(Hoolock leuconedys)

IUCN status : Vulnerable

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Hoolock Gibbons are the only apes of India. Apes can be distinguished from the monkeys with much longer and stronger arms than their legs. Apes do not have tails, while most monkey species do. Apes tend to be larger than monkeys and usually have larger brains. Ape species are much closer to humans than monkeys are. In addition to having similar basic body structures, apes are highly intelligent and can exhibit human-like behavior. For example, chimpanzees, which are closest to humans genetically, can create simple tools and use them effectively. There are two subspecies of Hoolock Gibbons – The Eastern Hoolock Gibbon found in the north-eastern corner of Arunachal Pradesh and the Western Hoolock Gibbon found in all the seven north-eastern states of India.

Gibbons are known most for their shrill calls. With the first rays of the sun, the family consisting of a group of 6-7 members starts jumping from tree to tree. It is then that one member, usually the father starts calling – a loud howl reverberating in the depths of the jungle. This is followed by calls of the other members of the family, chitchatting and progressing through the tree tops. It is believed that the name Hoolock too is derived from the Assamese or Hindi word ‘ulluck’ meaning the loud call or howl of the gibbon. In Nagaland and Assam there was once a time when people calculated the time of the day according to the howls and hooting of the Gibbons. With the morning calls, the farmers knew it was time to go to their fields. In the afternoon when the female gibbon would make a great call which was followed by the male, people knew it was time for lunch.

It is said that gibbons rarely put their feet on the ground, spending most of their day on the top most branches of the trees, swinging effortlessly through the forest using its long arms. The mode of locomotion is known as brachiation.