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Hylobates agilisagile gibbon

By Jennifer Kuester

Ge­o­graphic Range

Gib­bons are found through­out the trop­i­cal rain­forests of South and South­east Asia. Agile gib­bons, Hy­lo­bates ag­ilis, are found in Thai­land, In­done­sia, and Malaysia.

Habi­tat

Hy­lo­bates ag­ilis is found in the trop­i­cal rain­forests of Thai­land, Malaysia, and In­done­sia. They live in the upper canopy of the for­est, feed­ing on fruits, leaves, and in­sects. Mem­bers of Hy­lo­bates spend most of their lives in the trees, and rarely de­scend to the ground.

Phys­i­cal De­scrip­tion

Lesser apes in the fam­ily Hy­lo­bati­dae are gen­er­ally small. The av­er­age weight of H. ag­ilis is 5.4 kg for fe­males and 5.8 kg for males. Agile gib­bons come in a va­ri­ety of dif­fer­ent col­ors, in­clud­ing black, brown, light tan and red­dish-brown. Both sexes have white eye­brows. Males and fe­males can be eas­ily dis­tin­guished by the white eye­brows and cheeks pos­sessed by the males.

Gib­bons lack tails. Hy­lo­bates ag­ilis, like other gib­bons, has ex­tremely long arms and fin­gers. This adap­ta­tion aides in brachi­a­tion, the prn­ci­ple mean of lo­co­mo­tion for these an­i­mals. Brachi­a­tion con­sists of hang­ing from branches and swing­ing from tree to tree.

  • Sexual Dimorphism
  • male larger
  • Range mass
    4 to 6 kg
    8.81 to 13.22 lb

Re­pro­duc­tion

Hy­lo­bates ag­ilis forms monog­a­mous bonds. Mated pairs stay to­gether until one of them dies.

Hy­lo­bates ag­ilis be­comes sex­u­ally ma­ture around the age of 8 years. The ges­ta­tion pe­riod is about seven months. These an­i­mals give birth to a sin­gle off­spring per preg­nancy, and a mated pair can pro­duce five to six off­spring dur­ing their re­pro­duc­tive life­time. The in­ter­birth in­ter­val for H. ag­ilis is around forty months.

  • Breeding interval
    The interbirth period for H. agilis is around forty months.
  • Breeding season
    These animals do not have a strict breeding season.
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    7 months
  • Average age at sexual or reproductive maturity (female)
    8 years
  • Average age at sexual or reproductive maturity (male)
    8 years

Most fe­male gib­bons nurse and care for their off­spring until the off­spring are about two years old. Off­spring re­main with their par­ents until they reach sex­ual ma­tu­rity, around eight years, they then dis­perse from their natal group.

Males also par­tic­pate in parental care in this monog­a­mous species. Males groom off­spring, and help to de­fend them.

  • 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

The re­ported lifes­pan in cap­tiv­ity for these lesser apes is 44 years. Wild an­i­mals prob­a­bly do not live as long.

Be­hav­ior

The av­er­age group size for H. ag­ilis is four in­di­vid­u­als. The group usu­ally con­sists of the male and fe­male mated pair, an in­fant, and a ju­ve­nile.

Gib­bons ex­hibit two unique forms of be­hav­ior: monogamy and "singing". When an in­di­vid­ual H. ag­ilis dis­perses from its natal group (when it has reached sex­ual ma­tu­rity), it finds a mate that it will spend the rest of its life with. These monog­a­mous bonds are im­por­tant for rais­ing young and for de­fend­ing the pair's ter­ri­tory. Hy­lo­bates ag­ilis de­fend a ter­ri­tory by "singing". In the early morn­ing, great calls can be heard through­out the upper canopy. These singing bouts are often duets and are a way of claim­ing home ter­ri­tory. When singing is not enough to keep in­trud­ers away, both male and fe­male gib­bons will chase the in­truder away.

Com­mu­ni­ca­tion and Per­cep­tion

As in all pri­mates, com­mu­ni­ca­tion in this species is com­plex and in­volved sev­eral dif­fer­ent modal­i­ties.

As men­tioned in the "Be­hav­ior" sec­tion, above, these an­i­mals are highly vocal, and use great call vo­cal­iza­tions to de­fend their ter­ri­to­ries from other mated pairs.

Tac­tile com­mu­ni­ca­tion is also im­por­tant, be­tween mates, and be­tween par­ents and their off­spring. Tac­tile com­mu­ni­ca­tion in­volves groom­ing, mat­ing, play and some­times ag­gres­sion.

In ad­di­tion to vocal and tac­tile forms of com­mu­ni­ca­tion, these an­i­mals use fa­cial ex­pres­sions, ges­tures, and body pos­tures to com­mu­ni­cate with con­specifics.

  • Other Communication Modes
  • duets

Food Habits

Hy­lo­bates ag­ilis con­sumes large amounts of fruits. Like other gib­bons, these an­i­mals are pri­mar­ily fru­giv­o­rous. Agile gib­bons have also been ob­served eat­ing a va­ri­ety of other foods, in­clud­ing leaves, flow­ers, and in­sects. Due to their ac­tive lifestyle, it is nec­es­sary for them to eat food rich in calo­ries. Fruits have a high caloric con­tent.

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • fruit
  • flowers

Pre­da­tion

De­tails on pre­da­tion in this species are not avail­able. How­ever, snakes and rap­tors are prob­a­bly the great­est threats to these an­i­mals. Be­cause of their highly ar­bo­real lifestyle, many po­ten­tial preda­tors are not likely to have ac­cess to these an­i­mals.

Ecosys­tem Roles

As these an­i­mals are not likely to be an im­por­tant source of food for other an­i­mals, their great­est role in the ecosys­tem is prob­a­bly seed dis­per­sal for the fruits they eat.

  • Ecosystem Impact
  • disperses seeds

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Hy­lo­bates ag­ilis is not an im­por­tant eco­nomic re­source for hu­mans. These an­i­mals are some­times hunted for food, and they are il­le­gally cap­tured for the pet trade. Poach­ing is a threat to H. ag­ilis, for an­i­mals that are caught often die in trans­port from mis­han­dling. Il­le­gal poach­ing for meat and the pet trade are con­tribut­ing fac­tors in the de­clin­ing num­bers of H. ag­ilis.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There is no known neg­a­tive eco­nomic ef­fect of this species on hu­mans.

Con­ser­va­tion Sta­tus

Hy­lo­bates ag­ilis is listed by IUCN as an en­dan­gered species. Due to mas­sive de­for­esta­tion, their habi­tat is rapidly de­creas­ing. This loss of habi­tat due to log­ging and agri­cul­tural de­mands is the main threat to gib­bon species. Con­ser­va­tion mea­sures have been taken, such as re­serve game parks and breed­ing pro­grams in zoos. Un­for­tu­nately, these mea­sures are not enough, and more in­tense con­ser­va­tion ef­forts must be ini­ti­ated in order to en­sure the sur­vival of these species.

Con­trib­u­tors

Nancy Shef­ferly (ed­i­tor), An­i­mal Di­ver­sity Web.

Jen­nifer Kuester (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor), Mu­seum of Zo­ol­ogy, 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.

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.

year-round breeding

breeding takes place throughout the year

Ref­er­ences

"Agile Gib­bon (Hy­lo­bates ag­ilis)" (On-line). Ac­cessed No­vem­ber 10, 1999 at http://​members.​tripod.​com/​uakari/​hylobates_​agilis.​html.

Leighton, D. 1987. "Gib­bons: Ter­ri­to­ri­al­ity and Monogamy". Pp. 135-144 in B Smuts, D Ch­eney, R Sey­farth, R Wrang­ham, T Struh­saker, eds. Pri­mate So­ci­eties. Chicago: Uni­ver­sity of Chicago Press.

Nowak, R. 1999. Walker's Mam­mals of the World, Sixth Edi­tion. Bal­ti­more and Lon­don: The Johns Hop­kins Uni­ver­sity Press.

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

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Classification

Classification

  • Kingdom Animalia animals
  • Phylum Chordata chordates
  • Subphylum Vertebrata vertebrates
  • Class Mammalia mammals
  • Order Primates primates
  • Family Hylobatidae gibbons and lesser apes
  • Genus Hylobates gibbons
  • Species Hylobates agilis agile gibbon