An Asian Species of Leaf Eating Monkey
The Asian langurs belong to the family Cercopithecidae and subfamily Colobinae, or leaf-eating monkeys. (The other major group in the subfamily colobinae are the African colobus monkeys, which share similar diets but are found only in Africa.) The best known Asian leaf-eating monkey species is probably the Hanuman Langur, considered sacred by the Hindus of India.
The Hanuman Langur (Semnopitheaus entellus) is adapted to eating tough food which others find indigestible. They can even eat seeds with high levels of the toxins like strychnine (Strychnos nox-vomica) and distasteful vegetation avoided by other creatures. They feed mainly on leaves and other vegetation but also search the ground for fallen fruit and nuts. They also snack on insects, fungi and tree gum. They may even eat soil or stones, probably for minerals to help detoxify their food. They are thus found in a wide range of habitats from the plains to forests.
With long strong limbs, the Hanuman Langur runs fast on the ground on all fours, and climbs well and is agile among trees, its long thin tail providing balance. Their horizontal leaps average 3-5m but can reach up to 13m with some loss of height. But it is more nervous on the ground, and will flee to the trees when in danger. They usually only move on the ground when trees are scarce. They forage during the morning and late afternoon. The troop returns to the same sleeping tree every night. They sleep at the ends of branches, where it's hard for a large predator to get at them. Sometimes, they sleep in caves.
Social life: Two different social structures have been observed. One with a dominant male and several females, usually found in places where food supply is seasonal. Another with many males, usually found where food is abundant. In the groups with several males, the high-ranking males can mate with any females, the other males can only mate when they can sneak by the high-ranking males. These groups can range average 13-37 with 2 females to every male. But this can swell to 125 when several groups gather at food rich areas. Males without females form bachelor groups of 2-32. Females generally remain in their natal group but sometimes, younger males may form their own group by breaking off with some females. Older males may live by themselves. All members of a group join in a booming whoop in the morning, helping to space the groups apart in the dense canopy. They also whoop when they're happy.
Males compete aggressively to be the only dominant male in the group. Thus males in such groups rarely hold on to their position for more than 2 years. Sometimes, bachelor groups can attack the male in the single-male group, together driving him out. The highest-ranking male in the bachelor group then becomes the dominant and chases out the others. With a change in leadership, all male young which are weaned are chased out and infants of both genders may be killed. In this way, the females come quickly into heat (within 2 weeks) and the male can produce more offspring within his 2-year tenure. Normally, females bear young once every 1-2 years. Within hours of birth, the newborn is looked after by other females. It is not uncommon for young to be abused until they are about 5 weeks old. They are kicked or hit, often hard enough to draw blood.
Status and threats: Hanuman is the Hindu god of healing and worship and in many parts of India, the Hanuman langur is considered sacred. The Hanuman langur often travels in the company of Indian holy men. Many Hindus leave them unmolested and even permit them to freely plunder their grain shops. However, this has made the langurs fearless. During food shortages, humans often retaliate. They are also threatened by habitat loss. There are an estimated 230,000 Hanuman langurs left in India.
Size: Head and body 41-78cm, tail 69-1m, 5-23kg. Male is larger than the female.
Lifespan: 20 years in the wild, 25 years in captivity.
Babies: One young, twins rare. Gestation 190-210 days, breeding season varies with location. Weaned in 10-12 months. Female matures in 3-4 years, male 4-5 years but does not mate until 6-7 years. Distribution: Only in the Indian subcontinent: Bangladesh, northwest India, southern Himalayas, Sri Lanka.
Habitat: Found in a wide range of habitats from desert edge to rainforest and mountain scrub at 4,000m. Because they are considered sacred there, they are found even near urban areas in northern India.