LANGURS OF INDONESIA: SPECIES, CHARACTERISTICS, BEHAVIOR

LANGURS

surili in Sumatra

Langurs are mostly leaf-eating, tree-residing, forest-dwelling monkeys. They are regarded as among the most arboreal of all Old World monkeys. They are active throughout the tree canopy and can be found in both primary and secondary forests. They rarely come to the ground. When they do it is mainly to gain access to mineral sources.

Most langurs are grayish, brownish or blackish, with paler underparts. Some have light colored markings on their head or stripes on their thighs. Langur adults weigh from five to eight kilograms and have a head and body length of 42 to 61 centimeters (16.5 to 24 inches) and a tail length of 50 to 85 centimeters (20 to 33.5 inches) .

Langur bodies are adapted for tree life. They have long tails, a slender body, strong slender hands, and well developed fingers. Although langurs eat leaves the their primary sources of nutrition come from fruits and seeds. On a daily basis they range through the forest between 500 and 800 meters to forage.

Websites and Resources: Animal Diversity Web animaldiversity.org ; BBC Earth bbcearth.com; A-Z-Animals.com a-z-animals.com; Live Science Animals livescience.com; Animal Info animalinfo.org ; World Wildlife Fund (WWF) worldwildlife.org the world’s largest independent conservation body; National Geographic National Geographic ; Endangered Animals (IUCN Red List of Threatened Species) iucnredlist.org

Presbytis Genus Langurs of Sumatra, Borneo, Java and Malaysia

Presbytis is a genus of Old World monkeys also known as langurs, leaf monkeys, or surilis native to Sumatra, Borneo, Java and smaller nearby islands in Indonesia and the the Thai-Malay Peninsula. They are smallish, slimly built primates. Their fur at the top is brown, grey, black, or orange, and at the lower surface whitish or greyish, sometimes also orange, with some species having fur designs at the head or at the hips. Their German name of Mützenlanguren ("capped langurs") comes from the hair on their head, which forms a tuft. Surilis range in adult length from 40 to 60 centimeters (with a 50- to 85-centimeter-long tail) and a weight of five to eight kilograms. [Source: Wikipedia]

Langurs of the Presbytis Genus differ from the other langurs: 1) in head shape (particularly the poorly developed or absent brow ridges, and the prominent nasal bones), 2) in the teeth, and 3) by the size of their small thumbs. Two other genera, Trachypithecus and Semnopithecus, were formerly considered subgenera of Presbytis. The species-level taxonomy of Presbytis is complex, and significant changes have been proposed for several in recent years.

Diurnal forest dwellers, Langurs of the Presbytis Genus mainly eat leaves, fruits, and seeds and spend nearly their entire lives in the trees. They live in groups of up to 21 animals (typically 10 or fewer animals in most species) consisting of a male, several females, and their young. A few species have been observed in monogamous pairs. Lone males and all-male groups have also been observed. The groups have a hierarchical arrangement, with intergroup communication that is both vocal and postural. Their gestation period is five to six 5–6 months, producing a single offspring. Newborns are white colored and have a black strip at the back, although some have a cross-shaped mark. By one year old, the young are weaned and at an age of 4–5 years, they are fully mature. The typical life expectancy in the wild remains poorly known for most species, but captive Sumatran surilis have lived more than 18 years.

Langurs and Leaf Monkeys of Indonesia

East Javan langur

Natuna Island surili (Presbytis natunae, Thomas & Hartert, 1894) live on the island of Natuna Besar in Indonesia. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch) tail. They live in the forest and eat fruit, seeds, and leaves. They are critically vulnerable. There are 9,000 of them. Their population is declining.

East Javan Langurs (Trachypithecus auratus, É. Geoffroy, 1812) are brown in color. They live in Java and nearby islands in Indonesia. They are 44–65 centimeters (17–26 inches) long, with a 61–87 centimeter (24–34 inch) tail. They live in the forest and eat leaves and flowers, as well as fruit and insect larvae. They are vulnerable. Their numbers are unknown.Their population is declining.

West Javan Langurs (Trachypithecus mauritius, Griffith, 1821) are gray monkeys. They live in Island of Java. They are 40–76 centimeters (16–30 inches) long, with a 57–110 centimeter (22–43 inch) tail. They live and eat leaves, flowers, and fruit. They are vulnerable. Their numbers are unknown. Their population is declining.

Javan surili (Presbytis comata, Desmarest, 1822) are gray in color. There are Two subspecies: 1) P. c. comata; and 2) P. c. fredericae. They live on Java in Indonesia. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch) tail. They live in the forest and eat leaves,, as well as fruits, flowers, and seeds. They are critically vulnerable. 5,500 Their population is declining.

Javan Langurs

Javan langurs (Trachypithecus auratus) live on the Indonesian islands of Java, Bali and the Lombok. They can be found in inland forests, on the coast and on edges of rainforests. They have been seen in the primary and secondary forests in the Dieng Mountains of central Java as well as a variety of forest types — mangrove, beach, freshwater swamp, lowland and hill forest, deciduous forest, and mountain forest up to 3500 meters (11483 feet). In Indonesia they are sometimes called Hanuman langur. This name also describes of a langur of a different species in India. Hanuman is the Hindu monkey god.[Source: William Cannon and Abby Vos, Animal Diversity Web (ADW) /=]

The average weight of Javan langurs is seven kilograms (15.4 pounds). Their head and body length ranges from 44 to 65 centimeters (17.3 to 25.6 inches), plus a tail that is 61 to 87 centimeters (24 to 34 inches) long. They move quadrupedally (using all four limbs for walking and running) and have enlarged salivary glands and a dental formula of 2:1:2:3. Javan langurs also have sacculated stomachs that assist in breaking down plant materials. Sexual Dimorphism (differences between males and females) is present: Female coloration is slightly different; they have yellow pubic patches. The average lifespan of these animals in the wild is 20 years.

East Javan langurs at the Bronx Zoo

Two species (subspecies) of Javan langurs are described: 1) the western Javan langur (or western Javan ebony langur, Trachypithecus auratus mauritius); and 2) the eastern Javan langurs (or spangled ebony langurs, Trachypithecus auratus auratus). There is some debated whether or not they are species or subspecies. Roos et al., 2008, elevated T. a. mauritius to a separate species as Trachypithecus mauritius based in part on genetic studies Both subspecies have glossy black coats with brown on the legs and belly. Sometimes, individual Javan langurs auratus have orange coats. Orange color morphs are found in a restricted portion of the distribution of eastern Javan langurs. Javan langur infants are born with orange coats and the coats get darker as they age.

Javan langurs are primarily folivores (eat mainly leaves) but can also be described as herbivores (primarily eat plants or plants parts) and frugivores (eating fruit). They mostly eat leaves and flowers. Their enlarged salivary glands and sacculated stomachs are well adapted for this plant diet. They also eat fruit, ripe and unripe, and insect larvae. The diet consists of 15 to 27 percent unripe fruit and 10 to 12 percent ripe fruit. They may eat fruits mainly to get at the seeds. Javan langurs prefer leaves rich in protein content and low in fiber. Different groups will feed at the same food source without significant aggression. Adult males do not proportionally feed as often as other group members, females and the young.

Javan langurs are not endangered. On the International Union for Conservation of Nature (IUCN) Red List they are listed as Vulnerable. In CITES (Convention on International Trade in Endangered Species of Wild) they have no special status. However, populations are decreasing due to human activities, such as habitat loss resulting from agricultural expansion, hunting, and the illegal pet trade. Anti-predator vocalizations adapted to humans include a shrill alarm call when a human is sighted. Laws protecting Javan langurs in Indonesia were passed in 1999. These langurs are found in three Indonesian national parks: Gunung Halimun, Pangandaran, and Ujung Kulon. Their main natural predators are Javan leopards. In the past they were preyed on by now extinct Javan tigers.

Javan Langur Behavior, Communication and Reproduction

Javan langurs are arboreal (live mainly in trees), scansorial (able to or good at climbing), terricolous (live on the ground), diurnal (active 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). Their home range is estimated to be 20 to 30 hectares and may be larger on Java than on other islands. Javan langurs have a population density of 23 individuals per square kilometer in the Dieng Mountains of Java. [Source: William Cannon and Abby Vos, Animal Diversity Web (ADW) /=]

According to Animal Diversity Web: Researchers found that when offered food from tourists, these langurs do not accept it. Individuals will often take turns and feed while others in the group are resting or traveling. They live in groups of approximately seven members with one to two males and five to six females. However, groups can exist with up to 21 members, still with only one to two males. Group size varies depending on climate conditions. Groups inhabiting habitats with a longer dry season tend to be larger than other groups. Females make up the majority of the group because of male competition and the polygamous mating system. Males disperse from their natal group and may travel alone, or can band together with other bachelor males. The dominant male keeps a close relationship with all females within the group. Females care for and protect their young, as well as the offspring of their fellow female group members. Females are aggressive toward females from other groups. /=\

Distribution of Selangor Silvered Langurs (red), Silvery lutungs (green), West Javan langurs (blue) and East Javan langurs (yellow)

Javan langurs communicate with vision, touch and sound and sense using vision, touch, sound and chemicals usually detected with smell. They use alarm calls that sound like "ghek-ghok-ghek-ghok." They also communicate through visual cues and touch. Infants are brightly colored and females will look after and protect infants of other females. It has been hypothesized that females behave in this manner because the bright orange color of the infants signals that they need to be cared for. Allogrooming is an important way to cement social bonds. Aggression is communicated with physical interactions, vocalizations, and visual cues, all of which establish social rank. Research on chemical communication by Javan langurs has been lacking.

Javan langurs are polygynous (males have more than one female as a mate at one time). They are also cooperative breeders (helpers provide assistance in raising young that are not their own). These monkeys engage in year-round breeding, with the average number of offspring being one Javan langurs have one to two males in each group, which has a large effect on the group's mating behavior. There is virtually no within-group competition among males, ensuring that they are successful in mating. Males in the group father all offspring. Females in social groups cooperate to care for all young in the group.

Female Javan langurs typically begin to breed around three to four years of age. The and the average time to independence is 12 months. Females are the primary caregiverMothers in the group all care for each others' young, in a practice called "allomothering." The vibrant color of young Javan langurs may make it easier for mothers to keep an eye on them and ensure they stay out of trouble.

Langurs on Sumatra

Black Sumatran langur (Presbytis sumatrana, S. Müller & Schlegel, 1841) live on the island of Sumatra in Indonesia. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeters (20–33 inch) tail. They live in the forest and eat fruit, leaves, seeds and flowers. They are endangered. Their numbers are unknown. Their population is declining.

Black-and-white langurs (Presbytis bicolor, Aimi & Bakar, 1992) live on the island of Sumatra. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch) tail. They live in the forest and eat fruit, seeds, and leaves. Their numbers are unknown.

Black-crested Sumatran langurs (Presbytis melalophos, Raffles, 1821) are gray and brown in color. They live on the island of Sumatra. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch)tail. They live in the forest and shrubland and eat fruits and leaves, as well as seeds and flowers. They are endangered. Their numbers are unknown. Their population is declining.

East Sumatran banded langurs (Presbytis percura, Lyon, 1908) live on the island of Sumatra. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch) tail. They live in the forest and eat fruit, seeds, and leaves. They are critically endangered. Their numbers are unknown. Their population is declining.

Mitered langurs (Presbytis mitrata, Eschscholtz, 1821) live on the island of Sumatra. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch) tail. They live in the forest and eat fruit, seeds, and leaves. They are critically vulnerable. Their numbers are unknown. Their population is declining.

Thomas's langurs (Presbytis thomasi, Collett, 1893) are gray in color. They live in Sumatra in Indonesia. They are 42–62 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch) tail. They live in the forest and eat fruit, leaves, and seeds, as well as flowers, bark, twigs, stalks, birds, bird eggs, algae, and insects. They are critically vulnerable. Their numbers are unknown. Their population is declining.

Thomas’s Langur

East Javan langur

Thomas’s langurs (Presbytis thomasi) are also known as the North Sumatran leaf monkey or Thomas's leaf monkey. They live in North Sumatra of Indonesia north of Sungai Wampu and Sungai Simpang Kiri mostly in tropical rainforests, rubber plantations, and primary and secondary forests. They spend most of their time in trees — exactly where depends on what time of day it is. When they nap during the day, they seek out trees with lots of twigs and leaves for protection from the harsh sunlight. When sleeping at night, they sleeps in the top of tall trees that face the open areas. Their average lifespan in the wild is 20 years. Their average lifespan in captivity is 29 years. [Source: Mika Matthews, Animal Diversity Web (ADW) /=]

Thomas’s langurs range in weight from five to 8.1 kilograms (11 to 17.8 pounds) and range in length from 92 to 147 centimeters (36.2 to 59 inches). The tail length is between 50 and 85 centimeters, (20 and 33.5 inches) and the head and body length ranges between a mere 42 and 62 centimeters (16.5 and 24.4inches). Sexual Dimorphism (differences between males and females) is not present: Both sexes are roughly equal in size and look similar. The average weight for an adult female is 6.69 kilograms; for an adult male it is 6.67 kilograms.

Thomas’s langurs have a very distinct appearance. They have white fur on their underside and arms which contrasts with the black fur surrounding the rest of the body. The white fur continues up around the neck. Two other white stripes, starting from the top of the head, run down the sides, come together in a V-shape at the eyes and encircle them. A purple-silver colored inner layer forms rings around the orange-brown eyes. Pinkish skin covers the muzzle. /=\

Thomas’s langurs are herbivores (eat plants or plants parts), folivores (eat leaves) and frugivores (eat fruits) and granivores (eats seeds and grain). Animal foods include birds’ eggs, insects, mollusks. Among the plant foods they eat are flowers, bark, twigs, stalks of coconuts, leaf stalks and algae. Water is made available in tree holes. Occasional visits to the ground are made in order to obtain ants, mushrooms, soil minerals, and snails. Peak foraging occurs three times per day, followed by resting in the lower portions of trees.

On the International Union for Conservation of Nature (IUCN) Red List Thomas’s langurs are listed as Vulnerable. In CITES (Convention on International Trade in Endangered Species of Wild) they are in Appendix II, which lists species not necessarily threatened with extinction now but that may become so unless trade is closely controlled. They are regarded as crop pests and may be killed by humans for that reason but their biggest threat comes from the destruction of forests in Sumatra. Natural predators include reticulated pythons, clouded leopards, tigers, and golden cats which good at climbing. These predators however are more effective when attacking Thomas’s langur on the ground. For this reason the most dangerous area for these monkeys is in the lower strata of the forest up to 10 meters. /=\

Thomas’s Langur Behavior and Communication

Thomas’s langurs are arboreal (live mainly in trees), scansorial (able to or good at climbing), diurnal (active during the daytime), motile (move around as opposed to being stationary), nomadic (move from place to place, generally within a well-defined range), 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). The size of their range territory is 500 to 800 square meters. Groups migrate to different areas within the forests. They very territorial, defending its area by barking or even attacking outsiders. [Source: Mika Matthews, Animal Diversity Web (ADW) /=]

Thomas’s Langur

According to Animal Diversity Web: These langurs spend most of the day in groups either resting, feeding, or moving. These groups usually consist of five females and one male, but there can also be small groups of males or individual males living alone. Within these groups, there is a dominance hierarchy that everyone, both male and female, is subjected to. It has been suggested that an individual’s rank within the hierarchy may depend upon its age or its ability to defend itself against others in the group. Even though this langur is known for having a calmer demeanor in gestures and responses to conspecifics than other primates, competition has been observed within groups. Competition increases with the size of the group, and femlaes show a preference for smaller groups due to the decrease in risk of infanticide. Group sizes are often dependent upon female dispersal. Many factors impact a female’s decision to leave her group and join another. These include competition for food, the risk of predation, and avoidance of inbreeding. More important is the avoidance of infanticide. Often a female leaves her group to protect her young from infanticide.

Thomas’s langurs sense and communicate using vision, touch, sound and chemicals usually detected with smell. They also employ choruses (joint displays, usually with sounds). Vocal communication is at its most intense and frequent at dawn. It is utilized in a variety of situations such as relocation, attacking, establishing sleeping positions, defending territory and mates. Vocalizations are accompanied by olfactory communication when mating is intitiated. Thomas' langurs use numerous types of vocal calls. For example, an alpha male tends to make a series of “choom” sounds when he is excited; however, when he is involved in an inter-troop or group-troop encounter, he makes a series of “kak” and “ngkung” sounds. Similarly, when threatened, juveniles make an alternating series of “kek”s and “wek”s. Aggressive females make “kuk” sounds. /=\

Vocal and visual communication develop as these monkeys mature. In infant Thomas’s langur, communication is restricted to whining and squealing. Once an individual becomes a juvenile, its abilities have broadened to screaming, grimacing, slapping the ground, present, alarm barking, staring, and threat bobbing. Finally, as an adult, it no longer squeals or screams, but barks and partakes in dominance fighting. /=\

Thomas’s Langur Reproduction, Offspring and Infanticide

Thomas’s langurs engage in year-round breeding, which can occur every 1.5 to two years. The usual number of offspring is one. The mating system of Thomas’s langur is debated. The Encyclopedia of Mammals describes them as a monogamous primate. The female initiates the mating by performing various acts to persuade her male counterpart, such as releasing certain smells and displaying genitalia. Steenbeck, et al. (1999) dispute the monogamy of the species, saying that within groups, there are often several females and one breeding male. A possible resolution between the two observations is that only one of the females in the group breeds with the male while the other females help raise the young.

The gestation period lasts five to six months. Weaning occurs at 12 to 15 months. After that offspring are supposed to become independent, reaching sexual maturity at four or five years of age. When caring for her young, the mother removes herself from the dominance structure. Other females of the group are often attracted to the young due to the distinct coloring, and so they care for and protect the young whenever possible. As soon as the infant becomes upset or distraught, another female quickly tries to comfort it.. During pre-weaning, the young has to learn what to eat, what to avoid, and other behavioral tactics in order to survive. /=\

The male infant has no contact with a male adult until he is 10 months old. A female infant, however, has no contact with an adult male until she is 3.5 to four years old. Often during weaning, a male within the group or an outside group commits infanticide, killing an infant so that the mother can regain her normal cycle of fertility faster than she would if her child were still alive. This may explain the delay in contact between young and adult males. /=\

Infanticide appears to be a very important behavior for Thomas’s langur. Infanticide usually occurs when males attack. Females do not typically attack unless defending their young from outside males. Females are much more aggressive when they have an infant than they are when they have no dependent offspring. When the group male is within five meters of a mother and her child, she is significantly less vigilant, apparently because the presence of the male so close by is an assurance of protection. /=\

Langurs of the Island Near Sumatra

Siberut langurs (Presbytis siberu, Chasen & Kloss, 1928) are gray in color. They live on the live on the island of Siberut in Indonesia. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch) tail. They live in the forest and eat fruit, seeds, and leaves. They are endangered. Their numbers are unknown. Their population is declining.

Mentawai langurs (Presbytis potenziani, Bonaparte, 1856) live on Mentawai islands in Indonesia. They are 42–61 centimeters (17–24 inches) long, with a 50–85 centimeter (20–33 inch) tail. They live in the forest and eat fruit, seeds, and leaves. They are critically endangered. Their numbers are unknown. Their population is declining.

Pig-Tailed Langurs

pig-tailed langur

Pig-tailed langurs (Simias concolor) are also known as simakobou. They are presently found only on the Mentawai Islands off the west coast of Sumatra in Indonesia and has been eliminated entirely from some islands due to logging and hunting by humans. These primateslive in tropical areas in rainforests, including hillsides with primary forests, and may also resides in swamps and mangrove forests. They are almost entirely arboreal (living in trees), and only comes down from the trees when the forest is disturbed. This species was previously recognized under the name Nasalis concolor. No information is available regarding their lifespan but its relative N. larvatus lives at least 23 years in captivity. [Source: Lyndsay Rankin, Animal Diversity Web (ADW) /=]

Pig-tailed langurs range in weight from 7.1 to 8.7 kilograms (15.6 to 19.2 pounds). Their head and body length ranges from 46 to 55 centimeters (18 to 21.6 inches). Their tail is relatively short — 14 and 15 centimeters (5.5 to 6 inches) — compared to other langurs. Sexual Dimorphism (differences between males and females) is present: Both sexes look similar but males are slightly larger in size, with the body and head length of males ranging from 49 to 55 centimeters; and that of females ranging from 46 to 55 centimeters. The average weight for makes is around 8.7 kilograms; for females it is 7.1 kilograms.

The are two color variations found among pig-tailed langurs: 1) a dark gray phase and 2) a creamy buff type, with the former being more common. The creamy buff type is found in roughly one in four individuals. The of limbs of pig-tailed langurs are of equal length. The tail is hairless, except for a small amount of hair at the tail tip — like a pig. Adult pig-tailed langurs have black faces and small snub-noses. The coat of the dark type is blackish-brown with light speckled hair on the nape, shoulder, and upper back.

Pig-tailed langurs are herbivores (eat plants or plants parts), folivores (eat leaves), frugivores (eat fruit). They eat leaves, fruit, flowers and berries. Feeding occurs after sunrise near the trees used for sleeping and again in the afternoon. Adult males lead the foraging and the females and young follow behind. Possible natural predators include crested serpent eagles and pythons.

On the International Union for Conservation of Nature (IUCN) Red List pig-tailed langurs are listed as Critically Endangered. On the US Federal List they are classified as Endangered. In CITES (Convention on International Trade in Endangered Species of Wild) they are in Appendix I, which lists species that are the most endangered among CITES-listed animals and plants. /=\ The population consists of fewer than 10,000 individuals. Habitat loss due to logging is the main cause of population decline. Hunting is also a major problem, especially in the Pagai Islands, where pig-tailed langur meat is considered a delicacy. This species receives protection at the Teiteibatti Wildlife Reserve, located on the only island that provides such security. It is believed that the population size of pig-tailed langurs decreased by 50 percent in the 1990s and 2000s.

Pig-Tailed Langur Behavior, Communication and Reproduction

Pig-tailed langurs are arboreal (live in trees), diurnal (active 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) and social (associates with others of its species; forms social groups). The average size of Pig-tailed langur territory is between 6.5 to 20 hectares (16.3 and 50 acres). According to Animal Diversity Web: Individuals are not observed deep inside other territories, but are seen on the margin of adjacent territories. During encounters with other groups, the males approach, make loud vocalizations and return to their home territory with the other group members following behind. Chasing and fighting are generally not observed during these encounters. [Source: Lyndsay Rankin, Animal Diversity Web (ADW) /=]

Little is known about the behavior of Pig-tailed langurs because there are so few in such a limited geographical range as well as the difficulty in spotting them in their dense forest habitat. There are two distinct group types exhibited in Pig-tailed langur, family groups and groups of all males; each exhibit unique behaviors. The most common type of grouping is the family group of one male and up to four females. These groups can be formed with a single adult couple and their young or with more than one adult female with a single male. Family group members maintain very close proximity, rarely traveling more than five meters (16 ft.) away from one another. They also restrict vocal communication, only using it at designating group boundaries and as a warning to predators. The all male groups exhibit behaviors that produce excessive noise as they travel through the forest, communicate with others, and leap in displays of strength.

Pig-tailed langurs sense and communicate with vision, touch, sound and chemicals usually detected by smelling. Communication between individuals and groups of Pig-tailed langur is achieved by producing loud calls in a series of vocalizations ranging from two to 25 nasal barks. These barks can travel at least 500 meters through the rainforest. The purpose of these calls is believed to be to maintain group structure and boundaries. Males call out with loud nasal barks and females reply with sharp squeals. It is also likely that chemical cues are used widely in communicating reproductive state and that vision and touch are important.

Pig-tailed langurs are polygynous (males having more than one female as a mate at one time). They engage in seasonal breeding, with the average number of offspring being one. Little data exists regarding the reproductive activity of pig-tailed langur, but it is believed that they mainly give birth June and July. This species also exhibits sexual swelling, a trait that is rare in other Asian colobines. Males have been observed participating in displays of strength that consist of leaping through the trees to attract mates. The social group of Pig-tailed langur includes one male and up to four females with which the male mates.

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