An excited whoop erupts from deep in the forest, boosted immediately by a dozen other voices, rising in volume and tempo and pitch to a frenzied shrieking crescendo. It is the famous ‘pant-hoot’ call: a bonding ritual that allows the participants to identify each other through their individual vocal stylisations.
To the human listener, walking through the ancient forests, this spine-chilling outburst is also an indicator of imminent visual contact with man’s closest genetic relative: the chimpanzee.
Noisy and curious, intelligent and sociable, chimpanzees fascinate humans and are favourites both in zoos and the wild.
The chimpanzee has a thickset body with long arms, short legs and no tail. Much of the body is covered with long black hair, but the face, ears, fingers and toes are bare. They have hands that can grip firmly, allowing them to pick up objects. The discovery that they used "tools" for certain purposes surprised the world.
Chimps are mainly found in rain forests and wet savannas. While they spend equal time on the ground and in trees, they do most of their feeding and sleeping in trees.
Chimps live in groups, called troops, of some 30 to 80 individuals. These large groups are made up of smaller, very flexible groups of just a few animals, perhaps all females, all males or a mixed group. Chimps sometimes chew leaves to make them absorbent and then use them as a sponge, dipping them in water and sucking out the moisture. They also use grass stems or twigs as tools, poking them into termite or ant nests and eating the insects that cling to them. They are able to wedge nuts between the roots of a tree and break the shells open with a stone.
Chimps are both arboreal and terrestrial, spending much of their daytime hours on the ground. They are quadrupeds, walking quickly on all fours with the fingers half-flexed to support the weight of the forequarters on the knuckles. They occasionally walk erect for short distances. Chimps are agile climbers, building nests high up in trees to rest in during midday and sleep in at night. They construct new nests in minutes by bending branches, intertwining them to form a platform and lining the edges with twigs. In some areas chimps make nests on the ground.
Chimps are diurnal (but often active on moonlit nights) and begin their activities at dawn. After descending from their night nests they hungrily feed on fruits, their principal diet, and on leaves, buds and blossoms. After a while their feeding becomes more selective, and they will choose only the ripest fruit. They usually pick fruit with their hands, but they eat berries and seeds directly off the stem with their lips. Their diet consists of up to 80 different plant foods.
The female chimp has an estrus cycle of about 34 to 35 days. While in heat, the bare skin on her bottom becomes pink and swollen, and she may mate with several males. She normally gives birth to just one baby, which clings tightly to her breast and, like a human baby, develops rather slowly. An infant can sit up at 5 months and stand with support at 6 months. It is still suckled and sleeps with its mother until about 3 years of age, finally becoming independent and separating from her at about 4 years.
Sexual maturity is reached between 8 and 10 years. Chimps are among the noisiest of all wild animals and use a complicated system of sounds to communicate with each other. Chimps touch each other a great deal and may kiss when they meet. They also hold hands and groom each other. An adult chimp often has a special "friend" or companion with which it spends a lot of time. Female chimps give their young a great deal of attention and help each other with babysitting chores. Older chimps in the group are usually quite patient with energetic youngsters.