White-handed Gibbon

White-handed gibbons primarily eat fruit, but they also enjoy leaves, flowers, stems, shoots, buds, insects, and eggs. When it comes to fruit, these gibbons can be very selective. They will taste the fruit first, only eating it if it is ripe.

The species is found in northern Sumatra, north through Malaysia and Myanmar, and most of Thailand. Unfortunately, they are no longer found in China.

White-handed gibbons live in tropical rainforests and monsoon forests. They spend most of their time high up in the trees, only in the upper canopy. They rarely, if ever, come down to the ground.

Possible predators of white-handed gibbons include raptors, leopards, and pythons.

The primary threat to this species is illegal hunting, both for food and the pet trade. Habitat destruction is another serious issue, especially as roads are built through protected areas. This leads to smaller populations that are more spread out and makes it easier for poachers to access these regions.

These primates are dichromatic, meaning they have two different coat colors: dark shades like gray, black, or brown and lighter shades like cream or light brown. Their faces are hairless and framed by a ring of short white or light-colored fur, and their hands and feet are also white. They do not have tails, and their long arms and hands are specially adapted for brachiation—swinging hand-over-hand among the branches. This movement is similar to how humans move across a jungle gym.

Brachiation is the main way they move through the treetops, which helps them reach the outer parts of the tree canopy where most of their food is found. They also move by walking along branches with their arms outstretched to help them keep their balance.

Special features help them eat, such as their back teeth, which have high points to grind up plant material, and a gut that can handle a diet mostly made up of tough fruits.

White-handed gibbons usually mate for life and live in small family groups that can have two to six members. While the mother is mainly responsible for taking care of the young, the father and older siblings also help with nurturing them.

Gibbons can breed at any time of year and typically have one baby about every three and a half years. The babies are weaned, or stop nursing, at around 18 months old but often stay with their family until they are old enough to mate. Females usually reach sexual maturity between six and nine years old, while males typically mature around nine.

White-handed gibbons use a vocalization called a "term song" to communicate. These songs are a mix of solos and duets that are performed by pairs that are closely bonded. Their calls are very loud, long, and complex. They help signal territory boundaries to neighboring groups of gibbons.

A normal duet consists of three parts: an introductory call, a great call, and an interlude sequence. The introductory call features both gibbons singing a series of notes together. Then, the female starts the great call, and the male responds. Finally, the interlude sequence happens, which can change every time but usually includes notes from both the male and female, along with the male's response.

Usually, their young ones do not join in the singing, but sometimes a female offspring might sing the great call with her mother. These duets typically take place between sunrise and noon, with the most activity around mid-morning. The songs last about 11 minutes and can be heard from over half a mile away!

White-handed gibbons are active during the day, spending most of their day searching for food and eating. They typically spend over 15 hours resting in what are called "sleeping trees," where they stay from a few hours before dusk until the next morning. They dedicate about 10 hours each day to allo-grooming, which is when members of the same species groom each other as a way to bond and socialize.