Types of Gibbon
Gibbons are classified in the Kingdom Animalia, Phylum Chordata, Subphylum Vertebrata, Class Mammalia, Order Primates, Superfamily Hominoidea (Gray, 1825) and Family Hylobatidae.Gibbons are small, arboreal apes distributed in the wild in the tropical and subtropical rainforests of Southeast Asia. They are currently found in small populations in China, Laos, Vietnam, Cambodia, Thailand, Bangladesh, NE India, Myanmar, Malaysia, and Indonesia. Most countries consider them to be endangered, and they are threatened primarily by loss of their forest habitat. Other factors contributing to their demise include the illegal wildlife trade, the use of their body parts in the manufacture of traditional medicines, and poaching.
Gibbons have long fascinated scientists and lay people because of their agility in the forest tree tops. Gibbons are excellent brachiates (arm-swingers), and this is one reason they make popular zoo exhibits. In the wild, gibbons live in nuclear families consisting of a mated pair and their dependent offspring. The family unit occupies a territory, and they defend its boundaries by a vigorous vocal and visual display. The vocal display consists of a spectacular, bird-like duet between the mated pair, with the young occasionally joining in. This vocalization, or song, is audible for long distances and are the primary way scientists (and poachers) locating wild populations. This haunting melody has become part of the folklore of the indigenous people of Southeast Asia.
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 12 species are categorized in 4 genera: Nomascus, Symphalangus, Hoolock, and Hylobates.
One unique aspect of gibbon physiology is that the wrist is composed of a ball and socket joint, allowing for biaxial movement. This greatly reduces the amount of energy needed in the upper arm and torso, while also reducing stress on the shoulder joint. They also have long hands and feet, with a deep cleft between the first and second digits of their hands. Their fur is usually black, gray, or brownish, often with white markings on hands, feet, and face. Some species have an enlarged throat sac, which inflates and serves as a resonating chamber when the animals call. This structure is enormous in a few species, equalling the size of the animal’s head.
Gibbon skulls resemble those of great apes, with very short rostra, enlarged braincases, and large orbits that face forward. Gibbons have the typical nose of catarrhine primates with nostrils that are close together and face forward and slightly downward. They lack cheek pouches and their stomach is not sacculated. Their teeth also are similar to the great apes, with molars that are bunodont and lack lophs. The upper molars usually have a cingulum, which is sometimes large. The canines are prominent but not sexually dimorphic. The dental formula is:
Gibbon in Thailand
1. White-Handed Gibbon: Hylobates lar
Physical Characteristics: The White-handed gibbon varies from almost black through dark brownto pale buff or cream-colored, but can always be distinguished by its white or buff hands, feet and facial markings. The colour variation is not specific to sex, and animals of either colour can be found together in the same family group. Their approximate weight ranges between5-6kg with a body length of 45-50 cm.
Habits and Behaviors: Gibbons feed on a variety of fruits, young leaves, shoots, flowers andinsects; this species eats more fruit and less leaves than great gibbons(Siamang). They exhibit faster migration over longer longerdistances with a larger territory of 10-50 hectares. The gestation period lasts seven months, or 210 days, and females produce approximately one young every 2-4 years. Althoughinfants are weaned within a two year period, some young may stay with the group for an additional 6-7 years. Group size consists of the mated pair and up to 4 offspring.
Conservation Status: Still quite widely dispersed but listed as Endangered in CITES AppendixU.S. ESA.
2. Pileated Gibbon: Hylobates pileatus
Geographic Range: Limited to south-eastern Thailand, western Cambodia and south- west Laos, west of the Mekong River. Co-exists with White- Handed Gibbon in some parts of central Thailand (Khao Yai National Park)
Physical Characteristics: Pileated gibbons are sexually dimorphic is color. Adult males are all black, except for white border around the face, white genital patch, hands and feet,while adult females are pale grey-brown with black patches on breast and crown. Young animals of both sexes are grayish-white, acquiring black patches like adult females at four to six months. They are relatively the same size as the White-Handed, weighing between 5-6 kg and having a total body length of 45-50 cm.
Habits and Behaviors: Pleated gibbons eat leaves, fruits, flowers, buds, and insects. The majority of their diet consists of fruits, including figs. They also eat other invertebrates, bird eggs, and small birds. They share similar habitat to the White-Handed gibbon, although they can also occur is more open, partly deciduous forest; also share similar gestation period and group dynamics.
Conservation Status: Seriously Endangered – Listed as Endangered in CITES Appendix I, U.S. ESA and IUCN.
3. Agile Gibbon: Hylobates agilis
Geographic Range: Agile Gibbon has three distinct populations, each with limited overlapwith other gibbon species.
- Population occurs in peninsular Malaysia and Thailand, with White-Handed gibbons to both north and south.
- The population in southern Sumatra is replaced to the north by the White-handed gibbon.
- In Borneo, H.aalbibarbis is found in west and central Kalimantan between the Kapuas and Barito Rivers, being replaced in rest of island by Borneo’s Gibbon.
Physical Characteristics: Agile gibbons are quite variable in color, ranging from cream to dark brown, generally with white eye-brows and sometimes with pale cheek patches that may join under the chin. Hands and feet are same color as rest of fur, unlike White- Handed gibbon. Bornean race is less variable that others, being usually buff below and dark brown above. Their size is similar to White- Handed gibbon, weighing between 5-6 kg and having a total body length of 45-50cm.
Habits and Behaviors: The Agile gibbon feeds on a variety of fruits, young leaves, shoots, flowers, and insects. They share a similar territory type and size with that of the White-Handed Gibbon; also share similar gestation period and group dynamics.
Conservation Status: Still fairly abundant, but listed as Endangered in CITES Appendix I and U.S. ESA.
4. Saimang: Hylobetes syndactylus
Geographic Range: Their range is now restricted to peninsular Malaysia, along Thailand’s southern border and Sumatra.
Physical Characteristics: The Siamang Gibbons are completely black with somewhat shaggy fur, and abare throat pouch that inflates when the animal is calling. They are the largest gibbon having a stocky build; weighing an average 11-12 kg with a total body length of 75-90
Habits and Behaviors: Diet consists mainly of leaves, fruits (especially figs), flowers, and shoots. It eats relatively more leaves than smaller gibbons. They are found mainly in evergreen tropical rain and hill forests and defend a territory smaller than that of the White-Handed gibbon, given that they are less mobile. The gestation period is slightly longer, being 230-235 day and give birth to one young approximately every two or three years. Family group consists of two breeding adults and up to three dependent young.
Conservation Status: Listed as Endangered in CITES Appendix I and U.S. ESA.
Where the Gibbon live?
Native to the dwindling rain forests of South and Southeast Asia, gibbons are arboreal and considered to be among the world’s greatest acrobats. They have the ability to swing from tree to tree 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 handsis called brachiating. Gibbons are one of the few monogamous primates, and whether on the ground or in the trees, they are known for their dexterity and ability to walk upright. Often referred to as the “songbirds” of the primate family and the most musical land mammal, gibbons can project their voices up to 2 miles through the dense rainforest canopy. Unfortunately, their natural habitat is being destroyed at the alarming rate of 32 acres per minute!
Gibbons live in the tropical and less seasonal rain forests of South and Southeast Asia, from the northeastern tip of India to southern China, across Bangladesh and the Malaysian peninsula to Borneo, Java, and Sumatra, including the Mentawai Islands. All gibbon species live allopathically, with the exception of the Siamang (S.syndactylus), which occurs sympatrically with white-handed gibbons (H.lar) in northern Sumatra and agile gibbons (H.agilis) on southern Sumatra and the Malaysian mainland. A few small natural hybrid zones exist in Thailand, Malaysia, and in Kalimantan, Indonesia.