Leap Like A Langur

Leap Like A Langur

The verdant mountains of the Western Ghats are a home to several endemic plant and animal species, meaning they are found only in these forests and nowhere else in the world. Conspicuous among the mammals are the primates, that inhabit the lush forests and bring them alive. Of the five primate species that occur in these mountains, the Nilgiri langur (Semnopithecus johnii) and the Lion-tailed macaque (Macaca silenus) are entirely forest dwelling species. The Nilgiri langur is a leaf monkey and is found in the moist forests of southern Western Ghats. The loud resounding 'whooping call' of the Nilgiri langur amidst myriad forest sounds leaves an indelible impression of wilderness as you pick your way and trek through these mist covered rainforests.

These gentle monkeys typically live in small troops of 8 to 10 individuals. Troops usually consist of one male, with four or five females and their young. However, troops with two or more males can be occasionally seen. Like many primate species, males emigrate on reaching adulthood. Ousted males wander around alone or form 'bachelor bands' with other solitary males and wait for an opportunity to take over a troop. The solitary males and the bachelor bands would however have to watch out for the vigilant adult territorial males occupying treetops and scanning the surrounding for intrusions. Females, however, prefer to stay behind.

These monkeys are sedentary owing to the fact that their food resources are more or less ubiquitous, making it unnecessary for them to travel great distances in search of food like the macaques. Their folivorous diet requires long hours of digestion and hence prolonged hours of resting.


As in most primates, males are generally more dominant than the females. Females also exhibit a dominance hierarchy but rarely any overt aggression commonly seen among other primates. Interactions among the members of the troop normally involve moving away and looking away from the dominant individual with or without certain vocalizations such as 'squealing' or 'screeching'. In females, a form of 'affiliative' behaviour is sometimes seen. When two females meet each other or if a subordinate individual happens to come close to a dominant one, the subordinate one squeals and they embrace each other. However, even among the males, overt aggression is rare in this species.

If such peaceful coexistence and 'affiliative' behaviour is appealing, then the display of 'allomothering' behaviour where the infants are sometimes taken care of by females other than the mother in the troop is fascinating. This is a common feature of most colobines and also observed among Nilgiri langurs. Often other females would sit around the mothers and groom them and their infants. This attraction of other troop members continues till the infant is around ten weeks old.

A striking feature of Nilgiri langur is the neonatal pelage colour, another trait of leaf monkeys. Newborn infants have a dull yellow pelage which gradually changes to black in the course of 8 to 9 weeks. In some south-east Asian species, the infant coat colour is bright orange and the adult coat is grey. It is intriguing then, that why should infants appear so strikingly different from adults making them vulnerable to predators or for that matter to males having infanticidal tendencies? Various hypotheses have been offered to explain significance of natal coats in primates. The most common one being that the stark pelage colour of infants serves as a trigger for 'alloparental' behaviour among females.

Nilgiri langur has been historically hunted, and in some sites it continues to be hunted. Its flesh, blood and some organs are believed to contain certain medicinal properties. Certain communities consider 'kari manthi rasayanam' (Black monkey tonic) a cure for lung ailments and general debility.

Habitat loss and destruction are other factors that cause a population decline. Sadly, for this primate, its territorial call is a give-away of its presence. In forests where there is severe hunting pressure, there is deafening silence and one rarely hears the characteristic 'whooping' call. There are also a few other problems apart from habitat loss and hunting which are far more insidious. Infrastructure development such as construction of roads, rail and power lines, poses a greater ecological threat. They not only cause a break in the forest canopy but more seriously open up access to forest areas that were hitherto inaccessible and untouched, often resulting in encroachment of forest land. This is not just a conservation problem for the Nilgiri langur but poses a threat to all wildlife. In places where power lines criss-cross its habitat creating canopy discontinuity, there have been cases where these primates have died due to electrocution while trying to leap from tree to tree.

Intensive protection against hunting, responsible infrastructure development that integrates conservation, and creating awareness among the local communities are a few measures that could be taken up to ensure our forests continue to reverberate with the 'whooping calls' of the Nilgiri langur.


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