Lar Gibbon (Hylobates lar)
Other names: H. albimana, H. longimana, H. variegates, H.
varius, common gibbon, Lar Gibbon, White-Handed Gibbon; withandgibbon
(Dutch); gibbon à mains blanches, gibbon lar (French); gibbon de manos blancas
(Spanish); lar, vanlig gibbon, vithandad gibbon (Swedish); H. l. carpenteri:
Carpenter's lar; H. l. entelloides: central lar; H. l. lar: Malaysian lar; H. l.
vestitus: Sumatran lar.
The sub specific status of the Yunnan lar, H. l. yunnanensis, is doubtful as it is likely synonymous with H. l. carpenteri and as such, is not considered as a subspecies here (Geissmann 1995; Brandon-Jones et al. 2004; Groves & Geissmann pers comm. cited in Geissmann 2007). Some publications still do consider H. l. yunnanensis a valid subspecies, however all of this may be moot as the populations which may have made up H. l. yunnanensis are in all likelihood extinct (Geissmann 2008). All subspecies need to be better defined and are not highly distinct (Brockelman & Geissmann 2008).
Lar Gibbons weigh on average between 5.0-7.6 kg (11.0-16.8 lb)(M) and 4.4-6.8 kg (9.7-15.0 lb) (F). Head and body lengths range from 43.5-58.5 cm (17.1-23.0 in) (M) and 42.0-58.0 cm (16.5-22.8 in) (F) (Roonwal & Mohnot 1977). Like all apes, lar gibbons have no tail and also possess small Ischia callosities as well as long arms suited for brachiation (Ankel-Simons 2007).
Pelage is creamy, brown, or black in both sexes and at all ages (Roonwal & Mohnot 1977; Mootnick 2006; Bartlett 2009). Adults have a ring around the hairless face (less apparent in lighter individuals) and have white feet and hands that contrast with the rest of the body (Marshall & Sugardjito 1986; Groves 2001; Mootnick 2006; Ankel-Simons 2007; Bartlett 2009). Individuals are either light or dark in overall colour (often called light and dark phases), with light individuals having buff or creamy pelage, and dark individuals with brown or black pelage (Groves 2001). The deciding factor whether a lar gibbon is dark or light is simple genetic inheritance from its parents, in which the dark form is the dominant allele (Brockelman 2004). The proportion of dark to light individuals varies in lar gibbons, with some populations being mostly light and others being mostly dark and with various proportions in-between, often varying greatly between populations (Marshall & Sugardjito 1986; Brockelman 2004). Mating is random with respect to pelage colour (Brockelman 2004).
H. l. carpenteri are long-haired and almost black or brownish charcoal in the dark form and are creamy white or white-buff in the light form (Groves 2001; Mootnick 2006). H. l. entelloides are black or black-brown in the dark form and honey-coloured in the light form with darker legs (Groves 2001; Mootnick 2006). H. l. lar are medium brown or dark chocolate brown in the dark form with a lighter torso and darker legs (Groves 2001; Mootnick 2006). This subspecies is creamy in the light form (Groves 2001). H. l. vestitus are always light with no dark form and are typically light brown, with a buff back, pale lower back and a brown head, ventrum and limbs (Marshall & Sugardjito 1986; Groves 2001). However, due to variation across their distribution, if a specific lar gibbon's place or origin is unknown, it is difficult to assign it sub specifically based on morphology (Geissmann 1995). Morphological differences between subspecies need to be further documented (Brandon-Jones et al. 2004).
Lar Gibbons are adapted for arboreal locomotion and usually move through their environment using brachiation, but also through other forms of movement (Roonwal & Mohnot 1977; Vereecke et al. 2006). These include walking (bipedal, tripedal, and quadrupedal), hopping, running (bipedal, tripedal, and quadrupedal), climbing, swinging, bridging and leaping (Baldwin & Teleki 1976; Carpenter 1976). Lar Gibbons are also capable of rapid terrestrial movement using 7 types of gait even though they are adapted for arboreal locomotion (Vereecke et al. 2006).
In captivity, Lar Gibbons have lived up to around 50 years of age (Weigl 2005).
Hylobates lar | Hylobates lar carpenteri | Hylobates lar
lar | Hylobates lar vestitus | Hylobates lar entelloides | Hylobates lar
Lar Gibbons are mainly found in Southeast Asia and in a small portion of South Asia. They have the greatest north-south range of any of the gibbons (Bartlett 2007). The species is found in Indonesia, Laos, Malaysia, Myanmar and Thailand (Brandon-Jones et al. 2004). Lar gibbons are probably extinct in China but if they still exist, they would only be found in Southwest Yunnan, their former range (Brandon-Jones et al. 2004; Brockelman & Geissmann 2008; Geissmann 2008). Moving south from southwest Yunnan, Lar Gibbons are found in the majority of Thailand excepting the north-eastern areas of the country. The range extends south through southern and eastern Myanmar but only east of the Salween River (Brockelman & Geissmann 2008). They are found through the Malay Peninsula except for a discontinuity in their distribution between the Perak and Muda Rivers, very roughly near the Thai-Malay border (Brockelman & Geissmann 2008). Lar gibbons also exist west of the Mekong River in north-western Laos and in northern Sumatra (Brandon-Jones et al. 2004; Brockelman & Geissmann 2008). Sub specifically, H. l. lar are found in peninsular Malaysia and possibly Thailand. H. l. carpenteri is found in Myanmar, west Laos, and north Thailand. H. l. entelloides is found in southeast Myanmar, and in central and south Thailand (Brandon-Jones et al. 2004). In Indonesia, H. l. vestitus is found over the northern third of the island of Sumatra (MacKinnon 1984; Brandon-Jones et al. 2004; Brockelman & Geissmann 2008).
In Thailand, there are probably between 15,000-20,000 lar gibbons (Geissmann 2007).
In general, Lar Gibbons are found in lowland dipterocarp forest, hill dipterocarp forest, and upper dipterocarp forests, including primary lowland and submontane rainforest, mixed deciduous bamboo forest, and seasonal evergreen forests, but are not usually found higher than 1200 meters above sea level (Chivers 1972; Ellefson 1974; Caldecott 1980; Palombit 1992; Ungar 1996; Reichard & Sommer 1997; Brockelman et al. 1998; Yimkao & Srikosamatara 2006; Bartlett 2009). Lar Gibbons are also found in peat swamp forest (Norhayati et al. 2004).
Perhaps the most important study site of Lar Gibbons is at Khao Yai, Thailand, Northeast of Bangkok, home to many studies (some long-term) since the 1970's (Brockelman et al. 1998; Bartlett 2009). The vegetation type at this site is mostly seasonally wet evergreen rainforest (Brockelman et al. 1998; Bartlett 2009). Three seasons are experienced in this part of Thailand; a cool season (November to February), a hot season (March-May) and a wet season (June-October) (Bartlett 2009). Annual rainfall at this site averages between 200 and 300 cm (78.7 and 118.1 in) (mostly falling June-September) and daytime high temperatures usually average between 25°C and 30°C (77°F and 86°F) year-round. The coldest lows are usually no colder than 10°C (50°F) (Tangtham 1991 cited in Bartlett 2009; Bartlett 2009).
Lar gibbons are usually found high in the canopy and are rarely found in the understory (Ungar 1996). At Khao Yai, the average height of feeding trees was 23.7 meters (77.8 ft) (Bartlett 2009).
Lar Gibbons eat a large variety of foods, especially fruit, including figs and other small, sweet fruits, liana fruit, tree fruit and berries but also young leaves, buds & flowers, new shoots, vines, vine shoots, insects including mantids and wasps, and even birds' eggs (Carpenter 1940; Ellefson 1974; Raemaekers 1979; MacKinnon & MacKinnon 1980; Ungar 1995; Palombit 1997; Yimkao & Srikosamatara 2006; Bartlett 1999; 2009). They are known to eat parts of over 100 species of plants (Bartlett 1999; 2009). In general, when data is combined among study sites, the lar gibbon diet includes fruit (66%), leaves (24%), flowers (1%), and insects (9%) although in individual studies there can be some significant variation by locality (see review in Bartlett 2007; Bartlett 2007). Figs often make up a large proportion of the diet, on average around 27%, but sometimes up to half of the total foods eaten (Palombit 1997; Bartlett 2007). Feeding on figs increases during times that other preferred resources are scarce (Bartlett 1999). Food transfer between Lar Gibbons has been seen often accompanied by begging of one animal for food from another (Nettelbeck 1998). Most leaves that are eaten are young. One method that Lar Gibbons drink water is from tree holes by cupping their hands (Bartlett 1999). Diet can vary quite a bit with the seasons. For example, at Khao Yai, non-fig fruits dominated in the diet through the year excepting November and December. At this study site, flowers are most available during the cool season, while ripe fruit is most abundant during the hot and wet seasons. At this study site, ripe fruit is preferred when available, with the variability of the diet increasing when ripe fruit is less available during the cool season. However, fruit including figs never fell below 50% of the diet year-round (Bartlett 2009). Food competition may exist between Lar Gibbons and Pigtail Macaques (Macaca nemestrina) as the two species have been seen foraging near one another and sometimes interacting (Whitington 1992). Feeding competition between Lar Gibbons and Long-Tailed Macaques (M. fascicularis) and Dusky Leaf Monkeys (Trachypithecus obscurus) has also been seen (Ellefson 1974). Lar Gibbons compete with sympatric siamangs (Symphalangus syndactylus), the presence of which usually causes conflict and probably reduces the foraging success of Lar Gibbons (Palombit 1996). Diurnal Lar Gibbons in Thailand are active for an average of 8.7 hours per day, leaving their sleeping sites right around sunrise and entering sleeping tress an average of 3.4 hours before sunset (Bartlett 2009). On average, Lar Gibbons spend their days feeding (32.6%), resting (26.2%), travelling (24.2%), in social activities (11.3%), vocalizing (4.0%) and in inter-group encounters (1.9%), although actual proportions of activities can change significantly over the course of the year (Bartlett 2009). Daily, if the morning is clear before dawn, an adult male will solo call, usually from its sleeping tree. At sunrise, all group gibbons will awaken, then defecate and urinate while hanging from a branch. Usually, the group will then move to a feeding tree. There is normally a duet call among the adult pair before noon and the rest of the day is spent alternating between feeding and travelling to new trees to feed. With seasonal reductions in the amount of available fruit, feeding time increases and, correspondingly, less time is spent in social activities (Bartlett 2009). A group pause for about an hour of rest and social activities usually occurs each day (Bartlett 2009). During the cool season, Lar Gibbons can often be found for up to several hours a day in big fig trees (Bartlett 2009). Average home range is 0.4 km² (0.15 mi²), with a daily path length of 1.4 kilometres (0.87 mi) although there is considerable variation among study sites (Bartlett 2007). Daily path length tends to increase with increased fruit availability (Bartlett 1999). Group progressions at some locations are usually led by the adult male, while at other sites females may do so, and coordinate group movements as well (Yimkao & Srikosamatara 2006; Barelli et al. 2008a). Within the home range is a territory defended from other groups averaging around 76% of the home range (Bartlett 2007). The home ranges of different groups often overlap, sometimes extensively (Ellefson 1974; Reichard & Sommer 1997; Bartlett 1999). Sleeping trees are not manipulated and group members usually sleep one to a tree nearby each other. Often the tallest trees available are chosen for sleeping and lar gibbons try to avoid notice when moving to sleeping sites, possibly as a way of reducing predation (Reichard 1998). Often, sleeping trees are located on steep slopes or on cliffs (Yimkao & Srikosamatara 2006).While the specific composition of the primate community varies across the distribution of the Lar Gibbon, the species can be found living in sympatry with several other primates and apes, including orang-utans (Pongo pygmaeus), siamangs (S. syndactylus), Pileated Gibbons (Hylobates pileatus), Purple-Faced Langurs (Trachypithecus sp.), Thomas's Langur (Presbytis thomasi), slow loris (Nycticebus coucang), and several macaque species (Macaca sp.) (Ellefson 1974; Geissmann 1991; Palombit 1992; Ungar 1995; Palombit 1996; Bartlett 1999; Yimkao & Srikosamatara 2006).
Sexually, they are similar to other gibbons. Mating occurs in every month of the year, but most conceptions occur during the dry season in March, with a peak in births during the late rainy season, in October. On average, females reproduce for the first time at about 11 years of age in the wild, much later than in captivity. Gestation is six months long on average, and pregnancies are usually of a single young. Young are nursed for approximately two years, and full maturity comes at about eight years. The life expectancy of the lar gibbons in the wild is about 25 years.
Predators and Threats:
There are a number of potential predators of adult or infant Lar gibbons. These may include Clouded Leopards (Neofelis nebulosa), Marbled Cats (Pardofelis marmorata), Asian Golden Cats (Catopuma temmincki), Leopard Cats (Prionailurus bengalensis) Tigers (Panthera tigris), Leopards (Panthera pardus), Pythons (Python sp.), Hawk Eagle species (Spizaetus sp.), Black Eagles (Ictinaetus malayensis), and Crested Sepent Eagles (Spilornis cheela) (Reichard 1998; Uhde & Sommer 2002). White-Bellied Sea eagles (Haliaeetus leucogaster) are also capable of taking a Lar Gibbon (Ellefson 1974). Lar Gibbons may mob and chase off potential predators (Reichard 1998; Uhude & Sommer 2002).
The major threat to this species is hunting (having replaced
even forest clearance as the top threat); they are hunted both for subsistence
food use and for the pet trade. Hunting pressure varies across the range, but
takes place even within protected areas. Much of the hunting is done by
villagers exploiting Aquilaria spp. trees prized for their aromatic wood, and
other forest products (W. Brockelman pers. comm.).
Construction of roads through protected areas (for example, the Security Highway through Nam Poyi in Lao PDR, the north-south highway in Peninsular Malaysia) may also pose a threat since it promotes forest clearance and strip development, possibly increases fragmentation, and increases access by hunters into protected areas. Ongoing localized forest loss due to shifting agriculture and commercial plantations of palm oil poses a threat. On northern Sumatra, most of the lowland forests have been logged out and the threat of Ladia Galaskar, a network to link the west and east coasts of Aceh province, means that much of the remaining forest is at risk.
Like all gibbons, is a nationally protected species in
all the countries across its range, and is listed under CITES Appendix I. In
most of its range it is confined to protected conservation areas (for example in
Thailand, where no significant
populations survive outside of protected areas). However, in most countries,
these areas are not well patrolled, even if they are well managed for tourism.
There is an urgent need for improved protection of these areas, ideally
involving local communities that should benefit from as well as participate in
management. Illegal use of forest products, as well as poaching, is common in
most protected areas. Inadequate management and protection, rather than forest
destruction, are the main long-term threats and conservation efforts must seek
to identify the hunters and incorporate them into new management priorities.
Further survey work is needed to determine current population numbers within protected areas across the range. One such priority area is southwest Yunnan, where it is unclear whether the species still survives (W. Brockelman pers. comm.).