(Dr. Girish Chandra)
There are 12 living gibbon species, whose coloration range from cream to brown, gray and black. In some species the males and females have a sex-specific coloration. The color of infants of some species is different from the adults.
The species are categorized in 4 subgenera: Nomascus, Symphalangus, Hoolock, and Hylobates.
Native to the dwindling rain forests of Southeast, South, and East Asia, gibbons are arboreal and considered to be among the world's greatest acrobats. They have the ability to swing from tree to tree of distances of 50 feet, at speeds of up to 35 mph, while in trees 200 feet above the ground. This mode of locomotion, swinging under branches while suspended by their hands, is called brachiating. They are the most musical land mammal, their voices can be heard up to 2 miles through the dense rainforest canopy.
Siamangs are slightly larger than other gibbons, 74 to 89 cm tall and about 10 kg in weight. Males, females, and infants have a long, shaggy black coat all over their body, except for some pale hairs around the mouth and chin. Males have a longish tuft of hair in the genital region. Siamangs have a grayish or pinkish throat sac, which they inflate during shouting. Their arms are even longer compared to the legs than white-cheeked, and their hands and feet are broader. The arm length may reach 2.5 times the length of the body. There is slight webbing between their second and third toes.
The different subspecies of gorillas live in different parts of western Africa. Gorilla gorilla, the western lowland gorilla, is found at low altitudes in Cameroon, Central African Republic, Gabon, Congo, and Equatorial Guinea. G. graueri, the eastern lowland gorilla, is found in eastern Zaire. G. beringei, the mountain gorilla, is found at high altitudes 5,400 to 12,440 feet. in Zaire, Rwanda, and Uganda.
Gorillas are shy, social animals that are active during the day (they are diurnal). They live in small groups of 6-7 individuals, including one silverback (adult male), a few females, and their young.
Gorillas are large, quiet, gentle apes that live in Africa. They have a very large head with a bulging crest on top. Male gorillas are much larger than the females, and are almost twice as heavy. Adult male gorillas may weigh as much as 180 kg. and are called silverbacks because they have a saddle-shaped patch of silver hair on their backs after they are about 12 years of age. Gorillas are predominantly herbivores, eating mostly plant material. They forage for food in the forests during the day. They eat leaves, fruit, seeds, tree bark, plant bulbs, tender plant shoots, and flowers. Each evening, gorillas construct a "nest" made of leaves and branches for the night in which they will curl up and sleep.
Bornean orangutans (Pongo pygmaeus) currently inhabit only the island of Borneo, excluding the southeastern portion of Borneo. Pongo pygmaeus was until recently considered the only orangutan species. Sumatran orangutans (Pongo abelii) are now considered a separate species.
Orangutans are sexually dimorphic. Females range from 30 to 50 kg, whereas males are from 50 to 90 kg. Head and body length is about 1.5 meters and the arms have a spread of about 2.2 meters. They have a thin, shaggy coat that is reddish brown in color. Males have large goiter made up of deposits of subcutaneous fat bound by connective tissue.
Orangutans do not form large social groups. Individuals usually travel alone or in small groups consisting of 2 females, their dependent young, and occasionally an adult male. Generally males and females come together only to mate, and otherwise do not associate with one another. Males' home ranges are often 2 to 6 sq. km. and overlap the ranges of several females but not with other males.
The diet consists mainly of fruits, especially figs. They will also eat other kinds of vegetation such as leaves, bark, buds, and flowers. They also eat mineral-rich soil, insects, and possibly eggs and small vertebrates.
CHIMPANZEE (Pan troglodytes), found in Zaire, Uganda and Tanzania, Sierra Leone, Congo.
BONOBO or Dwarf Chimpanzee (Pan paniscus), found only in South Congo.
They are black or dark brown in colour, 5 feet tall, with arms and legs of same length. Bonobo is one-third of the common chimpanzee and is darker in colour. Sexual maturity is reached in 7-8 years. They are brachiators, swinging on tree branches and very playful and extremely noisy. They defend themselves by screaming, jumping, thumping ground and throwing stones and sticks. Chimps are omnivorous and sometimes hunt small monkeys and share their flesh. Their cranial capacity is 365 cc.