Stump-Tailed Macaque, Macaca arctoides
STUMP-TAILED MACAQUE
Macaca arctoides
Geographic Distribution and Habitat
The stump-tailed macaque, also known as the bear macaque, is found in multiple South and Southeast Asian countries. These include Cambodia, southern China, northeastern India south of the Brahmaputra River, Laos, Peninsular Malaysia, Myanmar, Thailand, and Vietnam. They are possibly extinct in Bangladesh and have been introduced to Hong Kong. In addition, a study population was introduced to Tanaxpillo, an uninhabited island in Lake Catemaco, Veracruz, Mexico in 1974, where they range in semi-natural conditions.
Within their vast distribution, they range in habitat from tropical semi-evergreen forest to tropical wet evergreen forest, and tropical moist deciduous forest. Deciduous forests lose their leaves during autumn and winter, while evergreen trees keep them year-round. The macaques prefer dense tropical semi-evergreen forests but can live in disturbed secondary forests and those adjoining human-modified habitats. A secondary forest has grown back after a period of human-caused disturbance. Stump-tailed macaques have also been found in lowland semi-evergreen forests and monsoon and montane (mountainous) forests. They live at elevations ranging between 0.03-1.74 miles high (50-2,800 m).
Size, Weight, and Lifespan
Stump-tailed macaques exhibit sexual dimorphism, where there are noticeable physical differences between genders other than those that define their sex. Males are larger than females, with a head and body length measuring 20.4-25.6 inches (51.7-65 cm) long, and weighing 21-22 pounds (9.7-10.2 kg). Females have a head and body length measuring 19.1-23.0 inches (48.5-58.5 cm) long and weigh 17-20 pounds (7.5-9.1 kg).
Their lifespan in the wild is around 20 years.
Appearance
The stump-tailed macaque is aptly named for a few distinguishing features. The body is covered in long, thick, dark brown fur, whereas the face and short tail are hairless. Underneath all of that hair is a large, bulky, muscular build with thick limbs. This build, unique for macaques, makes them very mobile on land, yet quite ungainly in the trees. The face is bright pink or red, which darkens to brown or nearly black as they age and are exposed to sunlight. In another example of sexual dimorphism, males have more elongated canine teeth compared to females and use these teeth as important tools for establishing dominance within social groups. Like all macaques, the stump-tailed macaque also comes equipped with cheek pouches, which they use to store food for short periods of time.
Infants are born white and darken as they mature. As the macaques age, not only do their faces darken, but they also lose hair on their heads in a manner similar to male pattern human baldness in humans!
Diet
The stump-tailed macaque is primarily frugivorous, meaning fruit-eating. However, they also consume many types of vegetation, such as seeds, leaves, roots, and flowers. They are known to hunt for insects and their larvae, frogs, birds and their eggs, and freshwater crabs. Finally, they are opportunists and may raid human crops, with a particular love for corn and other cultivated fruits.
Behavior and Lifestyle
The stump-tailed macaque is both arboreal and terrestrial, spending time up in the trees, and down on the ground. Traveling on all fours wherever they go, they spend more time on the ground, however, their bulky build makes traveling around the trees rather slow and awkward. The species is diurnal, meaning they are most active during daylight hours.
Starting their day at dawn, stump-tailed macaques spend the early morning until midday traveling and feeding. During the middle of the day, the group stops and rests in the shade, spending time on social activities such as grooming, while the juveniles and adolescents play. In the late afternoon, foraging commences yet again as they travel to their sleeping site, which usually consists of large trees or cliffs. Their daily traveling range is between 1.24-1.86 miles (two to three km), but they don’t travel as far during the rainy monsoon season, as food is much more abundant during that time and does not require travel.
Though they spend the majority of the day traveling on the ground, usually along the banks of rivers and streams, stump-tailed macaques also forage for fruit and leaves in trees and flee to trees when in danger. Besides humans, potential predators of stump-tailed macaques include clouded leopards, leopards, dogs, and large raptors. When a predator is nearby, they respond by assuming threatening postures, shaking trees and branches, and baring their canine teeth as a threat.
Meat-loving macaques: The stump-tailed macaque’s unusually muscular and thick physique may be responsible for their unique tendency to consume larger quantities of meat than other macaque species. Despite this, fruit always reigns supreme in their diet!
Male pattern baldness? Yes, but no one is safe!: Stump-tailed macaques go through the same male pattern baldness seen in humans as they age. While that may seem a bit humorous, it’s not just the males that lose the hair on the top of the head. Females lose it, too! At least, here at New England Primate Conservancy, we think bald is beautiful!
A stump is a stump: We’re not kidding when we say their tails are short! The tail of the stump-tailed macaque measures between 1.3-2.7 inches (32-69 mm).
Like other macaques, stump-tailed macaques live in large multi-male multi-female groups consisting of 5-60 individuals. Also like other macaques, female dominance is inherited through the mother’s rank, while for males, dominance fluctuates based on an individual’s fighting ability and social maneuvering. Upon reaching sexual maturity, females stay with their birth group, while males will leave to establish a group of their own.
The home range of a stump-tailed macaque group is unknown but is thought to be several square miles or kilometers.
In terms of relations with other primates, findings from documents based in Thailand indicate that stump-tailed macaques are sympatric (occur in the same area) with long-tailed macaques (M. fascicularis) in Thailand’s Wat Tham Khao Daeng National Park and use the same food resources. They are also known to be sympatric with three other macaque species found in Thailand: the rhesus macaque (M. mulatta), the Assam macaque (M. assamensis), and the northern pig-tailed macaque (M. leonina).
Stump-tailed macaques communicate primarily visually and vocally. Common submissive/appeasement visual signs include “teeth-chattering”, “lip-smacking”, bared teeth, “hindquarter-presentation” and “present-arm,” in which an arm is put directly in front of the face of the dominant individual to be bitten. Vocal sounds include: a “coo” sound to stay in contact with others; screams during instances of conflict or fear, as well as infants in distress; grunts in moments of establishing social bonds and females expressing interest in another female’s infant; “roars” are used by the dominant male(s) to chase off predators.
The species is noted as being particularly “peaceful”, as they have a variety of means to reconcile with group members. Physical violence very rarely occurs, and although minor scraps often flair up in the form of bites and slaps to reinforce rank. Physical intimidation displays do occur, but they tend to quickly be resolved.
Stump-tailed macaques have a low reproductive rate compared to other macaque species, giving birth every two years. Their breeding season occurs during the autumn months of October and November. These “free and easy hippie primates” are promiscuous, meaning both males and females have multiple mates during the breeding season. After a gestation period of around 177 days, females give birth to a single offspring. Mom nurses and protects her infant for nine months, upon which the infant is weaned from her milk. Stump-tailed macaque mothers are considered more “permissive” compared to other macaque species, and early on, they allow infants to independently explore their surroundings. They may be this easygoing because other group members are genuinely interested in the infants, but never treat them roughly or “kidnap” them as is seen in other macaque species.
All females in the group care for the young of other females, a process known as allomothering. They play, carry, protect, and groom the infants, regardless of parentage. This also benefits lower-ranking females, as they may receive more tolerance and less aggression from higher-ranking females. High-ranking males also help protect young from potential danger, but otherwise provide no other fatherly duties.
After weaning, the infant is still dependent on the adults in the group. Juveniles will become independent at around one-and-a-half years of age. Females reach sexual maturity at four years of age, while males become mature at around four-and-a-half to five years of age, but don’t reach adult size until six years of age. Upon reaching maturity, females remain within the group, while males leave to establish a group of their own.
As fruit-eaters, stump-tailed macaques aid in the regeneration of their forest habitats by dispersing seeds through their feces as they move around the habitat. They also play a role in pollination. Like bees and butterflies, they collect pollen from flowers when consuming them. They then deposit the pollen on each subsequent flower they visit, thereby pollinating the plants. In addition, they may serve as pest controllers, since a portion of their diet is made up of insects and their larvae. Finally, as a prey species, they also play a role in feeding local predators within their range.
The International Union for Conservation of Nature lists the stump-tailed macaque as Vulnerable (IUCN, 2020), appearing on the IUCN Red List of Threatened Species.
The primary threats facing the stump-tailed macaque are habitat disturbance and hunting by humans.
Habitat disturbance comes in a variety of methods, including selective logging, timber and firewood collection for charcoal, building roads, dams, power lines, and fisheries, deliberately setting fires, habitat degradation and fragmentation, mining, plantations, and soil loss/erosion.
Stump-tailed macaques are also hunted and traded for food, sport, and traditional “medicine”. They may also be victims of accidental deaths due to trapping for other species. There is local trade for bones, meat for food, and live animals as pets to which they fall prey. They are also hunted in retribution for acting as crop pests in parts of India. Some of the hunting and trading of the stump-tailed macaque is for subsistence among locals, while other hunting motivations include their worth in the trade of exotic species across borders.
The stump-tailed macaque is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival.
Stump-tailed macaques are found in a number of protected areas throughout their range, including:
• India: Nokrek National Park, Balpakram National Park, Kamlang Wildlife Sanctuary, Hollongapar Gibbon Wildlife Sanctuary, Mehao Wildlife Sanctuary, Murlen National Park, and Namdapha Wildlife Sanctuary
• Thailand: Huai Kha Khaeng Wildlife Sanctuary, Thungyai Wildlife Sanctuary, Phu Khieo Wildlife Sanctuary, Khao Krapuk-Khao Tao Mo Wildlife Non-Hunting Area, Khao Sok National Park, and Khao Luang National Park
• Malaysia: Perlis State Park
• Laos: Nam Ha National Biodiversity Conservation Area
Stump-tailed macaques are protected by national wildlife acts in Laos, Vietnam, Thailand, Cambodia, Malaysia, and Myanmar. Regionally, India lists the stump-tailed macaque as Schedule II under the Indian Wildlife (Protection) Act, 1972, amended up to 2002. Their populations in the protected areas in India are also increasing, however, the species is still facing severe threats with few populations left. Their status in India needs revision, so they can receive better protection, and needs revision of their status in India in order to benefit from better protection.
Conservation actions needed include properly enforced land, water, site/area, and resource protection and management, and stronger enforcement of harvest and trade management practices. Further monitoring of the population trends of the stump-tailed macaque, as well as research into their: population size, distribution, and trends; life history and ecology; human harvesting; threats. Also needed are actions aimed at the conservation and protection of the species. This research is especially crucial in their native ranges across Asia, as there have been very few long-term studies of wild stump-tailed macaques, and most information comes from the introduced population on Tanaxpillo, or other captive settings.
In the end, much is needed from humans if the stump-tailed macaque is to have a chance of surviving the plight of endangerment and extinction.
- https://www.alltheworldsprimates.org/Members/Home/MasterPrimate.aspx?tid=428
- https://animalia.bio/stump-tailed-macaque
- https://www.bioexplorer.net/animals/mammals/monkeys/stump-tailed-macaque/
- https://cza.nic.in/uploads/documents/studbooks/english/nsstumtailedmacaque.pdf
- https://en.wikipedia.org/wiki/Stump-tailed_macaque
- https://www.iucnredlist.org/es/species/12548/185202632
- https://primate.wisc.edu/primate-info-net/pin-factsheets/pin-factsheet-stump-tailed-macaque/
- https://roundglasssustain.com/infographics/stump-tailed-macaque-facts
- https://study.com/academy/lesson/stump-tailed-macaque-lifespan-diet-facts.html
Written by Sienna Weinstein, November 2024