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Lar gibbon group

Page history last edited by 530257 10 years, 4 months ago

 

   Lar gibbon  (Hylobates lar)

 

Taxonomy

 

Kingdom – Animalia

Phylum – Chordata

Class – Mammalia

Order – Primates

Family – Hylobatidae

Genus – Hylobates

Species – Hylobates Lar

 

 

 

 

 

 

 

 

Geographical distribution

 

The range of the Lar Gibbon extends from southwest China and eastern Myanmar to Thailand and Burma, Laos, Malay Peninsula and Sumatra. They live in a wide range of habitats ranging from evergreen and semi-evergreen to mixed evergreen-deciduous forest. In recent years, the range of the Lar Gibbon has been reduced and fragmented, especially on the continent. At present, they are thought to be extirpated in China. The gibbon genus is highly allopatric, usually separated by large rivers (Brockelman, W. & Geissmann, T. 2008)

 

Morphology

 

Lar Gibbons show very slight sexual dimorphism with the females being smaller, both in weight and overall body length. The average male Lar gibbon weighs 5-7.6kg with the female weighing on average, 4.4kg to 6.8kg.  Male body length will range from 43.5-58.5cm, with the female to some extent smaller at 42-58cm (Roonwal & Mohnot 1977). The Lar gibbon has no functional tail, making it an ape. It also has long arms and grasping hands that are suited for brachiation, which is their main form of locomotion. Others include walking (bipedal, tripedal and quadrupedal), hopping, running, climbing, swinging and leaping (Baldwin & Teleki 1976; Carpenter 1976).

Pelage (fur) is creamy and brown/black at all ages in both sexes (Roonwal & Mohnot 1977; Mootnick 2006; Bartlett 2009). Adults possess a ring of white hair around their black face and have white feet and hands that form a contrast between the rest of their body (Marshall & Sugardjito 1986; Groves 2001; Mootnick 2006; Ankel-Simons 2007; Bartlett 2009). The dense and fluffy fur not only keeps the Lar gibbon cool in warmer temperatures but also makes the individual appear larger to predators. The palms of their hands and the soles of their feet are free of fur (Anon1 2008).

 

Diet and feeding behaviour

 

The Lar gibbon’s diet can vary with the seasons and they eat a wide variety of foods. They are considered frugivorous but also eat; shoots and young leaves, buds, flowers, insects and even birds eggs (Carpenter 1940; Ellefson 1974; Raemaekers 1979; MacKinnon & MacKinnon 1980; Ungar 1995; Palombit 1997; Yimkao & Srikosamatara 2006; Bartlett 1999; 2009). Lar gibbons are known to eat over 100 different species of plant (Bartlett 1999; 2009). Studies have shown that fruit can make up to 66% of the Lar gibbon’s diet and that when other preferred foods are scarce they will increase their consumption of figs, at times this can be up to 50% (Palombit 1997; Bartlett 2007).

Studies have also found that the Lar gibbons will eat ripe and unripe fruit species and tend to swallow whole, any food that is small enough or the right shape, because of this many plant species rely on the Lar gibbon for dispersal of seeds (C Whitington and U Treesucon 1991).

Brachiation can be seen as an adaptation for the Lar gibbon as this style of motion allows them to reach the edge of the tree canopy, meaning they can reach most of the food available. Other adaptations are high cusps on their back teeth which help to grind plant matter, and a gut adapted for a folivorous diet. Food has been seen to be transferred between Lar gibbons often by one begging food from another. The Lar gibbon’s water supply comes from tree holes and they drink water by supping their hands or sucking their own fur after a rain storm.

 

Social structure and behaviour

 

Lar gibbons are diurnal and are active in the day. In the wild Lar gibbons generally live in monogamous pairs and their social organisation is dominated by the breeding pair, along with their offspring, with family troops ranging from 2-6 members. Although that is the norm studies have seen that there are some sites that include multi male/female groups and that some females live in several different groups within their life. The change of individual pair bonds can be common, as a result of death of one of the adults, desertion or disappearance. When juveniles reach sexual maturity (5-7 years) they are excluded from the family unit. Group members sleep in trees, often the tallest that are close to steep slopes or cliffs, this may be to avoid predation.

The Lar gibbon is arboreal and rarely goes onto the ground, as a result, brachiation constitutes around 90% of their means of locomotion.   

Three social behaviours exist within the Lar gibbon group; grooming, play (wrestling, slapping and biting) and aggression. With grooming being the most commonly observed. Allogrooming seems to be more for the sake of hygiene than social interaction. In general juvenile, Lar gibbons play more than adults. Aggression within the group is thought to be rare and there is no one individual leader within a Lar gibbon group.

Lar gibbons display territoriality, and meetings between groups can be both friendly and physical with most disputes only involving the males. Disputes or meeting of groups usually happen at territory boundaries when the two groups have visual contact with each other and usually last up to an hour at most. The nature of these interactions may be related to the kin relations between neighbouring groups. There is however evidence that wounds obtained due to territorial aggression have resulted in death (Palombit 1997). A troop of Lar gibbons can occupy a territory of 30 -100 acres which is marked mainly through vocalisation. There are currently up to seven known vocalisation note types for the Lar gibbon, these basic types are often made into longer phrases. Lar gibbons call in many different contexts, the main being a ‘contact’ call, this is to let others know of their whereabouts and of the other group members. Lar gibbons often call in duets as well, this a structured vocalisation made by the mating pair of the group. Male and females also emit solo calls and all Lar gibbons call when they are disturbed to raise the alarm of a predator or of a conflict in the home range area.

 

Behavioural Analysis

 

Discrete Behaviour

 

Discrete Behavioural Category

Description

Broad Behavioural Category

Swinging

Using arms, legs and tail to swing from one point of leverage to another.

Locomotion

Ground movement

Quadra pedal  or bipedal movement along the floor.

Locomotion

Sitting

Bodyweight on rump with back vertical.

Rest

Hanging

Attached to a horizontal substrate via limbs and/or tail.

Rest

Clasping

Attached to a vertical substrate via limbs and/or tail.

Rest

Observing

Observing/tracking of specific objects.

Observation

Scratching

Massaging body/limbs/head with one or more limbs.

Body care

Hidden from view

Subject is out of line of sight of observer.

Rest

Vocalization

Producing noise from mouth cavity.

Social

Opening mouth

Opening mouth cavity but not producing noise.

Rest

Grooming

Using teeth and fingers/toes to clean fur.

Body care

Defecating

Expelling of waste from anus and/or penis/vaginal area.

Excretion

Climbing

Using limbs and/or tail to move up a vertical substrate.

Locomotion

Eating

Putting food items into mouth cavity, chewing and/or swallowing.

Consumption

Drinking

Consuming water using limbs or lowering body to source of water.

Consumption

Head movement

Moving head along the 3 axis.

Observation

 

Total Observation Period of both Lar gibbons: 14:23 – 14:53 

Prevailing weather conditions: sunny, warm and dry.

 

Subjects: 

The group consisted of two Lar gibbons:

Subject 1 - aged 25 years. Female (Ella)

Subject 2 - aged 16 years. Male (Nike)

  

Method:

 

We observed both gibbons at the same time for 30 minutes, noting down their discrete behaviour and location in turn once every 30 seconds. Ella was recorded once a minute on the minute and Nike once a minute on the 30 seconds.

 

Lar Gibbon Enclosure

 

Aerial Map

Photo of front of enclosure

 

 

Subject 1: Ella

 

Time

Discrete Behaviour

Location in enclosure.

14:24:00

Out of sight.

Backroom.

14:50:00

Hanging from ropes with hands clasping the rope above and feet clasping the rope below.

Cage 2, Area 4, Upper. Hanging from ropes.

14:53:00

Sitting on elevated branch.

Cage 2, Area 1, Lower, On branch at the front of the enclosure.

 

 

 

Subject 2: Nike

 

Time

Discrete Behaviour

Location in enclosure.

14:23:30

Sitting on elevated branch.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:24:30

Sitting on elevated branch clasping the cage with left hand and both feet. Moving head from side to side.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:25:30

Sitting on elevated branch clasping the cage with left hand and both feet.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:28:30

Sitting on elevated branch clasping the cage with left hand and both feet. Opened mouth.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:29:30

Sitting on elevated branch. Scratching head with left hand.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:30:30

Sitting on elevated branch. Hands on lap. (No response to humans taking photos of him.)

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:31:30

Sitting on elevated branch. Hands on lap.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:33:30

Sitting on elevated branch clasping the cage with both feet and both hands. Upper limbs are crossed. (No response to humans calling for him.)

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:35:30

Sitting on elevated branch clasping the cage with both feet and both hands. Upper limbs are crossed.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:37:30

Sitting on elevated branch clasping the cage with both feet and both hands. Upper limbs are crossed. (No response to humans waving at him.)

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:38:30

Sitting on elevated branch clasping the cage with both feet and both hands. Upper limbs are crossed. (Human visitors think he looks 'sad'.)

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:39:30

Sitting on elevated branch clasping the cage with both feet and both hands. Upper limbs are crossed.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:42:30

Sitting on elevated branch clasping the cage with left hand and both feet.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:43:30

Sitting on elevated branch clasping the cage with both feet.

Cage 2, Area 1, Lower. On branch at front of enclosure.

14:44:30

Hanging from the front of the cage with left arm and both feet clasping the cage. Scratching left upper arm with right hand.

Cage 2, Area 1, Lower. Hanging from the front wall of cage.

14:45:30

Fast swinging movement to backroom using the ropes in the upper part of the cage to swing from.

Cage 2, Area 3, Upper.

14:46:30

Out of sight.

Backroom with no public access for observation.

14:52:30

Out of sight.

Backroom with no public access for observation.

 

 

 

Discussion

 

Prior to the commencement of the observation period, both Lar gibbons were seen to use more areas of the enclosure than they did during the observation period. Both of the gibbons only used 3 areas of the enclosure each. Inside the enclosure were examples of previous enrichment initiatives including dog toys which laid unused on the floor. They spent a large amount of time out of sight in the backroom which may be due to them having food there or perhaps they were becoming stressed by the Siamang gibbons (Symphalangus syndactylus) which were calling constantly during the observation period and were in fairly close proximity to their enclosure. When in sight both gibbons were fairly inactive and both seemed to favour one particular elevated piece of wood at the front of the enclosure, from which they could look out at the area outside of the enclosure. Subject 2 spent 70% of its time sitting on the same piece of wood. Subject 1 was older than Subject 2 and had not spent as much of her life at the park as Subject 2 had. She therefore may not be as habituated to human presence and so this may explain why she spent the majority of her time out of sight. Neither Lar gibbon spent any time on the ground and so were displaying their natural arboreal behaviour. Both gibbons appeared to be in a healthy condition.

 

References

 

http://www.iucnredlist.org/apps/redlist/details/10548/0

Anon1 2008- Available from http://www.honoluluzoo.org/whitehanded_gibbon.htm [Accessed 26/11/2010]

Ankel-Simons F. 2007. Primate Anatomy: an introduction, 3rd Edition. San Diego: Elsevier Acad Pr. 724 p.

`Baldwin LA, Teleki G. 1976. Patterns of gibbon behavior on Hall's Island, Bermuda. Gibb Siam 4:21-105.

Barelli C, Boesch C, Heistermann M, Reichard UH. 2008a. Female white-handed gibbons (Hylobates lar) lead group movements and have priority of access to food resources. Behaviour 145(7):965-81.

Bartlett TQ. 1999. Feeding and ranging behavior of the white-handed gibbon (Hylobates lar) in Khao Yai National Park, Thailand. PhD dissertation, Washington University, St. Louis. 193p.

Bartlett TQ. 2003. Intragroup and intergroup social interactions in white-handed gibbons. Int J Primatol 24(2):239-59.

Bartlett TQ. 2007. The Hylobatidae: small apes of Asia. In: Campbell CJ, Fuentes A, MacKinnon KC, Panger M, Bearder SK, editors. Primates in perspective. New York:Oxford U Pr. p274-89.

Bartlett TQ. 2009. The gibbons of Khao Yai: seasonal variation in behavior and ecology. Upper Saddle River (NJ):Pearson Prentice Hall. 170p.

Brockelman, W. & Geissmann, T. 2008.Hylobates lar. In: IUCN 2010. IUCN Red List of

Carpenter CR. 1940. A field study in Siam of the behavior and social relations of the gibbon (Hylobates lar). Comp Psychol Mono 16(5):1-212.

Carpenter CR. 1976. Suspensory behavior of gibbons Hylobates lar. Gibb Siam 4:1-20.

Ellefson JO. 1974. A natural history of white-handed gibbons in the Malayan peninsula. Gibb Siam 3:1-136.

Groves CP. 2001. Primate taxonomy. Washington, D.C.:Smithsonian Institution Pr. 350p.

MacKinnon JR, MacKinnon KS. 1980. Niche differentiation in a primate community. In: Chivers DJ, editor. Malayan forest primates: ten years' study in tropical rain forest. New York:Plenum Pr. p167-90.

Marshall J, Sugardjito J. 1986. Gibbon systematics. In: Swindler DR, Erwin J, editors. Comparative primate biology, volume 1: systematics, evolution, and anatomy. New York: Alan R. Liss, Inc. p137-85.

Mootnick AR. 2006. Gibbon (Hylobatidae) species identification recommended for rescue or breeding centers. Prim Conserv 21:103-38.

Palombit RA. 1996. The siamang and white-handed gibbon of Gunung Leuser National Park. In: van Schaik C, Supriatna J, editors. Leuser: a Sumatran sanctuary. Jakarta (ID): Yayasan Bina Sains Hayati Indonesia. p269-79.

Palombit RA. 1997. Inter- and intraspecific variation in the diets of sympatric siamang (Hylobates syndactylus) and la ribbons (Hylobates lar). Folia Primatol 68(6):321-37.

Raemaekers J. 1979. Ecology of sympatric gibbons. Folia Primatol 31:227-45.

Reichard U, Sommer V. 1997. Group encounters in wild gibbons (Hylobates lar): agonism, affiliation, and the concept of infanticide. Behaviour 134(15-16):1135-74.

Reichard UH. 2003. Social monogamy in gibbons: the male perspective. In: Reichard UH, Boesch C, editors. Monogamy: mating strategies and partnerships in birds, humans and other mammals. Cambridge(UK):Cambridge U Pr. p190-213.

Reichard UH, Barelli C. 2008. Life history and reproductive strategies of Khao Yai Hylobates lar: implications for social evolution in apes. Int J Primatol 29(4):823-44.

Roonwal ML, Mohnot SM. 1977. Primates of south Asia: ecology, sociobiology, and behavior. Cambridge (MA):Harvard U Pr. 421p.

Ungar PS. 1995. Fruit preferences of four sympatric primate species at Ketambe, northern Sumatra, Indonesia. Int J Primatol 16(2):221-45.

C Whitington and U Treesucon. Selection and treatment of food plants by white-handed gibbons (Hylobates lar) in Khao Yai national park, Thailand. NAT. HIST. BULL. SIAM SOC. 39: lll-122, 1991

Yimkao P, Srikosamatara S. 2006. Ecology and site-based conservation of the white-handed gibbon (Hylobates lar L.) in human-use forests in Mae Hong Son province, northern Thailand. Nat Hist Bull Siam Soc 54(1):109-38. 

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