Nilgiri Langur
Semnopithecus johnii
formerly Trachypithecus johnii
Geographic Distribution and Habitat
The Nilgiri langur, also known as the hooded leaf monkey, is a species of Old World monkey endemic to South India. It is found in the Western Ghats, particularly in the Nilgiri Hills from which it derives its name, but also in other hilly areas in that region. They prefer to live between 980 and 6,500 ft (300–2,000 m) above sea level, and typically settle in at around 4,600 ft (1,400 m). Since they are an arboreal species, they seek out habitat with trees, and are known to inhabit secondary moist deciduous forests and evergreen forests. Other considerations include proximity to water and distance from humans.
The Nilgiri langur has a contested taxonomical classification: some believe, based on such qualities as its coloration and cranial morphology, that this species is closely related to the purple-faced langurs of the group Trachypithecus. Contrarily, DNA testing reveals the Nilgiri langur to have a more likely relation to the gray langur, which would place them within the genus Semnopithecus. Some even argue the species warrants its own genus, Kasi. Resultantly, in scientific literature, you might find this species referred to as any of the following: Trachypithecus johnii, Semnopithecus johnii, Presbytis johnii, and Kasi johnii.
The two most often seen are Trachypithecus and Semnopithecus. The International Union for Conservation of Nature (IUCN) still lists the species as Trachypithecus johnii, as it was first dubbed in 1829; and where Semnopithecus johnii is used, it is often with the disclaimer that the species was formerly known as Trachypithecus johnii. Due to it being the original classification, Trachypithecus johnii seems to be the most commonly used name.
The Nilgiri langur, also known as the hooded leaf monkey, is a species of Old World monkey endemic to South India. It is found in the Western Ghats, particularly in the Nilgiri Hills from which it derives its name, but also in other hilly areas in that region. They prefer to live between 980 and 6,500 ft (300–2,000 m) above sea level, and typically settle in at around 4,600 ft (1,400 m). Since they are an arboreal species, they seek out habitat with trees, and are known to inhabit secondary moist deciduous forests and evergreen forests. Other considerations include proximity to water and distance from humans.
The Nilgiri langur has a contested taxonomical classification: some believe, based on such qualities as its coloration and cranial morphology, that this species is closely related to the purple-faced langurs of the group Trachypithecus. Contrarily, DNA testing reveals the Nilgiri langur to have a more likely relation to the gray langur, which would place them within the genus Semnopithecus. Some even argue the species warrants its own genus, Kasi. Resultantly, in scientific literature, you might find this species referred to as any of the following: Trachypithecus johnii, Semnopithecus johnii, Presbytis johnii, and Kasi johnii.
The two most often seen are Trachypithecus and Semnopithecus. The International Union for Conservation of Nature (IUCN) still lists the species as Trachypithecus johnii, as it was first dubbed in 1829; and where Semnopithecus johnii is used, it is often with the disclaimer that the species was formerly known as Trachypithecus johnii. Due to it being the original classification, Trachypithecus johnii seems to be the most commonly used name.
Niligri langur geographic range. Map credit: Chermundy & IUCN
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Size, Weight, and Lifespan
Adult male Nilgiri langurs are larger than females at a ratio of 1.2 to 1. Typically this species measures between 19 and 27 in (49–71 cm) from their head to the base of their tail; their long tails are anywhere from 27 to 38 in (69–97 cm) long. They can weigh anywhere from 22 to 30 lb (10–14 kg). Little is known about the Nilgiri langur’s lifespan, but they have reached the age of 29 years in captivity.
Adult male Nilgiri langurs are larger than females at a ratio of 1.2 to 1. Typically this species measures between 19 and 27 in (49–71 cm) from their head to the base of their tail; their long tails are anywhere from 27 to 38 in (69–97 cm) long. They can weigh anywhere from 22 to 30 lb (10–14 kg). Little is known about the Nilgiri langur’s lifespan, but they have reached the age of 29 years in captivity.
Appearance
With thick black fur and a flaxen, sometimes reddish mane around their black, hairless faces, the Nilgiri langur is a very comely primate. Females, unlike males, have patches of white fur on their thighs. Both males and females have big, dark eyes, providing a striking contrast to their large, white teeth. They have exceptionally long tails. It takes ten weeks before infants bloom into their adult pelage. Their coloration is similar to the lion-tailed macaque, also endemic to the Western Ghats, to which the Nilgiri langur is often compared.
With thick black fur and a flaxen, sometimes reddish mane around their black, hairless faces, the Nilgiri langur is a very comely primate. Females, unlike males, have patches of white fur on their thighs. Both males and females have big, dark eyes, providing a striking contrast to their large, white teeth. They have exceptionally long tails. It takes ten weeks before infants bloom into their adult pelage. Their coloration is similar to the lion-tailed macaque, also endemic to the Western Ghats, to which the Nilgiri langur is often compared.
Photo credit: N.A. Naseer/Creative Commons
Diet
Being folivores, Nilgiri langurs mainly eat leaves. They do not shy away from other sources of sustenance, though, and are known to eat nuts, fruit, seeds, and flowers. Occasionally they are lignivorous, and eat tree bark. Like many folivorous primates, this species will also occasionally eat insects, but that remains an insignificant portion of their diet.
Being folivores, Nilgiri langurs mainly eat leaves. They do not shy away from other sources of sustenance, though, and are known to eat nuts, fruit, seeds, and flowers. Occasionally they are lignivorous, and eat tree bark. Like many folivorous primates, this species will also occasionally eat insects, but that remains an insignificant portion of their diet.
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Behavior and Lifestyle
Nilgiri langurs are a social species and often engage in activities such as grooming and playing within their groups. Playing can often be an expression of dominance, or a form of aggression. Males and females express dominance in different ways: males do this by deciding which sites they travel to, and when; females with a higher position within the group typically show their status by claiming preferred spots for resting or feeding. Higher-ranked males also have more social mobility, and are permitted to interact with all other members of the group, while lower-ranked individuals are not granted this same ability. The adult male is also the chief defender of the group’s territory when they come into contact with other groups. Mostly these interactions are contained to physical and verbal altercations, but can sometimes escalate to one dominant male usurping another dominant male, taking over his group, and killing his offspring. |
Fun FactsNilgiri langurs eat soil. Scientists believe it serves as an antacid, and aids in digestion. |
Daily Life and Group Dynamics
This is a diurnal species, meaning they are active during the day. While active, they spend approximately half of their time eating and the other half resting.
Groups are typically female-centric, but have varying structures. Sometimes there is only one male, other times there are many—but there are always a high number of females. Groups can be anywhere from 1 to 27 in size, but most often fall somewhere in the middle of that range. Since there is a hierarchy within the group, this dominates the way interactions play out between individuals. The higher up an individual is in the hierarchy, the more often he or she will display dominant behavior. Low-ranking members, contrarily, might only rarely get the opportunity to assert themselves over other members of the group.
This is a diurnal species, meaning they are active during the day. While active, they spend approximately half of their time eating and the other half resting.
Groups are typically female-centric, but have varying structures. Sometimes there is only one male, other times there are many—but there are always a high number of females. Groups can be anywhere from 1 to 27 in size, but most often fall somewhere in the middle of that range. Since there is a hierarchy within the group, this dominates the way interactions play out between individuals. The higher up an individual is in the hierarchy, the more often he or she will display dominant behavior. Low-ranking members, contrarily, might only rarely get the opportunity to assert themselves over other members of the group.
Photo credit: Bharath Sambasivam/Creative Commons
Communication
The sounds made by the Nilgiri langur are often described as barks, and they are a highly vocal species. They are most vocal when expressing dominance or subservience within their social groups, or when establishing territorial boundaries with neighboring groups. Within the group, verbal altercations are typically started between females, and the high-ranking males ultimately intervene.
Beyond sounds, they use gestures and facial expressions. An open mouth, for example, is a threat used mostly within the social group.
The sounds made by the Nilgiri langur are often described as barks, and they are a highly vocal species. They are most vocal when expressing dominance or subservience within their social groups, or when establishing territorial boundaries with neighboring groups. Within the group, verbal altercations are typically started between females, and the high-ranking males ultimately intervene.
Beyond sounds, they use gestures and facial expressions. An open mouth, for example, is a threat used mostly within the social group.
Reproduction and Family
The Nilgiri langur reaches sexual maturity at between three and five years of age. The gestation period for this species is between 140 and 220 days, similar to the Hanuman langur, and most babies are born in the months of May and November. This is a result of increased breeding during times where food is more abundant, but this species breeds year round. Babies are born one at a time. Infants are nursed for a year, but mothers are less doting than other species. Mothers also will, eventually, allow other females in the group to interact with their offspring, but it is rare for the infant to be nurtured at all by sexually mature males.
The Nilgiri langur reaches sexual maturity at between three and five years of age. The gestation period for this species is between 140 and 220 days, similar to the Hanuman langur, and most babies are born in the months of May and November. This is a result of increased breeding during times where food is more abundant, but this species breeds year round. Babies are born one at a time. Infants are nursed for a year, but mothers are less doting than other species. Mothers also will, eventually, allow other females in the group to interact with their offspring, but it is rare for the infant to be nurtured at all by sexually mature males.
Photo credit: T.R. Shankar Raman/Creative Commons
Ecological Role
The Nilgiri langur plays a critical role in seed dispersal. Their diet is made up of such a variety of plant species—over 115 types of shrubs, vines, trees, and more—that they disperse more types of seeds than any other primate in the region.
The Nilgiri langur plays a critical role in seed dispersal. Their diet is made up of such a variety of plant species—over 115 types of shrubs, vines, trees, and more—that they disperse more types of seeds than any other primate in the region.
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Conservation Status and Threats
As of 2008, the Nilgiri langur is classified as Vulnerable by the International Union for Conservation of Nature (IUCN, 2008), appearing on the IUCN Red List of Threatened Species. They face a myriad of threats: poaching, habitat loss, the pet trade, fires, and more. As native trees are supplanted by introduced “fuel wood” trees, these primates continue to face challenges. Some people believe that the Nilgiri langur’s flesh and glands can be used to treat ailments such as asthma, and some drink the blood of this primate. Different parts of the animal are said to serve different purposes—some are even believed to be aphrodisiacs. Aside from being used to make crude medicines, their skins are also used to make drums. Conservation Efforts
The forests where the Nilgiri langur lives are patrolled in order to protect them from poaching. They are also protected under the Indian Wildlife Protection Act, and have been since 1972. There are efforts being made to encourage the Indian government to restore rainforests after they’ve been degraded by industry. |
References:
- https://www.worldlandtrust.org/species/mammals/nilgiri-langur/
- https://www.arkive.org/nilgiri-langur/trachypithecus-johnii/
- http://www.conservationindia.org/news/poaching-for-crude-medicines-continues-to-threaten-nilgiri-langurs
- https://animaldiversity.org/accounts/Trachypithecus_johnii/
- https://en.wikipedia.org/wiki/Nilgiri_langur
Written by James Freitas, November 2018
