Leaf monkeys are mostly vegetarians!

Last week we introduced you to a fascinating member of the Animal Kingdom, a species of monkey known as the saki. As we mentioned in that article, there are different kinds of monkeys with varying features, habits and lifestyles.

Today too, we feature yet another relative of ours from the primate world, the Leaf monkey, which is an Old World monkey. Now, if you are wondering why monkeys or for that matter any other animal is called an Old World or a New World animal, let us briefly enlighten you.

Scientists generally classify animals that are native to Africa and Asia as those belonging to the Old World.

There are many differences between the Old and New World creatures and in the case of Old World monkeys or Ceropithecidae too, there are such differences. For instance, several Old World monkeys have anatomical (body structure) oddities, like in the Proboscis with its extraordinary huge nose, and the snub-nosed

monkey which seems to have no nose at all.

Meanwhile, most Old World monkeys are primarily omnivorous, but all prefer plant matter. The majority have tails (unlike apes).

However, they do not have prehensile (grasping) tails like the New World monkeys. Old World monkeys inhabit a range of environments from rainforests to savanna, scrubland to mountainous terrain. Medium to large sized, these monkeys range from arboreal (living in trees) like the colobus, to fully terrestrial (living on land) forms such as the baboons.

The smallest Old World monkey is the Talapoin which is about 0.7 - 1.3 kg in weight and 34-37 cm in length. The largest is the male Mandril which is about 70 cm in length and weighs around 50 kg maximum.

Now, let’s check out what the Leaf monkeys are like ...

Leaf monkeys are considered to be the most vegetarian among monkeys and it is not surprising, taking into account their name.

These diurnal (day time) and arboreal forest dwellers have large stomachs - which are multi-chambered like those of ruminants such as cattle and deer. The forestomach supports bacteria with cellulose (digesting abilities).

Leaf monkeys are classified under different names such as Banded leaf monkeys, Grizzled leaf monkeys, Capped leaf monkeys, Maroon leaf monkeys Silvered leaf

monkeys, Dusky leaf monkeys, Purple-faced leaf monkeys, going by their physical appearance, regions they live in and traits.

The Silvered leaf monkey is about 5-7 feet in length and weighs about 6.6 kg. It is identified by its silver-tipped fur and dark-skinned face. However, the newborns have bright orange coats. Hands and feet and face are white, but turn grey and then black, as they grow.

Like all leaf monkeys, the Silvered leaf monkey too travels about in groups of 9-15 individuals. Travel is initiated and coordinated by an adult male because it has an unimale social structure. The group starts moving before sunrise and stops travelling before it becomes dark. Males usually live a solitary life until they form new groups.

These groups are highly territorial and act aggressively towards other individuals. Fighting consist of slapping and pulling with some biting involved. Females allow other females to carry and care for their young. Adult males have also been observed to carry and care for immature group members.

Social play has been observed among this species of monkey, mostly among juveniles of both gender. But, individuals of all ages also participate. Wrestling is the most common form of play. Juvenile males engage in the most vigorous form of play-fighting.

When communicating, the young males and females make a call which sounds like ho , to address each other from a short distance, while adult females greeting each other says ku - ku. Infants in a peaceful state make a noise that sounds like ku and adult males controlling travel movements of the group say kwah at repeated intervals.

These monkeys make different sounds for alarm calls, attack calls, fear calls and threat calls. They also resort to visual communication such as yawning, branch shaking, head shaking and chasing.

The Silvered leaf monkey gives birth to a single offspring with births occurring throughout the year. The Silvered leaf monkey inhabits Brunei, Burma, Cambodia, Indonesia, Laos, Malaysia, Thailand and Vietnam. Four sub-species have been identified.

The Dusky leaf monkey also called the spectacled langur is found in Thailand and the Malay Peninsula (in southern Asia) in forests, scrublands and plantations. It is a rather common monkey. Being an arboreal forest dweller, it prefers dense forests with tall trees.

This monkey is widely variable in colour; the upper part of the body (or outer coat) may be grey brown or black whereas the under parts, hindlegs and tail are paler. The face is grey and often marked with a patch of white fur located around the mouth and eyes. Hence the name, the spectacled langur.

Its hands and feet which have the ability to grasp, closely resemble those of humans. Palms and soles are usually black and hairless.

The fingers are well developed. Head and body length ranges from 42 to 61 cm and tail from 50 to 85 cm. On average, a healthy adult male would weigh around 7.4 kg and a female approximately 6.5 kg. Newly born Dusky monkeys are bright yellow or orange in colour with a pink face. Within six months the fur changes colour to grey.

Dusky leaf monkeys are diurnal. They are very active by day, but return to their tree roosts in the nights.

The monkeys travel in groups that consist of 5-20 individuals. Social groups usually have one or more adult males, and two or more adult females.

The adult male has three responsibilities - that is to detect predators, hold the group together and patrol the boundaries. The young monkeys always play near an adult female.

This monkey has a wide range of calls that are considered to be quite complex.

It uses a variety of snorts, hoots, murmurs and squeaks to communicate with other members of their social group.

When moving from tree to tree by climbing, leaping and running quadrupedally (on all four limbs) along branches, the motion of the tail plays a significant role in maintaining balance.

The diet consists of young leaves, shoots and seedlings. They feed from 87 different species of trees. In general a Dusky leaf monkey eats up to 2 kg of food per day.

Francois’ leaf monkey, also known as the white side-burned leaf monkey, Francois’ langur or Tonkin is found in southern China (Guangxi and Guizhou Province), central Laos (east of Mekong River) and northern Vietnam.

The family group comprises 3-12 individuals including 4-6 females and several young.

The monkey spends most of its time on trees and sleeps outside during mild weather and in caves during cold winters.

The Grizzled leaf monkey which is also known as the Javan Grizzled Langur, Stripe-crested Langur or the Gray is considered to be endangered, due mostly to loss of habitat. In fact its natural habitat has decreased by about 50 per cent in the last decade alone.

The family groups which number 6 to 7 individuals are very territorial. Endemic to the western half of Java Islands and found mostly in rainforests, the Grizzled leaf monkey is mostly a folivorous (leaf eating) animal with 62 per cent of its diet comprising young or tender leaves and another 6 per cent, mature leaves.

The Banded leaf monkey is suspected to be a subspecies unique to Singapore. It was discovered in 1925. About 68-80 cm in size, it is found in forest habitats restricted to the Central Catchment Area. A small population of this species which is endangered due to habitat loss is found in this area.

Arboreal and gregarious (living in communities) this monkey travels in groups of about 20 individuals. Usually these monkeys move in an extended line. It can leap well from tree to tree.

Meanwhile, Ebony leaf monkeys, also known as lutungs are only found in Indonesia and are becoming rarer. It has a bulge over the eyes and lots of fur on the head. It grows to lengths of 40-80 cm and weighs between 5-15 kg.

Often preferring rainforests, the monkey spends the largest part of the day in trees, crawling along the branches on all fours. But it can jump well from tree to tree like most monkeys.

There are more kinds of leaf monkeys, so try to find out about their interesting lifestyles.

Facts and pix: Internet