques sense and communicate with vision, touch, sound and chemicals usually detected by smelling. According to Animal Diversity Web: 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. [Source: Kayla Ayers and Candace Vanderpoel, Animal Diversity Web (ADW) /=]

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. /=\

Pigtail Macaque Feeding, Predators and Ecological Niches

Pigtail macaques are primarily frugivores (eat mainly fruits). Animal foods include nestling birds, termite eggs, larvae, river crabs and other aquatic crustaceans. Among the plant foods they eat are leaves seeds, grains, and nuts. They also eat fungus Pigtail macaques are ground foragers. They divide into small groups of two to six while foraging and keep in contact with other groups through vocalizations. [Source: Animal Diversity Web (ADW)]

They range widely when searching for food. Pigtail macaques are known for raiding the fruit crops of farmers. When they do this they will set up a guard to look for humans and shout a warning signal to those in the fields if a human shows up. Research with captive macaques has shown that pigtail macaques are particularly fond of mango and pineapples. Their least favorite crop food was carrots.

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. 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. Animal predators include leopards, crocodiles and snakes. Pigtail macaques often come in contact with white-handed gibbons (Hylobates lar). The two species compete for resources and are often an annoyance each other.

Pigtail Macaque Reproduction and Offspring

Pigtail macaques are polygynandrous (promiscuous), with both males and females having multiple partners. They engage in year-round breeding. 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 have large purple-pink swelling in their anus and genital areas. The breeding interval is between one year and two years. The number of offspring ranges from one to two, with the average number being one. /=\

Females mate with multiple males during a lifetime and do not discriminate between adolescents and adult males. According to Animal Diversity Web: 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 males and females 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 three 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 gives 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.

The gestation period ranges from 162 to 186 days, with the average being 171 days. Young pigtail macaques are then nursed for eight to 12 months. Pigtail macaques are born with black fur. By the third month of life, their coat starts to change to an olive brown, the color of adults. After one year pigtail macaques are considered adolescents and remain so until they reach reproductive maturity. Females reach sexual or reproductive maturity at three to 3.5 years. Males reach sexual or reproductive maturity at four to 4.5 years. /=\

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.

Pigtail Macaques, Humans and Conservation

In Thailand and Malaysia, pig-tailed macaques are trained to pick coconuts. These macaques can pick more than 1000 coconuts a day. Pigtail macaques are also sought for use in medical research, such as research on HIV. Local populations of humans hunt them for food. Pigtail macaques are pests to farmers because they often raid crops and steal corn and coconuts. [Source: Kayla Ayers and Candace Vanderpoel, Animal Diversity Web (ADW) /=]

Pigtail macaques are classified as vulnerable on the IUCN redlist. With CITES they have no special status. They are mainly threatened by the destruction of their natural habitat. Rubber, palm oil and timber companies cut down trees and small families practice slash and burn agriculture. Sometimes pigtail macaques are killed by locals for food. They are being shot and killed at higher rates in some places, such as Borneo, where there numbers are declining. Another threat to pigtail macaques, especially in India, is the effects of pollution from coal mines.

According to Animal Diversity Web” 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. /=\

Brawling Pig-Tailed Macaques in Thailand

In March 2020, in the middle of the Covid-19 pandemic, Annie Roth wrote in the New York Times: In a video posted last week, a mob of monkeys runs around a city plaza in Thailand. Something gets thrown in the macaques’ midst and they break into a giant brawl. [Source: Annie Roth, New York Times, March 16, 2020]

“This horde of animals lives in Lopburi, home of the country’s Phra Prang Sam Yot monkey temple. The macaques, which are usually fed by tourists visiting the city, are finding a new scarcity because of the coronavirus. And they’re not alone. Large populations of wild animals are sustained almost entirely on treats handed out by tourists in a variety of Asian countries. But over the past few weeks, the flow of tourists has been reduced to a trickle as a result of quarantines, travel restrictions and a general reduction in visitors put in place to stop the spread of the illness.

“Although fights between the macaques of Lopburi are not uncommon, a brawl of the magnitude shown in that video suggests that resources are scarce, said Asmita Sengupta, an ecologist at the Ashoka Trust for Research in Ecology and Environment in Bangalore, India, who studies the effects of humans feeding macaques, which remain wild animals even if they live in close quarters with people. “The fall in tourist numbers because of Covid-19 may have indeed brought about a shortage of food supply for them,” she said. That shows that feeding the monkeys “can have detrimental effects. Once they get used to being fed by humans, they become habituated to humans and even display hyper-aggression if they are not given food.” The number of tourists from China, Thailand’s biggest source of tourists, fell 85 percent last month, according to the Tourism Authority of Thailand. And it isn’t the only country where the steep reduction in visitors could be affecting some wildlife.

This wasn't the first time something like this happened. In November 1998 The Telegraph, reported: “A thousand hungry monkeys have gone on the rampage through houses, shops and restaurants in northern Thailand after the recession-hit district council ran out of funds for their customary food handouts. Villagers have been woken at night by whole families of monkeys turning over their kitchens, while diners have seen their food stolen from their plates. Following a drought, there has been no extra rice for the macaque monkeys, which had grown dependent on regular supplies from villagers. The Rasi Salai council told a delegation of the monkeys' victims that it could not afford to buy extra rice from outside. [Source: Alex Spillius, The Telegraphy Bangkok]

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated December 2024