Life of the Kalu Wandura
The Kalu Wandura or the Purple-faced langur (Semnopithecus vetulus) is endemic to Sri Lanka and found nowhere else in the world. Given its unique biological status it is an animal that we hold in trust for the rest of the world. However, the International Union for Conservation of Nature (IUCN) has listed the Kalu Wandura as an endangered species and its future survival is in serious jeopardy.
This article describes the Kalu Wandura’s struggle for survival, and hopes to create empathy for an animal whose life style is very similar to ours. It is based on our long-term field investigations of Kalu Wanduras in the cloud forests of Horton Plains, the dry zone forests of Polonnaruwa and the wet zone forests of Waga.
The Kalu Wandura depends entirely on trees for survival. It lives in family groups and eats, sleeps, travels, raises babies, and performs all life functions in the trees. These functions are repeated each day and begin with an early morning chorus, which is a spectacular display of loud calls given by the group’s leader. He gives these calls with breath-taking leaps and jumps among the trees and triggers a chain reaction from all group leaders nearby. This display announces each group’s location and prevents groups from interfering with neighbours as they go about their daily business. In this way the Kalu Wandura minimises conflict with neighbours and leads a life of peaceful coexistence.
The daily routine
Soon after the display the leader moves with his family to a nearby tree for breakfast. Leaves are a staple in the Kalu Wandura’s diet. When in season, flowers, fruits and other plant parts are eaten as well, but leaves are a very important part of the Kalu Wandura’s diet. Leaves are fibrous and also do not contain much energy, but the Kalu Wandura has special adaptations to deal with both issues. To survive on a low energy diet the Kalu Wandura has evolved a very big stomach to consume large quantities of leaves. To deal with fibrous leaves the Kalu Wandura’s stomach contains bacteria that digest fibre into simple sugars to provide energy.
The bacteria however, can do their job only when the animals are at rest. Therefore, the early morning burst of feeding is
A young Kalu Wandura
followed by a period of rest. In this way three or four bouts of feeding alternate with rest periods during the day, after which the adults form huddle groups with youngsters and retire for the night. This pattern of life seems dull and may not appear as interesting as that of a leopard, elephant or a dancing peacock. However, our field investigations have uncovered details of the Kalu Wandura’s life that are truly remarkable. They are remarkable particularly because they have striking similarities to our own lives.
For example, after breakfast the group members gradually make their way to the treetops, to catch the sun’s rays and rid their damp fur of the early morning dew. This is similar to our own habit of using the sun to dry clothes, grains, and other damp items. As the sun gets warmer though the animals move down to rest in the shade of the dense foliage. It is here that many interesting aspects of Kalu Wandura’s social life can be seen. Adult females groom the fur of their infants like human mothers do to keep a child’s hair free of lice and dirt. They also groom each other for the same reason and to reinforce the social bonds between them.
Meanwhile, a young female may walk over and gently pick up a baby from its mother’s lap and hold it to her chest. Learning the essentials of motherhood begins at an early age, and the young female may walk away from the mother with the baby clinging to its chest. The mother keeps a watchful eye, but does not interfere unless the baby squeals in distress. If this happens the mother moves quickly to retrieve her baby and comfort it. Babies either play with similar age mates or fall asleep in the mother’s lap sucking a nipple. Play is an important way for youngsters to develop social and survival skills. It’s no different to young children going to school or having play dates! When watching a group one cannot help but notice the many similarities between the social life of the Kalu Wandura and our own.
Much like us
The similarities are also found in our food habits. Kalu Wanduras are vegetarians, but our field investigations have revealed that the diet of even neighbouring groups can be different. For example, at Waga, the Appu group ate from only 27 plant species, but its neighbour, the Tikira group took food from at least 41 species. The difference in the variety of plants eaten by two groups resembles differences in the diet of people that live as neighbours. Some people are selective in what they eat while their neighbours have a more diverse diet. Both in humans and monkeys family traditions appear to influence food habits; and they seem to be passed on from one generation to the next through social interactions during meals.
Other similarities between people and the Kalu Wandura are also evident. For instance, like most human families, a Kalu Wandura family has exclusive rights to a piece of land called a territory. The territory has well defined boundaries, and can vary in size depending on factors like group size and quality of the forest habitat. And like bedrooms in people’s homes a territory contains special areas for sleeping at night. It also has a “dining room” but the location of this space changes seasonally with changes in food availability within the territory. However, like the land people own, the Kalu Wandura’s territory is defended against trespassers. The loud call is a way of avoiding confrontation, but if this fails skirmishes along territorial boundaries do occur. The leader male is very active in settling these disputes, and does so swiftlyby chasing out the intruders.
Lack of awareness
Few people realise that Kalu Wanduras have a land tenure system similar to ours. When people cut down forests to construct homes and commercial areas, they are actually taking over lands that belong to Kalu Wandura families. Superimposing a human land tenure system over a similar system already established over hundreds of years by Kalu Wanduras is at the heart of the survival problems facing these animals.
When Kalu Wandura territories are taken over by people these animals have nowhere to go to find food and shelter. So they return repeatedly to their former haunts to eke out a living by raiding people’s home gardens. This often leads to people retaliating against Kalu Wanduras, sometimes mildly and at other times quite harshly. Being adapted to life in the trees, these displaced animals try to use live electrical wires like arboreal pathways to move from one place to another and sometimes get electrocuted. As they are ill adapted to terrestrial life they risk getting hit by speeding vehicles or being bitten by village dogs when they move clumsily on the ground.
Death due to electrocution, speeding vehicles, dog bites and direct conflict with humans contribute to Kalu Wandura mortality when they are evicted from natural jungles and forced to live in urban jungles. These types of death add to natural mortality, and the consequences have been disastrous to Kalu Wandura populations all over the country. In fact, all four subspecies of Kalu Wanduras are listed as endangered by the IUCN, but the Western purple-faced langur that lives around Colombo suburbs is listed among the 25 most endangered primates in the world. The Western form is threatened with extinction because of rapid urbanisation around the city.
The widespread lack of awareness of the Kalu Wandura’s needs has been one of the most serious impediments to its survival and peaceful coexistence with people.
This article is written to deal with that lack of awareness, and to ensure that the Kalu Wandura, which we hold in trust for the rest of the world does not disappear forever.
Contact the Friends of Kalu Wandura (phone 2854215, or email indrani.hewagama @yahoo.com)for more information.