White-handed gibbons are distributed throughout the tropical rainforests of Southeast Asia including Indonesia, Laos, Malaysia, Myanmar, and Thailand. Unfortunately, they are no longer found in China. White-handed gibbons have the largest latitudinal range of Hylobates species (Gron, 2010). (Gron, 2010)
Habitats in which white-handed gibbons are found include dipteropcarp forests, lowland and submontane rainforests, mixed deciduous bamboo forests, seasonal evergreen forests, and peat swamp forests (Gron, 2010). Home ranges are anywhere from 17 to 40 hectares in size (Savini, Boesch and Reichard, 2009). Their altitudinal range is limited to 1,200 meters. White-handed gibbons are a high canopy species and are rarely found in the understory (Gron, 2010). (Gron, 2010; Savini, et al., 2009)
White-handed gibbons are dichromatic in pelage. They wear either a dark coat, which may range from gray to black to brown, or a light coat of light cream color to light brown (Brockelman, 2004). The hairless face is surrounded by a ring of very short white or lightly colored fur; and the hands and feet are both white (Gron, 2010). Their elongated forelimbs, hands, and feet are adaptations for brachiation, which is their primary mode of travel through forest canopies (Vereecke, D'Aout, and Aerts, 2006). Lar gibbons do not have tails. Males are 43.5 to 58.4 cm long and females are 42.0 to 58.0 cm long. Males weigh 5.0 to 7.6 kg and females weigh 4.4 to 6.8 kg (Gron, 2010). (Brockelman, 2004; Gron, 2010; Vereecke, et al., 2006)
White-handed gibbons are mostly monogamous, living in groups of 2 to 6 members (Raemaekers and Raemaekers, 1985). Monogamy is seen with females who live in smaller home ranges where resources are denser, whereas polyandry is seen in females who live in larger home ranges and good resources are not numerous (Savini et al., 2009). (Raemaekers and Raemaekers, 1985; Savini, et al., 2009)
Females begin reproducing between 6 and 9 ears old, but are fully sexually mature at 9. They give birth to only one offspring about every 3.5 years and gestation lasts 7 months (Reichard, 1998). Weaning lasts about 20 months. (Columbian Park Zoo, 2012; Reichard, 1998)
Males do not directly care for offspring (Savini et al., 2009). Females care for young extensively. (Savini, et al., 2009)
Lar gibbons live, on average, 30 years in the wild and up to 44 years in captivity (Columbian Park Zoo, 2012). (Columbian Park Zoo, 2012)
Gibbons use vocalization for intraspecific communication. Normal duets are a function of territoriality; signaling to neighboring groups who pose a threat (Raemaekers and Raemaekers, 1985). Home ranges are defended during intergroup encounters and overlapping zones of ranges. Males sing together at range edges to chase away intruders and group defense becomes more important as home range size increases (Savini et al., 2009). White-handed gibbons are allo and auto-grooming animals. On average they spend ten hours a day allo-grooming. Auto-grooming is not significant proportion of daily activity. Allo-grooming probably serves more as a hygienic activity than a social function for this species (Reichard and Sommer, 1994). Fifteen and a half hours on average are spent in 'sleeping trees', from several hours before dusk until the following morning. This behavior reflects their adaptations to minimize predation risk. Vocal and physical interactions when retreating to sleeping trees are absent so as to avoid predator detection. Although this species is highly mobile, they do not gain safety during this stationary time period since they may fall asleep and not wake until a predator is upon them (Reichard, 1998) (Raemaekers and Raemaekers, 1985; Reichard and Sommer, 1994; Reichard, 1998; Savini, et al., 2009)
Lar gibbons communicate using term songs, which are combinations of solos and/or duets performed by bonded pairs. Calls are loud, long, and complex. Normal duets are loud songs delivered by a mated pair that is made up of an introductory call, a great call, and an interlude sequence. The introductory call is a series of notes by the pair, followed by the great call which begins with the female to which the male answers back, and finally the interlude sequence which is variable, but consists of male and female notes and the male's answering call. Offspring aren't usually involved, but female offspring may sometimes perform a great call with her mother. Duets occur between sunrise and noon, and peak at mid-morning. These calls average 11 minutes and can be heard up to one kilometer away (Raemaekers and Raemaekers, 1985). The sound of their voice is the most common way to find gibbon groups. They are also detectable from their movement through trees or by plain sight, but these are much less common (Savini, Boesch, and Reichard, 2009). (Raemaekers and Raemaekers, 1985; Savini, et al., 2009)
White-handed gibbons are largely frugivorous animals, eating ripe fruit from woody climbers and tropical trees (Whitington and Treesucon, 1991) (Savini et al., 2009). They also eat leafy plants, flowers, and insects, and are very selective feeders when it comes to fruit consumption. Fruits are tasted and either accepted or rejected based on ripeness. The same food sources are returned to multiple times during peak season to eat the ripest fruit each time (Whitington and Treesucon, 1991). Food sources are also shared in overlapping territory areas (Reichard, 1998). (Reichard, 1998; Savini, et al., 2009; Whitington and Treesucon, 1991)
Potential predators of white-handed gibbons include eagles, leopards, marbled cats, and pythons, though no act of predation has been observed. (Miller, 2002)
Given that white-handed gibbons are frugivores, they are most likely important for seed dispersal (Brockelman and Geissmann, 2008). Not much more is known about their ecosystem importance. (Brockelman and Geissmann, 2008)
White-handed gibbons do not provide any significant, positive economic importance that can be noted. Sometimes they are hunted for subsistence food by villagers. (Brockelman and Geissmann, 2008)
There is no negative economic impact of white-handed gibbons on humans.
White-handed gibbons are currently listed as an endangered species on the IUCN Red List. Their status is in part due to the flourishing illegal pet trade in Thailand, in which they are hunted, captured, traded, and exploited. The deforestation of habitat is also a threat and is becoming more of a problem. Protected conservation areas provide the greatest survival rates for populations of this species, although the ongoing agricultural development through these areas increases both fragmentation and access for hunters. (Brockelman and Geissmann, 2008; Gray, 2012)
Mariah Beaman (author), Northern Michigan University, John Bruggink (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
uses sound to communicate
Referring to an animal that lives in trees; tree-climbing.
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.
uses smells or other chemicals to communicate
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
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.
parental care is carried out by females
A substance that provides both nutrients and energy to a living thing.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats fruit
An animal that eats mainly plants or parts of plants.
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).
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
found in the oriental region of the world. In other words, India and southeast Asia.
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.
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.
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
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
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
young are relatively well-developed when born
Barelli, C., M. Heistermann, C. Boesch, U. Reichard. 2008. Mating patterns and sexual swellings in pair-living and multimale groups of wild white-handed gibbons, Hylobates lar. Animal Behaviour, 75: 991-1001.
Brockelman, W., T. Geissmann. 2008. "Hylobates lar" (On-line). Accessed April 02, 2013 at http://www.iucnredlist.org/details/10548/0.
Brockelman, W. 2004. Inheritance and selective effects of color phase in white-handed gibbons (Hylobates lar) in central Thailand. Mammalian Biology, 69: 73-80.
Columbian Park Zoo, 2012. "Lar or White Handed Gibbon" (On-line). Accessed April 27, 2013 at https://www.lafayette.in.gov/egov/docs/298271201804574.htm.
Gray, S. 2012. "Conservation difficulties for Hylobates lar: effects the illegal pet trade has on white-handed gibbons' behavioral health and successful rehabilitation" (On-line). Academia.edu. Accessed April 02, 2013 at http://www.academia.edu/1525036/Conservation_Difficulties_for_Hylobates_lar_Effects_the_Illegal_Pet_Trade_has_on_White-handed_Gibbons_Behavioral_Health_and_Successful_Rehabilitation.
Gron, K. 2010. "Lar gibbon Hylobates lar" (On-line). Primate Info Net. Accessed February 12, 2013 at http://pin.primate.wisc.edu/factsheets/entry/lar_gibbon.
Miller, L. 2002. Eat or be eaten: predator sensitive foraging among primates. Cambridge, UK: Cambridge University Press.
Raemaekers, P., J. Raemaekers. 1985. Long-range interactions between groups of gibbons (Hylobates lar). Behaviour, 95: 26-44.
Reichard, U. 1998. Sleeping sites, sleeping places, and presleep behavior of gibbons (Hylobates lar). American Journal of Primatology, 46: 35-62.
Reichard, U., C. Barelli. 2008. Life history and reproductive strategies of Khao Yai Hylobates lar: implications for social evolution in apes. International Journal of Primatology, 29: 823-844.
Reichard, U., V. Sommer. 1994. Grooming site preferences in wild white-handed gibbons (Hylobates lar). Primates, 35: 369-374.
Reichard, U., V. Sommer. 1997. Group encounters in wild gibbons (Hylobates lar): agonism, affiliation, and the concept of infanticide. Behaviour, 134: 1135-1174.
Savini, T., C. Boesch, U. Reichard. 2009. Varying ecological quality influences the probability of polyandry in white-handed gibbons (Hylobates lar) in Thailand. Biotropica, 41: 503-513.
Smith, P., T. Yuill, R. Buchanan, J. Stanton, V. Chaicumpa. 1969. The gibbon (Hylobates lar): a new primate host for Herpesviras hominis. I. A natural epizootic in a laboratory colony. The Journal of Infectious Diseases, 120: 292-297.
Vereecke, E., K. D'Aout, P. Aerts. 2006. Locomotor versatility in the white-handed gibbon (Hylobates lar): a spatiotemporal analysis of the bipedal, tripedal, and quadrupedal gaits. Journal of Human Evolution, 50: 552-567.
Whitington, C., U. Treesucon. 1991. Selection and treatment of food plants by white-handed gibbons (Hylobates lar) in Khao Yai National Park, Thailand. National History Bulletin of the Siam Society, 39: 111-122.