The several species of Gibbon are referred to as Lesser Apes. They are smaller than the Great Apes, the Gorilla, Orangutan, Chimpanzee and Bonobo. The largest species of Gibbon is the Siamang which grows to about 14 Kg (31 lb). The Bonobo is the smallest of the Great Apes, on average, and an adult female weighs about 30 kg with a male weighing about 40Kg.
Male and female Gibbons are about the same size. This is different from the Great Apes. In all the Great Apes, the males are bigger than the females. In Humans there is also an average difference in size between males and females.
Depending on which classification you use there are between 8 and 15 different species of Gibbon.
Excluding things that can fly, the Gibbons are probably the most agile of all the animals that live in trees. Typically they inhabit the upper parts of the trees. On the ground they are vulnerable to predators. They can walk on their hind legs, holding their arms above their heads for balance.
In their trees they have few predators, but they can not survive if the trees are removed.
As well as protection, the trees provide the Gibbons with food. Like the Great Apes and Humans they are omnivorous. Their main food is fruit, they also eat leaves. Like me they prefer their fruit ripe, and their leaves young. They will supplement this mainly herbivorous diet with insects, bird eggs and other things they can get easily.
Gibbons live in family groups. Both parents look after their children. The Gibbon is the only ape that is almost exclusively monogamous, and a mated pair appear to stay together till death do them part.
This means that the fathers do know their children. The only other ape where this is usual is the Gorilla, but male Gorillas have several females in their family group.
Gibbons can swing from branch to branch with their arms better than any other animal. They may sometimes swing between branches as much as 12 meters apart. They have excellent binocular color vision like the Great Apes and Humans.
But, of course they can miss. Examinations of captured Gibbons show that broken bones are very common. This also suggests that they frequently survive the injury.
Gibbons appear to use tools less than the Great Apes or Humans, but several instances have been observed.
The few species of gibbon are the most numerous of the apes. They are hunted for meat, pets and traditional medicine. They are fairly vulnerable to poachers because of their loudries.
The main threat to the survival of the Gibbons in the wild is the destruction of their habitat for agriculture and timber production.
Although the Gibbon group of species is still quite numerous, some species are endangered, and in many of the Asian countries they come from they are considered an endangered animal.