Macaca nemestrina

Geographic Range

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 oriental
  • introduced introduced
  • native native

Habitat

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.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• rainforest rainforest

• Wetlands
• swamp swamp

Physical Description

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).

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes shaped differently

Reproduction

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) 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.

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

Lifespan/Longevity

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.

Behavior

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 5 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.

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

• Key Behaviors
• arboreal arboreal
• terricolous
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Home Range

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 km² (0.232 and 3.20 mi²). In a day of foraging they will travel linear distances between 825 and 2964 m. Home ranges usually overlap with other groups and there has been little evidence to suggest that they defend these areas. However, when in a specific area at a specific time, they may drive off other groups of monkeys. Larger groups might also overthrow smaller ones.

Communication and Perception

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 visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

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).

• Primary Diet
• herbivore herbivore
  • frugivore frugivore

• Animal Foods
• birds
• insects
• aquatic crustaceans

• Plant Foods
• leaves
• seeds, grains, and nuts

• Other Foods
• fungus

Predation

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).

Ecosystem Roles

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

Economic Importance for Humans: Positive

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 food
• source of medicine or drug source of medicine or drug
• research and education

Economic Importance for Humans: Negative

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

Conservation Status

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.

Additional Links

Encyclopedia of Life

Contributors

Kayla Ayers (author), James Madison University, Candace Vanderpoel (author), James Madison University, Suzanne Baker (editor, instructor), James Madison University, Tanya Dewey (editor), Animal Diversity Web.

References

Carey, J., D. Judge. 2002. "Max Planck Institute for Demographic Research" (On-line). Longevity Records Life Spans of Mammals, Birds, Amphibians, Reptiles, and Fish. Accessed April 29, 2009 at http://www.demogr.mpg.de/longevityrecords/0203.htm .

Cawthon Lang, K. 2009. "Primate Info Net: Library and Information Service: National Primate Research Center, University of Wisconsin- Madison" (On-line). Primate Factsheets: Pigtail macaque (Macaca nemestrina) Taxonomy, Morphology, & Ecology Taxonomy, Morphology, & Ecology. Accessed March 20, 2009 at http://pin.primate.wisc.edu/factsheets/entry/pigtail_macaque/taxon .

Kim, J., M. Kim. 2003. A histologic demonstration of siliceous materials in simian lung mite infected lung tissues by microincineration. Journal of veterinary science , 4/2: 117-123.

Laska, M. 2001. A comparison of food preferences and nutrient composition in captive squirrel monkeys, Saimiri sciureus, and pigtail macaques, Macaca nemestrina. Physiology & Behavior , 73/1-2: 111-120.

Nowak, R. 1999. Walker's Primates of the World . Baltimore, Maryland: Johns Hopkins University Press.

Plesker, R., C. Bauer, K. Tackmann, A. Dinkel. 2001. Hydatid Echinococcosis (Echinococcus granulosus) in a Laboratory Colony of Pig-Tailed Macaques (Macaca nemestrina). Journal of veterinary medicine , 48/5: 367-372.

Rollins, A., K. Snook, P. Dorn, M. McNeese, R. Lundquist, F. Cogswell. 2008. Parasite survey of guinea baboons, rhesus macaques, and pigtail macaues in a an outdoor breeding colony in Louisiana: implications for paleoparasitology. American Journal of Anthropology, Supplement: Program of the Seventy-seventh Annual Meeting of the American Assoiciation of Physical Anthropologies , 135/S46: 182.

Rowe, N. 1996. Pictorial Guide to the Living Primates . East Hampton, NY: Pogonias Press.

Steinmetz, R., W. Chutipong, N. Seuaturien. 2006. Conservation in Practice: Collaborating to Conserve Large Mammals in Southeast Asia. Conservation Biology , 20/5: 1391-1401.

Whitington, C. 1992. Interactions between lar gibbons and pig-tailed macaques at fruit sources. American Journal of Primatology , 26/1: 61-64.

Wildscreen. 2003. "ARKive: Images of Life on Earth" (On-line). Sunda pig-tailed macaque (Macaca nemestrina). Accessed April 02, 2009 at http://www.arkive.org/sunda-pig-tailed-macaque/macaca-nemestrina/image-G9683.html .