Top 11 Fascinating Facts About the Gibbon

Gibbons are native to the dense forests of Southeast Asia, perfectly adapted to an arboreal lifestyle, rarely descending to the ground. Their strong, hook-like hands make it easy for them to grasp branches, while their long, powerful arms allow them to stretch great distances. Their legs are also long, flexible, and strong, providing propulsion and aiding in branch gripping. The structure of their shoulder joints allows for exceptional movement range when swinging through the trees.

Gibbons move through the forest using a specialized form of locomotion called 'brachiation,' reaching speeds up to 56 km/h and covering distances of up to 15 meters with a single swing. This unique form of movement also enables them to access fruit at the highest points of branches, reducing competition for their preferred food.

When walking, whether on branches or, less commonly, on the ground, gibbons use their two legs and raise their arms above their heads for balance. Gibbons are the most frequently studied primates in relation to the theory of human bipedalism.

Gibbons are monogamous, a rare trait among primates. They live in family groups consisting of a mated pair and their offspring. These families define and defend their territory through loud calls that can carry for miles across the forest. The pair, or even the whole family, sings long and intricate songs, and some species have large throat sacs to amplify their vocalizations.

Gibbons use a wide range of vocalizations, akin to human language, to communicate. They have specific calls to warn of different predators, such as leopards and snakes. For example, they make a unique sound to signal danger from big cats like tigers and leopards, and a distinct call for birds of prey like eagles and hawks. Some subtle variations in these calls suggest that gibbons may even convey which specific predator they have spotted.

Their calls are highly specific, even including signals to let others know whether a predator is stationary or moving. Female gibbons have a richer “vocabulary” compared to males. While the male might simply call out, “We are under attack,” it is the females who lead, giving instructions on what to do. For instance, they might say, “Leopard! Climb higher.”

Even more intriguing, gibbons can adjust the frequency of their calls to avoid detection by predators. By using lower frequencies, they can alert others without giving away their position to the predator, staying one step ahead.

These iconic tree-dwelling creatures are among the most endangered primates on Earth. Their habitats are rapidly disappearing, and gibbons are often captured and sold as pets or killed for use in traditional medicine. Many species of gibbons are classified as Endangered (EN) or Critically Endangered (CR).

In captivity, gibbons require very specific environmental conditions to ensure their physical and behavioral needs are met. Without an appropriate habitat that allows them to display natural behaviors, they suffer from poor welfare.

Examples of well-managed captive environments for gibbons include zoos in Melbourne, Pittsburgh, London, and Twycross. In these facilities, gibbons live in spacious enclosures modeled after their natural habitat, with plenty of opportunities for climbing, swinging, and enrichment activities that allow them to engage in their natural behaviors.

Gibbons, often referred to as small ape-like monkeys, are distinct from other primates in that they lack tails. They have exceptionally long arms and slender fingers. These primates are predominantly arboreal, spending most of their time in the trees and rarely descending to the ground.

There are about 11 different species of gibbons worldwide, and 5 of these species are native to Vietnam. Gibbons have a slow growth rate, making them highly vulnerable to extinction due to hunting in Vietnam. Unlike species like gorillas or chimpanzees, gibbons are smaller in size and exhibit unique characteristics, such as using their arms to swing from tree to tree.

Gibbons feed primarily on ripe fruits, foraging in the trees. They live in family groups consisting of both males and females. These groups establish and defend territories, often marking their boundaries through vocal calls, alerting other gibbons of their presence.

The lemur, native to Madagascar, is home to over 100 different species. While many of these gibbons eat a variety of fruits and leaves, some species have specialized diets, feeding primarily on one type of food. Gibbons are found in both broadleaf forests and mangrove habitats, though they face increasing threats. These threats include habitat destruction from deforestation, hunting for bushmeat, capturing them for the exotic pet trade, and the impacts of climate change.

Another species is the white-cheeked gibbon (Nomascus leucogenys), also known as the black-cheeked gibbon or singing gibbon. Males have black fur with distinct white cheeks, while females have darker golden fur. Their faces often have a gray patch on the top of their heads, and some gibbons have a white ring around their faces for identification. These gibbons typically weigh between 7 and 12 kilograms and measure from 74cm to 90cm in height.

They follow similar reproductive behaviors to other gibbons, foraging during the day and sleeping in trees at night. Gibbons are typically found in forests in regions such as Lai Châu, Hòa Bình, and Thanh Hóa in Vietnam.

Another type of gibbon, the golden-cheeked gibbon, is distinguished by its golden or dark orange cheek fur. These gibbons are smaller than the white-cheeked variety, standing at 50-60cm tall and weighing no more than 10kg. They are primarily found in Cambodia, though some exist in the Quảng Trị, Nghệ An, and Quảng Bình regions of Vietnam.

Lastly, the tailless black gibbon (Nomascus concolor) is another fascinating species. Males have solid black fur with a few white whiskers around their mouth, and a tuft of hair on top of their heads. Females have golden fur with dark brown patches on their chest. These gibbons are active during the morning and evening, foraging in trees and calling loudly at dawn.

Each gibbon has its own territory, marked by loud calls that can be heard within a 1km radius. These calls serve multiple purposes: to attract mates and to announce territorial boundaries. If a female gibbon is attracted by the call, she will approach for mating.

Gibbons typically mate for 3 days, with each species having its own unique mating habits. They are commonly found living in pairs or small family groups of 2 to 4 individuals. Gibbons begin to reproduce around 8-9 years of age and, similar to humans, they give birth to one offspring each year. Their gestation period is shorter than humans, lasting only 5-7 months.

Newborns are covered in soft, light-colored fur resembling their mothers. By the time they reach 1-2 years old, their fur darkens to a deep black. Gibbons are omnivorous, feeding on a variety of foods including bird eggs, fruits, young tree shoots, insects, and even young birds.

According to reports, among the six gibbon species in Vietnam, three are at the highest risk of extinction: the Cao Vit gibbon (Nomascus nasutus), the Black Gibbon (Nomascus concolor) from the Northwest, and the White-cheeked Gibbon (Nomascus leucogenys). The populations of the other three species – the Southern White-cheeked Gibbon (Nomascus siki), the Northern Yellow-cheeked Gibbon (Nomascus annamensis), and the Southern Yellow-cheeked Gibbon (Nomascus gabriellae) – are also declining.

The main threats to the gibbon populations in Vietnam, according to the FFI, are poaching and habitat loss. Even within protected areas, illegal logging, the expansion of agricultural practices, and infrastructure development such as hydropower dams continue to pose significant threats. Additionally, the construction of new roads makes it easier for poachers to access these areas.

Although most gibbon species live in protected areas, their numbers are still rapidly declining, and they may vanish in the near future. The following gibbon species in Vietnam are critically endangered:

• The White-cheeked Gibbon (Nomascus leucogenys) is found in northern Vietnam and Laos and is classified as 'Endangered' by the International Union for Conservation of Nature (IUCN).
• The Southern Yellow-cheeked Gibbon (Nomascus gabriellae) is found in Vietnam and Cambodia and is classified as 'Critically Endangered' by the IUCN.
• ...

Vietnam: The gibbon has appeared in Vietnamese folklore, such as in the folk song "Lý qua đèo" from Hue or "Ăn ở trong rừng" from Quan họ Bắc Ninh. The Vietnamese opera style ca trù also mentions gibbons in its xẩm huê tình melody. In southern Vietnam, there is a proverb referring to the gibbon, symbolizing the wild and distant:

"Mother, don't marry me off too far,
When the birds sing, and gibbons call, where would you know my home?"

Another Vietnamese saying goes: "When the gibbon leaves the tree, it will eventually fall." In literature, two great works, *Truyện Kiều* and *Lục Vân Tiên*, both mention gibbons, especially their calls (also referred to as songs). In the Four Pillars of Worship belief, the gibbon represents the wild mountain regions when it offers fruits as offerings.

China: Gibbons were present in the southern regions of China at least until the Song Dynasty. By the 14th century, they began to disappear due to human-induced environmental destruction. Ancient Chinese literature regarded gibbons as "noble", like the "gentleman" of the forest, while the golden monkeys were seen as seduced by human food. Taoism imbued the gibbon with mystical qualities, believing that they could live for a thousand years and transform into humans. Chinese art has depicted gibbons since the 3rd-4th century BCE (Zhou Dynasty), and they were also a popular subject among artists during the Song and early Yuan dynasties, such as the works of Dì Yùan Gè and Mù Xī Fǎ Cháng.

Japan: Influenced by Chinese culture, the Zen motif of "the gibbon catching the moon's reflection in water" became widespread in Japanese painting, even though no gibbons exist in the wild in Japan.

The Gibbon family (scientific name: Hylobatidae) consists of several species of gibbons. The extant species are divided into four genera, based on their diploid chromosome count: Hylobates, Hoolock, Nomascus, and Symphalangus. The extinct species Bunopithecus sericus was considered a gibbon-like primate and was once thought to be closely related to the white-cheeked gibbon. Gibbons can be found in tropical and subtropical rainforests, from northeastern India to Indonesia, including islands like Sumatra, Borneo, and Java, and extending northward to southern China.

Also referred to as small gibbons or lesser apes, these species differ from larger apes like chimpanzees, gorillas, orangutans, and humans in that they are smaller in size, exhibit minimal sexual dimorphism, do not build nests, and share certain features with monkeys. Unlike larger apes, small gibbons form lifelong pairs. They are particularly remarkable for their ability to move by brachiation, swinging from branch to branch, sometimes spanning distances of up to 15 meters at speeds of 56 km/h. They can leap up to 8 meters and occasionally walk on two legs, raising their arms for balance. Gibbons are the most agile and graceful of all tree-dwelling mammals that do not fly.

The color of a gibbon's fur can range from dark to light brown, and may feature black or white patches, depending on the species and sex. Completely white gibbons are extremely rare. Notable species include the black gibbon, white-handed gibbon, and white-cheeked gibbon. The largest gibbon species, the siamang, is distinguished by the fusion of two toes on each foot.

One of the distinctive features of gibbon anatomy is the ball-and-socket joint in their wrists, which allows movement along two axes. This adaptation eliminates the need for excessive upper body strength in the shoulders and torso. Consequently, the shoulder joint experiences less strain during brachiation. The proportion of the arms to the body in gibbons is greater than that of most other mammals, giving them an impressive arm span. The distance between the thumb and index finger is also notably wide, providing a firm grip for swinging through the trees.

The fur of gibbons typically ranges from black, gray, to brown, and often includes white patches or streaks on the hands, feet, and face. Male gibbons sometimes exhibit darker streaks mixed with their white fur. Some species also feature large throat sacs, which act as resonators during their calls. The size of the sac can be nearly as large as the animal's head.

The skull and teeth of gibbons resemble those of larger apes, while their noses are similar to those of all primates with narrow nasal passages.

Gibbons live in social groups and are territorial animals. Each group occupies a specific area, which they defend by calling out or displaying their presence. Their calls can travel up to 1 km, typically made by a pair of mating gibbons. Occasionally, juvenile gibbons join in the vocalizations.

When a lone gibbon calls, it is usually a male (rarely a female) seeking a mate, announcing its territory, or looking for a companion. If a female is attracted by the call, she will approach, mate, and form a bond. Mating sessions can last up to three days, with several bouts of copulation. During this period, the sound of gibbons calling and singing can make them vulnerable to poachers, who hunt them for meat and other body parts for the wildlife trade, including traditional medicine. Each gibbon species has its distinct call, which allows scientists to identify them and determine their habitat.

The ball-and-socket joints in gibbon hands enable them to move swiftly and precisely through the treetops. However, should they lose their grip or if a branch breaks, they are prone to injury. It is estimated that each gibbon breaks at least one bone during its lifetime.