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Hylobates larwhite-handed gibbon

By Andrea Smith

Geographic Range

Hylobates lar is found in the tropical rainforests of southern and S.E. Asia, including Thailand, Malaysia, Indonesia, and the area encompassing Southern China to Eastern Burma.

Habitat

This species is found in the tropical rainforest, where it occupies only the upper canopy. These gibbons rarely, if ever, descend to the forest floor. This fact alone makes them very hard to study.

Physical Description

Hylobates lar weighs 5.5 kg on average. Individuals are either dark brown to black in color, or red buff color with white face-rings, hands, and feet. Colors are not specific to sex. Males and females can show either color, but their white "accents" are always present.

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    4.5 to 6 kg
    9.91 to 13.22 lb

Reproduction

Lar gibbons are monogamous.

Gibbons have no fixed season for breeding. The gestation period lasts around seven months, and females produce approximately one young every two years. Young are weaned by the time they are about two years old. In most gibbons, reproductive maturity is reached around 8 years of age. Although they are probably completely capable of caring for themselves at an earlier age, young gibbons do not leave their family group until they reach sexual maturity.

  • Breeding interval
    Females produce approximately one young every two years.
  • Breeding season
    These gibbons breed year round.
  • Range number of offspring
    1 to 2
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    7 months
  • Average gestation period
    217 days
    AnAge
  • Average birth mass
    307.2 g
    10.83 oz
    AnAge
  • Average weaning age
    24 months
  • Average age at sexual or reproductive maturity (female)
    8 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    2555 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    8 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1825 days
    AnAge

Although infants are weaned within a two year period, young stay with the family group for a few additional years. Although the bulk of parental care, including nursing and grooming, is the responsibility of the mother, the father and older siblings also help out.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • male
      • female
  • post-independence association with parents
  • extended period of juvenile learning

Lifespan / Longevity

Data are not available for this species, but other members of the genus Hylobates are known to reach ages of 44 years in captivity. Wild individuals are thought to live around 25 years. It is likely that H. lar is like other members of the genus in terms of its lifespan.

Behavior

These gibbons form small groups consisting of one mated pair and their offspring. Mated pairs tend to stay together in the same territory for their entire life-span, and they continue to have new young as mature offspring leave the group. There is some evidence of "divorces," where the male or female leaves his or her mate for no obvious reason and mates with another individual.

All gibbons are known to defend their territories from conspecifics using calls. These calls are usually very loud, and typically are duets, with both males and females calling.

Communication and Perception

As in all species of gibbon, these animals use vocalizations to defend their territorial boundaries. In addition to these vocal communications, primates are known to use a variety of visual signals, such as facial expressions and body postures, to communicate. Tactile communication, such as grooming and playing, is important within the family unit.

  • Other Communication Modes
  • duets

Food Habits

Lar gibbons are one of the pickiest eaters in the primate world. They are mainly frugivores, but they will also eat other plant matter. They consume ripe fruit only, and only new leaves and buds. They have several adaptations for feeding. One of them is brachiating locomotion, which involves swinging from branch to branch by their arms. This style of motion allows them to reach the periphery of the tree canopy, where most of their food is found. Other adaptations include high cusps on their back teeth to help grind plant matter, and a gut adapted for a folivorous diet.

  • Plant Foods
  • leaves
  • fruit
  • flowers

Predation

Incidents of predation on these animals have not been recorded. It is likely that because they inhabit the upper canopy, they do not often fall victim to terrestrial predators like leopards. Any predators they do have must be able to reach them in the canopy, where the thin tree brances do not permit heavier animals to travel. Because of this, it seems that to the extent that predation occurs, these animal fall victim to raptors.

Ecosystem Roles

As frugivores, these animals are probably important in seed dispersal.

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans

Economic Importance for Humans: Positive

Lar gibbons do not play a very important role economically. They provide some food for humans, but not on a large scale. Although many primates are used for biomedical reasearch, gibbons are not often used for this purpose. They are occasionally captured for the pet trade.

Economic Importance for Humans: Negative

Hylobates lar is not known to have any negative impact on humans.

Conservation Status

This species is threatened for a several reasons. These gibbons are hunted for meat in some areas. Live capture for the pet trade also poses a serious problem. In many Asian countries, it is "fashionable" to own your own primate, and this has led to the death of many gibbons either at the time of capture or during transport. The final, and greatest, threat to these gibbons is deforestation. Rainforests are disappearing at an alarming rate due to logging and agricultural, leaving forest species with an ever smaller region in which to live. Some efforts are being made to save these primates, such as national parks and reserves, but they are not very effective. Laws protect them from live capture, but they are rarely enforced. Listed in CITES Appendix 1.

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Andrea Smith (author), University of Michigan-Ann Arbor.

Glossary

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Tuttle, R. H. 1986. Apes of the World. Noyes Publications, New Jersey.

Rodman, P.S., and Cant, J.G.H. 1984. Adaptations for Foraging in Nonhuman Primates. Columbia University Press, NY.

Wolfheim, J.H. 1983. Primates of the World: Distribution, Abundance, and Conservation.

University of Washington Press, Washington D.C.

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