Jump to content

Siamang: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
 
(389 intermediate revisions by more than 100 users not shown)
Line 1: Line 1:
{{Short description|Species of ape}}
{{Taxobox
{{Speciesbox
| name = Siamang<ref name=MSW3>{{MSW3 Groves|pages=181}}</ref>
| name = Siamang<ref name=MSW3>{{MSW3 Primates|id= 12100785|page=181}}</ref>
| status = EN
| status = EN
| status_system = iucn3.1
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Nijman, V. |author2=Geissmann, T. |author3=Traeholt, C. |author4=Roos, C. |author5=Nowak, M.G. |date=2020 |title=''Symphalangus syndactylus'' |volume=2020 |page=e.T39779A17967873 |doi=10.2305/IUCN.UK.2020-2.RLTS.T39779A17967873.en |access-date=19 November 2021}}</ref>
| trend = unknown
| status2 = CITES_A1
| status_ref = <ref name="iucn">{{IUCN2006|assessors=Eudey ''et al''|year=2000|id=39779|title=Symphalangus syndactylus|downloaded=11 May 2006}} </ref>
| status2_system = CITES
| image = Suneko - shout (by).jpg
| status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref>
| image_width = 250px
| image = Siamang Tierpark Hellabrunn-4.jpg
| regnum = [[Animal]]ia
| fossil_range = Middle [[Pleistocene]]-[[Holocene|Present]]<ref name=Suraprasit2016>{{cite journal|author=K. Suraprasit, J.-J. Jaegar, Y. Chaimanee, O. Chavasseau, C. Yamee, P. Tian, and S. Panha|title=The Middle Pleistocene vertebrate fauna from Khok Sung (Nakhon Ratchasima, Thailand): biochronological and paleobiogeographical implications|journal=ZooKeys|date=2016|issue=613 |pages=1–157|doi=10.3897/zookeys.613.8309|pmid=27667928 |pmc=5027644 |doi-access=free |bibcode=2016ZooK..613....1S }}</ref>
| phylum = [[Chordata]]
| classis = [[Mammal]]ia
| genus = Symphalangus
| ordo = [[Primate]]s
| parent_authority = [[Gloger]], 1841
| species = syndactylus
| familia = [[Hylobatidae]]
| authority = ([[Thomas Stamford Raffles|Raffles]], 1821)
| genus = '''''Symphalangus'''''
| range_map = Distribución symphalangus.png
| genus_authority = [[Gloger]], 1841
| range_map_caption = Distribution of the siamang
| species = '''''S. syndactylus'''''
| binomial = ''Symphalangus syndactylus''
| binomial_authority = ([[Thomas Stamford Raffles|Raffles]], 1821)
}}
}}
[[File:Siamang mid song.jpg|thumb]]
The '''siamang''' ({{IPAc-en|"|s|i:|@|m|{|N}}, {{small|also}} {{IPAc-en|UK|"|s|aI|@|-}};<ref>{{cite dictionary|dictionary=[[Lexico]]|title=siamang|url=https://www.lexico.com/definition/siamang|access-date=2022-04-26|archive-date=2022-04-26|archive-url=https://web.archive.org/web/20220426194648/https://www.lexico.com/definition/siamang|url-status=dead}}</ref><ref>{{Cite web|title=Definition of siamang {{!}} Dictionary.com|url=https://www.dictionary.com/browse/siamang|access-date=2022-02-14|website=www.dictionary.com|language=en}}</ref> '''''Symphalangus syndactylus''''') is an endangered [[arboreal]], black-furred [[gibbon]] native to the forests of [[Indonesia]], [[Malaysia]], and [[Thailand]]. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching {{cvt|1|m|ft|abbr=on}} in height, and weighing up to {{cvt|14|kg|lb|abbr=on}}. It is the only species in the genus '''''Symphalangus'''''. Fossils of siamangs date back to the [[Middle Pleistocene]].<ref name=Suraprasit2016/>


Two features distinguish the siamang from other gibbons. First, two digits on each foot—the second and third toes—are partially joined by a membrane, hence the [[species|specific]] name ''[[Syndactyly|syndactylus]]'', from the [[Ancient Greek]] σύν, ''sun-'', "with" + δάκτυλος, ''daktulos'', "finger". Second, a large [[gular sac]] (throat pouch), found in both males and females of the species, can be inflated to the size of the siamang's head, allowing it to make resonating calls.
The '''Siamang''' (''Symphalangus syndactylus'') is a tailless, [[arboreal]], black furred [[gibbon]] native to the forests of [[Malaysia]], [[Thailand]], and [[Sumatra]]. The largest of the [[lesser ape]]s, the Siamang can be twice the size of other gibbons, reaching 1 m in height, and weighing up to 23 kg. The Siamang is the only species in the genus '''''Symphalangus'''''.


Two [[subspecies]] of the siamang are the nominate [[Sumatra]]n siamang (''S. s. syndactylus'') and the Malaysian siamang (''S. s. continentis'', in [[Malay Peninsula]]).<ref name=Geissmann>{{cite web | last = Geissmann | first = Thomas | title = Gibbon Systematics and Species Identification | url = http://gibbons.de/main/system/intro.html | access-date = 2006-04-13}}</ref> Otherwise, the Malaysian individuals are only a population. The siamang occurs [[sympatrically]] with other gibbons; its two ranges are entirely within the combined ranges of the [[agile gibbon]] and the [[lar gibbon]].
The Siamang is distinctive for two reasons. The first is that two fingers on each hand are fused together (hence the name "[[syndactyl]]us"). The second is the large "gular sac" (found in both male and female of the species), which is a throat pouch that can be inflated to the size of its head, allowing the Siamang to make loud resonating calls or songs.


The siamang can live to around 40 years in captivity.<ref>Gron KJ. 2008 May 20. Primate Factsheets: Siamang (Symphalangus syndactylus) Taxonomy, Morphology, & Ecology . http://pin.primate.wisc.edu/factsheets/entry/siamang>. Accessed 2015 June 9.</ref>
There may be two subspecies of the Siamang. If so, they are the nominate Sumatran Siamang (''S. s. syndactylus'') and the Malaysian Siamang (''S. s. continentis'', in peninsular Malaysia).<ref name=Geissmann>{{cite web | last = Geissmann | first = Thomas | title = Gibbon Systematics and Species Identification | url = http://gibbons.de/main/system/intro.html | accessdate = 2006-04-13}}</ref> Otherwise, the Malaysian individuals are only a population. The Siamang is the only gibbon which occurs sympatrically with other gibbons; its two ranges are entirely within the combined ranges of the [[Agile Gibbon]] and the [[Lar Gibbon]].


While the illegal pet trade takes a toll on wild populations, the principal threat to the siamang is [[habitat loss]] in both [[Indonesia]] and [[Malaysia]]. The [[palm oil]] production industry is clearing large swaths of forest, reducing the habitat of the siamang, along with those of other species, such as the [[Sumatran tiger]].
The Siamang can live up to 30+ years in captivity.


== Description ==
While the illegal pet trade takes a toll on wild populations, the principal threat to the Siamang is habitat loss in both Malaysia and Sumatra. [[Palm oil]] production is clearing large swathes of forest, reducing the habitat of the Siamang, along with that of other species such as the [[Sumatran Tiger]].
[[File:Siamang Unkie SDZ CALVIN.jpg|thumb|A close-up of adult male's head]]
The siamang has long, dense, shaggy hair, which is the darkest shade of all gibbons. The ape's long, gangling arms are longer than its legs. The average length of a siamang is 90&nbsp;cm; the largest they have ever grown is 150&nbsp;cm. The face of this large gibbon is mostly hairless, apart from a thin mustache.


== Distribution and habitat ==
==Ecology==
The Siamang inhabits the forest remnants of Sumatra Island and the Malay Peninsula, and is widely distributed from lowland forest to montane forest. The Siamang lives in groups of up to 6 individuals (4 individuals on average) with a home range 23 hectares on average.<ref name=OBrien1/><ref name=OBrien>{{cite journal | author = O'Brien, T.G., M.F. Kinnaird, A. Nurcahyo, M. Prasetyaningrum, dan M. Iqbal | year = 2003 | title = Fire, demography and persistence of siamangs (Symphalangus syndactylus: Hylobatidae) in a Sumatran rainforest | journal = Animal Conservation | volume = 6 | pages = 115 | doi = 10.1017/S1367943003003159}}</ref> The Siamang's melodious choir singing breaks the forest's silence in the early morning after the Agile Gibbon or Lar Gibbon's calls. The Siamang in Sumatra and the Malay Peninsula are similar in appearance, but there are some differences in behaviour between the two populations.
The siamang inhabits the forest remnants of [[Sumatra]] Island and the [[Malay Peninsula]], and is widely distributed from lowland forest to mountain forest—even rainforest—and can be found at altitudes up to 3800 m.<ref name="Rowe, Noel 1996">Rowe, Noel. (1996) "Pictorial Guide to the Living Primates" Charlestown, RI: Pagonia Press</ref> It lives in groups of up to six individuals (four individuals on average) with an average home range of 23 hectares.<ref name=OBrien1/><ref name=OBrien>{{cite journal | author = O'Brien, T. G. | author2 = M. F. Kinnaird | author3 = A. Nurcahyo | author4 = M. Prasetyaningrum| author5 = Dan M. Iqbal | year = 2003 | title = Fire, demography and persistence of siamangs (Symphalangus syndactylus: Hylobatidae) in a Sumatran rainforest | journal = Animal Conservation | volume = 6 | issue = 2 | pages = 115 | doi = 10.1017/S1367943003003159| s2cid = 86035086 }}</ref> Their day ranges are substantially smaller than those of sympatric ''[[Hylobates]]'' species, often less than 1&nbsp;km.<ref name="Rowe, Noel 1996"/> The siamang's melodious singing breaks the forest's silence in the early morning after the agile gibbons' or lar gibbons' calls. The siamangs in [[Sumatra]] and the [[Malay Peninsula]] are similar in appearance, but some behaviors differ between the two populations.


== Ecology and behavior ==
===Diet===
Siamangs have an ecology and relationship between two types of gibbons that share the same habitat. Those include the Agile gibbon and Lar gibbon. Both of the gibbons that live with the siamangs are Hylobates rather than Symphalangus. When two siamangs meet, they often have a bond with each other. They might also communicate by using their throat pouches and shouts to communicate when they feel excited, relaxed, trying to mate, or threatened. If siamangs use loud sounds, they also use body language to communicate. They use sign language or pointing to make others aware of what they need or what they want to do.
The Siamang mainly eats various parts of plants. The Sumatran Siamang is more [[frugivorous]] than its Malayan cousin, with fruit making up to 60% of its diet. The Siamang eats at least 160 species of plants, from vines to woody plants. Its major food is [[fig]]s (''[[Ficus]]'' spp.), a member of [[Moraceae]] family.<ref name=OBrien/><ref name=Nurcahyo>Nurcahyo, A. (2001). Daily Ranging, Home-Range, Foods, Feeding and Calling in Siamang (Hylobates syndactylus). In WCS-IP 2001. Bukit Barisan Selatan National Park in Space and Time. 2000 -2001 Research Report. WCS-IP/ PHKA, Bogor. 35-52. (In Indonesian)</ref> The Siamang prefers to eat ripe fruit rather than unripe fruit, and young leaves rather than old leaves. It eats flowers and a few animals, mostly insects. When the Siamang eats large flowers, it will eat only the [[petal#corolla|corolla]] (petal), but it will eat all parts of smaller flowers, with the small fruit collected in its hand before being consumed. When it eats big and hard seeds or seeds with sharp edge it will peel out the fruit flesh and throw away the seed.<ref name=Nurcahyo/>
=== Diet ===
The siamang eats mainly various parts of plants. The Sumatran siamang is more [[frugivorous]] than its Malayan relative, with fruit making up to 60% of its diet. The siamang eats at least 160 species of plants, from [[vine]]s to woody plants. Its major food source is figs (''[[Ficus]]'' spp.).<ref name=OBrien/><ref name=Nurcahyo>Nurcahyo, A. (2001). Daily Ranging, Home-Range, Foods, Feeding and Calling in Siamang (Hylobates syndactylus). In WCS-IP 2001. Bukit Barisan Selatan National Park in Space and Time. 2000 -2001 Research Report. WCS-IP/ PHKA, Bogor. 35–52. (In Indonesian)</ref> The siamang prefers to eat ripe rather than unripe fruit, and young rather than old leaves. It eats flowers and a few animals, mostly insects. When the siamang eats large flowers, it eats only the [[petal#Corolla|corolla]]e (petals), but it eats all parts of smaller flowers, with the small fruit collected in its hand before being consumed. When it eats big and hard seeds or seeds with sharp edges, it peels out the fruit flesh and throws away the seed.<ref name=Nurcahyo/> Although its diet consists of substantial portions of fruit, it is the most [[folivorous]] of all members of [[gibbon|Hylobatidae]].<ref name="Rowe, Noel 1996"/> As it is also the largest gibbon, it fits well with the general primate dietary trend in which larger primates tend to be more folivorous.<ref>Fleagle J. G. (1988). Size and Adaptation in Primates. In Jungers WL (ed). "Size and Scaling in Primate Biology". New York: Plenum Press.</ref>


===Demography and population===
=== Demography and population ===
A group of Siamang normally consist of an adult dominant male, an adult dominant female, with offspring, infant and sometimes a sub-adult. The sub-adult usually leaves the group after the age 6 to 8 years; sub-adult females tend to leave the group earlier than sub-adult males. A study in relation to effect of habitat disturbance on the Siamang found that group composition is varied in age-sex structure between intact forest and post-burnt forest. The post-burnt population was more adult and sub-adults than the intact population. Post-burnt groups contain fewer infants, small juveniles and large juveniles compared to intact forest groups. Infant survival rates in post-burnt groups are lower than in intact forests. The number of individuals in intact forests is higher than in post-burnt forests.<ref name=OBrien/> The Siamang in disturbed forests live in small groups and have a density lower than in intact forests because of lack of food resources and trees for living.
A group of siamangs normally consists of an adult dominant male, an adult dominant female, with offspring, infants, and sometimes a subadult. The subadult usually leaves the group after attaining the age of 6–8 years; subadult females tend to leave the group earlier than subadult males. Siamang gestation period is between 6.2 and 7.9 months; after the infant is born, the mother takes care of the infant for the first year of its life.<ref name="Lappan, Susan">Lappan, Susan. (2008). "Male Care of Infants in a Siamang (''Symphalangus syndactylus'') Population including Socially Monogamous and Polyandrous Groups". Behavioral Ecology and Sociobiology. 62(8): 1307–1317.</ref> Siamang males tend to offer more paternal care than do other members of the family Hylobatidae, taking up a major role in carrying an infant after it is about 8 months old.<ref name="Rowe, Noel 1996"/> The infant typically returns to its mother to sleep and nurse. The infant begins to travel independently from its parents by its third year of life.<ref name = "Chivers"/>
[[Image:Siamang inflated throat pouch.jpg|thumb|left|240px]]
In the 1980s, the Indonesian population of the Siamang in the wild was estimated to be 360,000 individuals.<ref name=Nijman/> This seems over-estimate today, as an example, Bukit Barisan Selatan National Park (BBSNP) is the third largest protected area (3,568 km²) in Sumatra, of which approximately 2,570 km² remains under forest cover inhabit by 22,390 siamangs (in 2002 censuses). According to two different research projects conducted in Sumatra, the Siamang prefer to inhabit lowland forest below between 500 m in altitude and over 1000 m above sea level.<ref name=OBrien1/>


Siamangs are generally known to have monogamous mating pairs, which have been documented to spend more time in close proximity to each other, in comparison to other gibbon species.<ref>Palombit, Ryne A. (1996). “Pair Bonds in Monogamous Apes: A Comparison of the Siamang, Hylobates syndactylus, and the White-Handed Gibbon Hylobates lar. Behaviour. 133 (5) 321-356.</ref> Both monogamous and polyandrous groups, though, are found in [[South Sumatra]].<ref name ="Lappan, Susan"/> In studying these populations, infants belonging to monogamous groups were found to receive more overall male care than infants in the polyandrous groups. This reduced care is most likely due to reduced certainty of paternity in these groups.<ref name ="Lappan, Susan"/>
===Behaviour===
The Siamang tends to rest for more than 50% of its waking period (from dawn to dusk), followed by feeding, moving, foraging and social activities. It takes more rest during midday, taking time to groom each other or play. During resting time it usually uses a branch of a large tree lying on their back or on their stomach. Feeding behaviors, foraging, and moving are most often in the morning and after resting time.
[[Image:DPPP 5348.jpg|thumb|left|240px]]DPPP 5348.jpg
In the dry season the length of the Siamang's daily range is longer than in the rainy season. The Siamang in southern Sumatra undertakes less foraging than the Siamang in other places because it eats more fruit and therefore consumes more nutrition, which results in less time needed for looking for food. Sometimes the Siamang will spend all of the day in one big fruiting tree, just moving out when it wants to rest and then coming back again to fruiting trees.<ref name=Nurcahyo/>


Habitat disturbance affects siamang group composition; it is varied in age-sex structure between intact forest and burnt, regrown forest. The burnt, regrown forest population contained more adult and subadults than the intact forest population, which had more infants, small juveniles, and large juveniles. Infant survival rates in burnt, regrown forest groups are lower than in intact forest groups. The number of individuals in the latter is higher than in the former.<ref name=OBrien/> The siamang in disturbed forests live in small groups and have a density lower than in intact forests because of lack of food resources and trees for living.
===Role of calling===
The Siamang starts its day by calling in the early morning and calls less after midday, with the peak of their calls around 9:00 am to 10:00 am. Most of the Siamang's calls are directed to its neighbours rather than to inside its home range. This means that the Siamang's calling is in response to disturbances and is to defend its territory. Calls in the late morning typically happen when it meets or sees another Siamang group. The edge of the Siamang's home range, which may overlap another, is often the places where calling is made. Counter-call (co-response calling) occasionally happens near the border or in the overlap area. Calls are numerous when fruit is more abundant rather than when fruit is less available. Branch shaking, swinging, and moving around the tree crowns accompany the calling. This movement might be to show the other groups where they are.


In the 1980s, the [[Indonesia]]n population of the siamang in the wild was estimated to be 360,000 individuals.<ref name=Nijman/> This figure may be less in the 21st century: [[Bukit Barisan Selatan National Park]] is the third-largest protected area ({{convert|3568|km2|disp=or|abbr=on}}) in [[Sumatra]], of which roughly {{convert|2570|km2|abbr=on}} remain under forest cover inhabited by 22,390 siamangs (in 2002 censuses). In [[Sumatra]], the siamang prefers to inhabit lowland forest between {{convert|500|and|1000|m|abbr=on}} above sea level.<ref name=OBrien1/>
The Siamang prefers calling in the living, high and big trees, it might be the places where another group is easy to see. Beside that, living, big, and tall trees can support Siamang movement. Calling trees are usually near feeding trees but sometimes they call in the feeding trees.<ref name=Nurcahyo/><ref name=Kinnaird1>{{cite journal | author = Kinnaird, M.F., O’Brien, T.G., Nurcahyo, A. and Prasetyaningrum, M. | year = 2002 | title = Intergroup spacing and the role of calling among siamangs | journal = Proceedings of the XIX Congrees of the International Primatological Society (abstract)}}</ref>


===Siamang and their habitat===
=== Behavior ===
The siamang tends to rest for more than half of its waking period from dawn to dusk, followed by feeding, moving, foraging, and social activities. It takes more rest during midday, taking time to groom others or to play. During resting time, it usually uses a branch of a large tree, lying on its back or belly. Feeding behaviors, foraging, and moving are most often in the morning and after resting. Grooming is one of the most important social interactions among family members. Grooming takes place between adults earlier in the day; the adults groom the juveniles later in the day. Adult males are the most involved in grooming.<ref name = Chivers/>
As a frugivorous animal, the Siamang disperses seeds through defacation as it travels across its territory. The Siamang can carry seed and defecate over 300 m with the shortest distance being 47.6 m from the seed resource, which supports the forest regeneration and succession.<ref name=Rusmanto>Rusmanto, M. (2001). Seed dispersal by siamang (Hylobates syndactylus). In WCS-IP 2001. Bukit Barisan Selatan National Park in Space and Time. 2000 -2001 Research Report. WCS-IP/ PHKA, Bogor. 53-64. (In Indonesian)</ref>

[[Image:DPPP 5348.jpg|thumb|240px| A siamang group at rest in [[Sumatra]], [[Indonesia]] - siamangs rest up to 50% of their waking hours.]]
In the dry season, the size of the siamang's daily range is larger than in the rainy season. The siamang in [[South Sumatra|southern Sumatra]] spends less time foraging than siamangs in other places, as it eats a diet higher in fruit. It thus consumes more nutrients, which results in less time needed for food acquisition. A siamang may spend an entire day in a single fruiting tree, moving out when it wants to rest and returning to feed.<ref name=Nurcahyo/>

Siamangs are a very social species of primates and exhibit a variety of tactile and visual gestures, along with actions and facial expressions to communicate and increase social bonds within their family group.<ref>Liebal, Pika, and Tomasello. (2004). “Social Communication in Siamangs (Symphalangus syndactylus): use of gestures and facial expressions” Primates. 45(1): 41-57.</ref> They are also territorial, and interact with other family groups by making loud calls to let other groups know where their territory is. The calls may be asynchronous, where they are not directed at a particular neighbouring group, or simultaneous group calls may take place across the territory boundary. Males are known to chase one another across the boundary.<ref name = Chivers/>

{{anchor|Copulation}}
Grooming frequency between males and females has been found to correlate to copulation frequency, as well as bouts of aggression. Pairs copulate over four to five months at intervals of two to three years. The peak of their reproductive activity is often during the time when fruit is most abundant.<ref name = Chivers/> Dorsoventral copulation is the most common type in siamangs, where the female is squatting and the male hangs by his arms and grips the female with his legs, whereas ventroventral copulation, where both primates are suspended, occurs only one in 60 times on average.<ref name = Chivers>[https://www.jstor.org/discover/10.2307/4533736?uid=3739912&uid=2&uid=4&uid=3739256&sid=47698812092497 Chivers, David J. (1976). Communication within and between family groups of siamang (''Symphalangus syndactylus''). Behaviour 57 (1-2): 116-135.]</ref>

=== Role of calling ===
[[File:Symphalangus syndactylus 4zz.jpg|thumb|Siamang calling with throat sac inflated]]
[[File:Symphalangus syndactylus 20170623 Doué-la-Fontaine.ogg|thumb|Siamangs' call]]
[[File:Black-gibbons-sumatra-2022.ogg|thumb|Siamang, Sumatra, 2022]]

The siamang starts its day by calling in the early morning; it calls less after midday, with the peak of the calls around 9:00 to 10:00 am. Most of the siamang's calls are directed to its neighbours rather than to those inside its home range. This means the siamang's calling is in response to disturbances and to defend its territory. Calls in the late morning typically happen when it meets or sees another siamang group. The edge of the siamang's home range, which may overlap another, is often the place where calling is made. Counter (co-response) calling occasionally happens near the border or in the overlap area. Calls are numerous when fruit is more abundant rather than when it is less available. Branch shaking, swinging, and moving around the tree crowns accompany the calling. This movement might be to show the other groups where they are.

The siamang prefers calling in the living, tall, and big trees, possibly where another group is easy to see. Besides that, such trees can support siamang movement. Calling trees are usually near feeding trees, but sometimes they call in the feeding trees.<ref name=Nurcahyo/><ref name=Kinnaird1>{{cite journal | author = Kinnaird, M. F. | author2 = O’Brien, T. G. | author3 = Nurcahyo, A. | author4 = Prasetyaningrum, M. | name-list-style = amp | year = 2002 | title = Intergroup spacing and the role of calling among siamangs | journal = Proceedings of the XIX Congress of the International Primatological Society (Abstract)}}</ref>

Mated pairs produce loud, well-patterned calling bouts, which are referred to as duetting. These calls advertise the presence and status of a mated pair.<ref name = Geissmann/> Newly formed pairs spend more time singing than an established pair. Advertising the presence of a strong bond is advantageous in territorial defense.<ref>{{cite journal|last=Geissmann|first=Thomas|title=Mate Change Enhances Duetting Activity in the Siamang Gibbon (Hylobates syndactylus)|journal=Behaviour|year=1986|volume=1|issue=96|pages=17–27|doi=10.1163/156853986x00199}}</ref> Siamang duetting differs from other species because it has a particularly complex vocal structure. Four distinct classes of vocalizations have been documented: booms, barks, ululating screams, and bitonal screams. Females typically produce long barks and males generally produce bitonal screams, but both sexes have been known to produce all four classes of vocalizations.<ref>{{cite journal|last=Geissmann|first=Thomas|title=Duet Songs of the Siamang, Hylobates Syndactylus: II. Testing the Pair-Bonding Hypothesis during a Partner Exchange|journal=Behaviour|year=1999|volume=8|issue=136|pages=1005–1039|doi=10.1163/156853999501694|s2cid=54736136}}</ref> Unlike other gibbons in which vocalization is added by laterally expanded [[Laryngeal saccules|laryngeal sacs]], those in siamangs fuse with each other and extend into the ventral area of the neck.<ref name="Koda Nishimura Tokuda Oyakawa 2012 pp. 347–355">{{cite journal |last1=Koda |first1=Hiroki |last2=Nishimura |first2=Takeshi |last3=Tokuda |first3=Isao T. |last4=Oyakawa |first4=Chisako |last5=Nihonmatsu |first5=Toshikuni |last6=Masataka |first6=Nobuo |date=2012 |title=Soprano singing in gibbons |journal=American Journal of Physical Anthropology |volume=149 |issue=3 |pages=347–355 |doi=10.1002/ajpa.22124 |pmid=22926979 |issn=0002-9483}}</ref>

=== Seeding ===
As a frugivorous animal, the siamang disperses seeds through defecation as it travels across its territory. The siamang can carry seed while digesting, and defecate between {{cvt|81.9|and|365.9|m}} from the seed resource, which supports the forest's regeneration and [[Ecological succession|succession]].<ref name=Rusmanto>{{cite journal |last1=Adyn |first1=M.F. |last2=Sibarani |first2=M.C. |last3=Utoyo |first3=L. |last4=Surya |first4=R.A. |last5=Sedayu |first5=A. |title=Role of siamang (Symphalangus syndactylus) as seed dispersal agent in a Sumatran lowland tropical forest |journal=Biodiversitas | issn=1412-033X |volume=23 |issue=4 |date=April 2022 |pages=2101–2110 |doi=10.13057/biodiv/d230445|s2cid=248447919 |doi-access=free }}</ref>

==Threats and conservation==
As an arboreal primate whose survival absolutely depends on the forest, the siamang faces [[population pressure]] due to habitat loss,<ref name=OBrien1>{{cite journal | author = O'Brien, T.G. | author2 = M.F. Kinnaird | author3 = A. Nurcahyo | author4 = M. Iqbal | author5 = M. Rusmanto | name-list-style = amp | year = 2004 | title = Abundance and Distribution of Sympatric Gibbons in a Threatened Sumatran Rainforest | journal = International Journal of Primatology | volume = 25 | issue = 2 | pages = 267–284 | doi = 10.1023/B:IJOP.0000019152.83883.1c| s2cid = 32472118 }}</ref> [[poaching]], and hunting.<ref name=Nijman>Nijman, V. (2005). In Full Swing: An Assessment of Trade in Orang-Utans and Gibbons on Java and Bali, Indonesia. A Traffict Southeast Asia Report. Traffic Southeast Asia</ref><ref name=Nursahid>Nursahid, R. and Bakdiantoro, H. (2005). Illegal Primate Trade in Indonesia. Profauna Indonesia. Presentation in SEAPA 1st Congress.</ref>


==Threats to population==
The Siamang, as an arboreal primate, absolutely depends on the forest for existence, needing trees for its living. At the moment, the Siamang is facing a population decrease due to habitat loss<ref name=OBrien1>{{cite journal | author = O'Brien, T.G., M.F. Kinnaird, A. Nurcahyo, M. Iqbal and M. Rusmanto | year = 2004 | title = Abundance and Distribution of Sympatric Gibbons in a Threatened Sumatran Rainforest | journal = International Journal of Primatology | volume = 25 | pages = 267–284 | doi = 10.1023/B:IJOP.0000019152.83883.1c}}</ref>, poaching and hunting.<ref name=Nursahid>Nursahid, R. and Bakdiantoro, H. (2005). Illegal Primate Trade in Indonesia. Profauna Indonesia. Presentation in SEAPA 1st Congress.</ref><ref name=Nijman>Nijman,V. (2005). In Full Swing: An Assessment of Trade in Orang-Utans and Gibbons on Java and Bali, Indonesia. A Traffict Southeast Asia Report. Traffic Southeast Asia</ref>
[[Image:Siamang Hellabrunn 2004.jpg|thumb|left|240px]]
===Habitat loss===
===Habitat loss===
[[Image:Siamang Hellabrunn 2004.jpg|thumb|240px|Siamang, [[Tierpark Hellabrunn]], Munich, Germany]]
A major threat to the Siamang is habitat loss due to plantation, forest fire, illegal logging, encroachment, and human development. Firstly, palm oil plantations have removed large areas of the Siamang's habitat in the last four decades. Since 2002 107,000 square kilometres of palm oil have been planted,<ref name=Palmer>Palmer, C. E. The Extent and Causes of Illegal Logging: An Analysis of a Major Cause of Tropical Deforestation in Indonesia. CSERGE Working Paper.</ref> which has replaced much rainforest in Indonesia and Malaysia, where the Siamang originally used to live. Secondly, in the last two decades, forest fire destroyed more than 20,000 km² of Sumatran rainforest, mainly in the lowland area where most of the Siamang live. Thirdly, the rate of illegal logging in Indonesia increased from 1980 to 1995 and even more rapidly after the reformation era beginning in 1998.<ref name=Palmer/> These illegal activities devastated the remaining tropical rainforest especially in Sumatra. Fourthly, forest encroachments change forest cover into cultivated land, for example; the rising price of coffee in 1998 has been encouraging people in Sumatra to replace the forest with coffee plantation.<ref name=Kinnaird>{{cite journal | author = Kinnaird, M.F., Sanderson, E.W., O'Brien, T.G., Wibisono, H.T., and Woolmer, G. | year = 2003 | title = Deforestation trends in a tropical landscape and implications for endangered mammals | journal = Cons. Biol. | volume = 17 | pages = 245–257 | doi = 10.1046/j.1523-1739.2003.02040.x}}</ref> Fifthly, development in many areas needs infrastructure such as roads, which now divide a lot of conservation areas have been caused forest fragmentation and edge effects. Unfortunately, the Siamang as an arboreal primate faces difficulty because road establishment has disconnected their pathways.


A major threat to the siamang is [[habitat fragmentation]] due to [[plantation]]s, [[forest fire]], [[illegal logging]], [[wikt:encroachment|encroachment]], and human development. Firstly, palm-oil plantations have removed large areas of the siamang's habitat in recent decades. Since 2002, 107,000&nbsp;km<sup>2</sup> of [[oil palm]] have been planted,<ref name=Palmer>Palmer, C. E. The Extent and Causes of Illegal Logging: An Analysis of a Major Cause of Tropical Deforestation in Indonesia. CSERGE Working Paper.</ref> which has replaced much rainforest in [[Indonesia]] and [[Malaysia]], where the siamang originally lived. Secondly, in the second decade of the 21st century, forests in the [[Malay Peninsula]] have been destroyed due to illegal logging. Sixteen out of the 37 permanent forest reserves in [[Kelantan]], in the Malay Peninsula, where most of the siamangs live, have been encroached upon by illegal loggers.<ref>{{cite web |url=https://www.malaymail.com/amp/news/malaysia/2020/12/07/illegal-logging-detected-in-16-kelantan-forest-reserves/1929666 |title= Illegal logging detected in 16 Kelantan forest reserves|author=<!--Not stated--> |date=7 December 2020 |website= malaymail.com|publisher=Malay Mail |access-date= 17 January 2021|quote=}}</ref> Thirdly, forest encroachments change forest cover into cultivated land; for example, the rising price of coffee in 1998 encouraged people in [[Sumatra]] to replace the forest with coffee plantations.<ref name=Kinnaird>{{cite journal | author = Kinnaird, M.F. | author2 = Sanderson, E.W. | author3 = O'Brien, T.G. | author4 = Wibisono, H.T. | author5 = Woolmer, G. | name-list-style = amp | year = 2003 | title = Deforestation trends in a tropical landscape and implications for endangered mammals | journal = Conservation Biology | volume = 17 | pages = 245–257 | doi = 10.1046/j.1523-1739.2003.02040.x| s2cid = 59583614 }}</ref> Fourthly, development in many areas requires infrastructure, such as roads, which now divide conservation areas and have caused forest fragmentation and [[edge effect]]s.
===Poaching and hunting===

Unlike other parts of Asia, primates are not hunted for their meat in Indonesia (the exception is in Chinese restaurants in Indonesia which sometimes serve macaque on their menu). However, they are poached and hunted for the illegal pet trade, mostly for infant Siamang. Poachers kill the mothers because mother Siamang are highly protective of their infants. It is therefore very difficult to remove the infant without first killing the mother. Despite the fact that most Siamang on the market are infants many infants nevertheless die during transportation.<ref name=Nursahid/><ref name=Nijman/
=== Poaching and hunting ===
Unlike other parts of Asia, primates are not hunted for their meat in Indonesia. They are hunted for the [[Wildlife smuggling|illegal pet trade]], with hunters preferring infant siamangs. Poachers often kill the mothers first, since siamang females are highly protective of their infants, and removing the infant without first killing the mother requires more effort. Most siamangs on the market are infants, which often die during transportation.<ref name=Nijman/><ref name=Nursahid/>

===Conservation===
Siamang can be found in at least 11 protected areas:
;Indonesia
* [[Bukit Barisan Selatan National Park]]
* [[Gunung Leuser National Park]]
* [[Kerinci Seblat National Park]]
* [[Langkat Barat Wildlife Reserve]]
* [[Way Kambas National Park]]
;Malaysia
* [[Fraser's Hill Reserve]]
* [[Gunong Besout Forest Reserve]]
* [[Krau Wildlife Reserve]]
* [[Ulu Gombak Wildlife Reserve]]
;Thailand
* [[Hala Bala Wildlife Sanctuary]]<ref name="iucn status 19 November 2021" />


==References==
==References==
{{reflist}}
{{Reflist|2}}


==External links==
==External links==
{{commons|Symphalangus syndactylus|Siamang}}
{{Commons|Symphalangus syndactylus|Siamang}}
{{Wikispecies|Symphalangus}}
{{Wikispecies|Symphalangus}}
{{Wikispecies|Symphalangus syndactylus|Siamang}}
{{Wikispecies|Symphalangus syndactylus|Siamang}}
*[http://www.gibbons.de/main/photo/12synd.html Siamang photos]
*[http://www.gibbons.de/main/index.html Siamang photos]
*[http://www.gibbons.de/main/sound/12synd.html Siamang songs]
*[http://www.gibbons.de/main/sound/12synd.html Siamang songs]
*[http://www.gibboncenter.org/ Gibbon Conservation Center]
*[http://www.gibboncenter.org/ Gibbon Conservation Center]
* [http://pin.primate.wisc.edu/factsheets/entry/siamang Primate Info Net ''Symphalangus syndactylus'' Factsheet]
*[http://pin.primate.wisc.edu/factsheets/entry/siamang Primate Info Net ''Symphalangus syndactylus'' Factsheet]
*http://www.sandiegozoo.org/animalbytes/t-siamang.html


{{Hylobatidae nav}}
{{Hylobatidae nav}}
{{Haplorhini|Ho.}}
{{Taxonbar|from1=Q1962797|from2=Q213889|from3=Q41167995|from4=Q46679442}}
{{Authority control}}


[[Category:Apes]]
[[Category:Gibbons]]
[[Category:Mammals of Southeast Asia]]
[[Category:Fauna of Sumatra]]
[[Category:Fauna of Thailand]]
[[Category:Fauna of Southeast Asia]]
[[Category:Mammals of Indonesia]]
[[category:Sumatra]]
[[Category:Mammals of Malaysia]]

[[Category:Mammals of Thailand]]
[[da:Siamang]]
[[Category:Primates of Southeast Asia]]
[[de:Siamang]]
[[Category:Primates of Indonesia]]
[[es:Symphalangus syndactylus]]
[[Category:Species that are or were threatened by the pet trade]]
[[fr:Siamang]]
[[Category:Mammals described in 1821]]
[[it:Symphalangus syndactylus]]
[[Category:Taxa named by Thomas Stamford Raffles]]
[[he:סיאמנג]]
[[ka:სიამანგი]]
[[lt:Siamangas]]
[[hu:Sziamang]]
[[ms:Siamang]]
[[nl:Siamang]]
[[ja:フクロテナガザル]]
[[pl:Siamang]]
[[ru:Сиаманг]]
[[simple:Siamang]]
[[th:ชะนีดำใหญ่]]
[[zh-yue:合趾猿]]
[[zh:合趾猿]]

Latest revision as of 02:27, 14 December 2024

Siamang[1]
Temporal range: Middle Pleistocene-Present[2]
CITES Appendix I (CITES)[4]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Hylobatidae
Genus: Symphalangus
Gloger, 1841
Species:
S. syndactylus
Binomial name
Symphalangus syndactylus
(Raffles, 1821)
Distribution of the siamang

The siamang (/ˈsiːəmæŋ/, also UK: /ˈsaɪə-/;[5][6] Symphalangus syndactylus) is an endangered arboreal, black-furred gibbon native to the forests of Indonesia, Malaysia, and Thailand. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching 1 m (3.3 ft) in height, and weighing up to 14 kg (31 lb). It is the only species in the genus Symphalangus. Fossils of siamangs date back to the Middle Pleistocene.[2]

Two features distinguish the siamang from other gibbons. First, two digits on each foot—the second and third toes—are partially joined by a membrane, hence the specific name syndactylus, from the Ancient Greek σύν, sun-, "with" + δάκτυλος, daktulos, "finger". Second, a large gular sac (throat pouch), found in both males and females of the species, can be inflated to the size of the siamang's head, allowing it to make resonating calls.

Two subspecies of the siamang are the nominate Sumatran siamang (S. s. syndactylus) and the Malaysian siamang (S. s. continentis, in Malay Peninsula).[7] Otherwise, the Malaysian individuals are only a population. The siamang occurs sympatrically with other gibbons; its two ranges are entirely within the combined ranges of the agile gibbon and the lar gibbon.

The siamang can live to around 40 years in captivity.[8]

While the illegal pet trade takes a toll on wild populations, the principal threat to the siamang is habitat loss in both Indonesia and Malaysia. The palm oil production industry is clearing large swaths of forest, reducing the habitat of the siamang, along with those of other species, such as the Sumatran tiger.

Description

[edit]
A close-up of adult male's head

The siamang has long, dense, shaggy hair, which is the darkest shade of all gibbons. The ape's long, gangling arms are longer than its legs. The average length of a siamang is 90 cm; the largest they have ever grown is 150 cm. The face of this large gibbon is mostly hairless, apart from a thin mustache.

Distribution and habitat

[edit]

The siamang inhabits the forest remnants of Sumatra Island and the Malay Peninsula, and is widely distributed from lowland forest to mountain forest—even rainforest—and can be found at altitudes up to 3800 m.[9] It lives in groups of up to six individuals (four individuals on average) with an average home range of 23 hectares.[10][11] Their day ranges are substantially smaller than those of sympatric Hylobates species, often less than 1 km.[9] The siamang's melodious singing breaks the forest's silence in the early morning after the agile gibbons' or lar gibbons' calls. The siamangs in Sumatra and the Malay Peninsula are similar in appearance, but some behaviors differ between the two populations.

Ecology and behavior

[edit]

Siamangs have an ecology and relationship between two types of gibbons that share the same habitat. Those include the Agile gibbon and Lar gibbon. Both of the gibbons that live with the siamangs are Hylobates rather than Symphalangus. When two siamangs meet, they often have a bond with each other. They might also communicate by using their throat pouches and shouts to communicate when they feel excited, relaxed, trying to mate, or threatened. If siamangs use loud sounds, they also use body language to communicate. They use sign language or pointing to make others aware of what they need or what they want to do.

Diet

[edit]

The siamang eats mainly various parts of plants. The Sumatran siamang is more frugivorous than its Malayan relative, with fruit making up to 60% of its diet. The siamang eats at least 160 species of plants, from vines to woody plants. Its major food source is figs (Ficus spp.).[11][12] The siamang prefers to eat ripe rather than unripe fruit, and young rather than old leaves. It eats flowers and a few animals, mostly insects. When the siamang eats large flowers, it eats only the corollae (petals), but it eats all parts of smaller flowers, with the small fruit collected in its hand before being consumed. When it eats big and hard seeds or seeds with sharp edges, it peels out the fruit flesh and throws away the seed.[12] Although its diet consists of substantial portions of fruit, it is the most folivorous of all members of Hylobatidae.[9] As it is also the largest gibbon, it fits well with the general primate dietary trend in which larger primates tend to be more folivorous.[13]

Demography and population

[edit]

A group of siamangs normally consists of an adult dominant male, an adult dominant female, with offspring, infants, and sometimes a subadult. The subadult usually leaves the group after attaining the age of 6–8 years; subadult females tend to leave the group earlier than subadult males. Siamang gestation period is between 6.2 and 7.9 months; after the infant is born, the mother takes care of the infant for the first year of its life.[14] Siamang males tend to offer more paternal care than do other members of the family Hylobatidae, taking up a major role in carrying an infant after it is about 8 months old.[9] The infant typically returns to its mother to sleep and nurse. The infant begins to travel independently from its parents by its third year of life.[15]

Siamangs are generally known to have monogamous mating pairs, which have been documented to spend more time in close proximity to each other, in comparison to other gibbon species.[16] Both monogamous and polyandrous groups, though, are found in South Sumatra.[14] In studying these populations, infants belonging to monogamous groups were found to receive more overall male care than infants in the polyandrous groups. This reduced care is most likely due to reduced certainty of paternity in these groups.[14]

Habitat disturbance affects siamang group composition; it is varied in age-sex structure between intact forest and burnt, regrown forest. The burnt, regrown forest population contained more adult and subadults than the intact forest population, which had more infants, small juveniles, and large juveniles. Infant survival rates in burnt, regrown forest groups are lower than in intact forest groups. The number of individuals in the latter is higher than in the former.[11] The siamang in disturbed forests live in small groups and have a density lower than in intact forests because of lack of food resources and trees for living.

In the 1980s, the Indonesian population of the siamang in the wild was estimated to be 360,000 individuals.[17] This figure may be less in the 21st century: Bukit Barisan Selatan National Park is the third-largest protected area (3,568 km2 or 1,378 sq mi) in Sumatra, of which roughly 2,570 km2 (990 sq mi) remain under forest cover inhabited by 22,390 siamangs (in 2002 censuses). In Sumatra, the siamang prefers to inhabit lowland forest between 500 and 1,000 m (1,600 and 3,300 ft) above sea level.[10]

Behavior

[edit]

The siamang tends to rest for more than half of its waking period from dawn to dusk, followed by feeding, moving, foraging, and social activities. It takes more rest during midday, taking time to groom others or to play. During resting time, it usually uses a branch of a large tree, lying on its back or belly. Feeding behaviors, foraging, and moving are most often in the morning and after resting. Grooming is one of the most important social interactions among family members. Grooming takes place between adults earlier in the day; the adults groom the juveniles later in the day. Adult males are the most involved in grooming.[15]

A siamang group at rest in Sumatra, Indonesia - siamangs rest up to 50% of their waking hours.

In the dry season, the size of the siamang's daily range is larger than in the rainy season. The siamang in southern Sumatra spends less time foraging than siamangs in other places, as it eats a diet higher in fruit. It thus consumes more nutrients, which results in less time needed for food acquisition. A siamang may spend an entire day in a single fruiting tree, moving out when it wants to rest and returning to feed.[12]

Siamangs are a very social species of primates and exhibit a variety of tactile and visual gestures, along with actions and facial expressions to communicate and increase social bonds within their family group.[18] They are also territorial, and interact with other family groups by making loud calls to let other groups know where their territory is. The calls may be asynchronous, where they are not directed at a particular neighbouring group, or simultaneous group calls may take place across the territory boundary. Males are known to chase one another across the boundary.[15]

Grooming frequency between males and females has been found to correlate to copulation frequency, as well as bouts of aggression. Pairs copulate over four to five months at intervals of two to three years. The peak of their reproductive activity is often during the time when fruit is most abundant.[15] Dorsoventral copulation is the most common type in siamangs, where the female is squatting and the male hangs by his arms and grips the female with his legs, whereas ventroventral copulation, where both primates are suspended, occurs only one in 60 times on average.[15]

Role of calling

[edit]
Siamang calling with throat sac inflated
Siamangs' call
Siamang, Sumatra, 2022

The siamang starts its day by calling in the early morning; it calls less after midday, with the peak of the calls around 9:00 to 10:00 am. Most of the siamang's calls are directed to its neighbours rather than to those inside its home range. This means the siamang's calling is in response to disturbances and to defend its territory. Calls in the late morning typically happen when it meets or sees another siamang group. The edge of the siamang's home range, which may overlap another, is often the place where calling is made. Counter (co-response) calling occasionally happens near the border or in the overlap area. Calls are numerous when fruit is more abundant rather than when it is less available. Branch shaking, swinging, and moving around the tree crowns accompany the calling. This movement might be to show the other groups where they are.

The siamang prefers calling in the living, tall, and big trees, possibly where another group is easy to see. Besides that, such trees can support siamang movement. Calling trees are usually near feeding trees, but sometimes they call in the feeding trees.[12][19]

Mated pairs produce loud, well-patterned calling bouts, which are referred to as duetting. These calls advertise the presence and status of a mated pair.[7] Newly formed pairs spend more time singing than an established pair. Advertising the presence of a strong bond is advantageous in territorial defense.[20] Siamang duetting differs from other species because it has a particularly complex vocal structure. Four distinct classes of vocalizations have been documented: booms, barks, ululating screams, and bitonal screams. Females typically produce long barks and males generally produce bitonal screams, but both sexes have been known to produce all four classes of vocalizations.[21] Unlike other gibbons in which vocalization is added by laterally expanded laryngeal sacs, those in siamangs fuse with each other and extend into the ventral area of the neck.[22]

Seeding

[edit]

As a frugivorous animal, the siamang disperses seeds through defecation as it travels across its territory. The siamang can carry seed while digesting, and defecate between 81.9 and 365.9 m (269 and 1,200 ft) from the seed resource, which supports the forest's regeneration and succession.[23]

Threats and conservation

[edit]

As an arboreal primate whose survival absolutely depends on the forest, the siamang faces population pressure due to habitat loss,[10] poaching, and hunting.[17][24]

Habitat loss

[edit]
Siamang, Tierpark Hellabrunn, Munich, Germany

A major threat to the siamang is habitat fragmentation due to plantations, forest fire, illegal logging, encroachment, and human development. Firstly, palm-oil plantations have removed large areas of the siamang's habitat in recent decades. Since 2002, 107,000 km2 of oil palm have been planted,[25] which has replaced much rainforest in Indonesia and Malaysia, where the siamang originally lived. Secondly, in the second decade of the 21st century, forests in the Malay Peninsula have been destroyed due to illegal logging. Sixteen out of the 37 permanent forest reserves in Kelantan, in the Malay Peninsula, where most of the siamangs live, have been encroached upon by illegal loggers.[26] Thirdly, forest encroachments change forest cover into cultivated land; for example, the rising price of coffee in 1998 encouraged people in Sumatra to replace the forest with coffee plantations.[27] Fourthly, development in many areas requires infrastructure, such as roads, which now divide conservation areas and have caused forest fragmentation and edge effects.

Poaching and hunting

[edit]

Unlike other parts of Asia, primates are not hunted for their meat in Indonesia. They are hunted for the illegal pet trade, with hunters preferring infant siamangs. Poachers often kill the mothers first, since siamang females are highly protective of their infants, and removing the infant without first killing the mother requires more effort. Most siamangs on the market are infants, which often die during transportation.[17][24]

Conservation

[edit]

Siamang can be found in at least 11 protected areas:

Indonesia
Malaysia
Thailand

References

[edit]
  1. ^ Groves, C. P. (2005). "Order Primates". In Wilson, D. E.; Reeder, D. M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 181. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ^ a b K. Suraprasit, J.-J. Jaegar, Y. Chaimanee, O. Chavasseau, C. Yamee, P. Tian, and S. Panha (2016). "The Middle Pleistocene vertebrate fauna from Khok Sung (Nakhon Ratchasima, Thailand): biochronological and paleobiogeographical implications". ZooKeys (613): 1–157. Bibcode:2016ZooK..613....1S. doi:10.3897/zookeys.613.8309. PMC 5027644. PMID 27667928.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ a b Nijman, V.; Geissmann, T.; Traeholt, C.; Roos, C.; Nowak, M.G. (2020). "Symphalangus syndactylus". IUCN Red List of Threatened Species. 2020: e.T39779A17967873. doi:10.2305/IUCN.UK.2020-2.RLTS.T39779A17967873.en. Retrieved 19 November 2021.
  4. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  5. ^ "siamang". Lexico. Archived from the original on 2022-04-26. Retrieved 2022-04-26.
  6. ^ "Definition of siamang | Dictionary.com". www.dictionary.com. Retrieved 2022-02-14.
  7. ^ a b Geissmann, Thomas. "Gibbon Systematics and Species Identification". Retrieved 2006-04-13.
  8. ^ Gron KJ. 2008 May 20. Primate Factsheets: Siamang (Symphalangus syndactylus) Taxonomy, Morphology, & Ecology . http://pin.primate.wisc.edu/factsheets/entry/siamang>. Accessed 2015 June 9.
  9. ^ a b c d Rowe, Noel. (1996) "Pictorial Guide to the Living Primates" Charlestown, RI: Pagonia Press
  10. ^ a b c O'Brien, T.G.; M.F. Kinnaird; A. Nurcahyo; M. Iqbal & M. Rusmanto (2004). "Abundance and Distribution of Sympatric Gibbons in a Threatened Sumatran Rainforest". International Journal of Primatology. 25 (2): 267–284. doi:10.1023/B:IJOP.0000019152.83883.1c. S2CID 32472118.
  11. ^ a b c O'Brien, T. G.; M. F. Kinnaird; A. Nurcahyo; M. Prasetyaningrum; Dan M. Iqbal (2003). "Fire, demography and persistence of siamangs (Symphalangus syndactylus: Hylobatidae) in a Sumatran rainforest". Animal Conservation. 6 (2): 115. doi:10.1017/S1367943003003159. S2CID 86035086.
  12. ^ a b c d Nurcahyo, A. (2001). Daily Ranging, Home-Range, Foods, Feeding and Calling in Siamang (Hylobates syndactylus). In WCS-IP 2001. Bukit Barisan Selatan National Park in Space and Time. 2000 -2001 Research Report. WCS-IP/ PHKA, Bogor. 35–52. (In Indonesian)
  13. ^ Fleagle J. G. (1988). Size and Adaptation in Primates. In Jungers WL (ed). "Size and Scaling in Primate Biology". New York: Plenum Press.
  14. ^ a b c Lappan, Susan. (2008). "Male Care of Infants in a Siamang (Symphalangus syndactylus) Population including Socially Monogamous and Polyandrous Groups". Behavioral Ecology and Sociobiology. 62(8): 1307–1317.
  15. ^ a b c d e Chivers, David J. (1976). Communication within and between family groups of siamang (Symphalangus syndactylus). Behaviour 57 (1-2): 116-135.
  16. ^ Palombit, Ryne A. (1996). “Pair Bonds in Monogamous Apes: A Comparison of the Siamang, Hylobates syndactylus, and the White-Handed Gibbon Hylobates lar. Behaviour. 133 (5) 321-356.
  17. ^ a b c Nijman, V. (2005). In Full Swing: An Assessment of Trade in Orang-Utans and Gibbons on Java and Bali, Indonesia. A Traffict Southeast Asia Report. Traffic Southeast Asia
  18. ^ Liebal, Pika, and Tomasello. (2004). “Social Communication in Siamangs (Symphalangus syndactylus): use of gestures and facial expressions” Primates. 45(1): 41-57.
  19. ^ Kinnaird, M. F.; O’Brien, T. G.; Nurcahyo, A. & Prasetyaningrum, M. (2002). "Intergroup spacing and the role of calling among siamangs". Proceedings of the XIX Congress of the International Primatological Society (Abstract).
  20. ^ Geissmann, Thomas (1986). "Mate Change Enhances Duetting Activity in the Siamang Gibbon (Hylobates syndactylus)". Behaviour. 1 (96): 17–27. doi:10.1163/156853986x00199.
  21. ^ Geissmann, Thomas (1999). "Duet Songs of the Siamang, Hylobates Syndactylus: II. Testing the Pair-Bonding Hypothesis during a Partner Exchange". Behaviour. 8 (136): 1005–1039. doi:10.1163/156853999501694. S2CID 54736136.
  22. ^ Koda, Hiroki; Nishimura, Takeshi; Tokuda, Isao T.; Oyakawa, Chisako; Nihonmatsu, Toshikuni; Masataka, Nobuo (2012). "Soprano singing in gibbons". American Journal of Physical Anthropology. 149 (3): 347–355. doi:10.1002/ajpa.22124. ISSN 0002-9483. PMID 22926979.
  23. ^ Adyn, M.F.; Sibarani, M.C.; Utoyo, L.; Surya, R.A.; Sedayu, A. (April 2022). "Role of siamang (Symphalangus syndactylus) as seed dispersal agent in a Sumatran lowland tropical forest". Biodiversitas. 23 (4): 2101–2110. doi:10.13057/biodiv/d230445. ISSN 1412-033X. S2CID 248447919.
  24. ^ a b Nursahid, R. and Bakdiantoro, H. (2005). Illegal Primate Trade in Indonesia. Profauna Indonesia. Presentation in SEAPA 1st Congress.
  25. ^ Palmer, C. E. The Extent and Causes of Illegal Logging: An Analysis of a Major Cause of Tropical Deforestation in Indonesia. CSERGE Working Paper.
  26. ^ "Illegal logging detected in 16 Kelantan forest reserves". malaymail.com. Malay Mail. 7 December 2020. Retrieved 17 January 2021.
  27. ^ Kinnaird, M.F.; Sanderson, E.W.; O'Brien, T.G.; Wibisono, H.T. & Woolmer, G. (2003). "Deforestation trends in a tropical landscape and implications for endangered mammals". Conservation Biology. 17: 245–257. doi:10.1046/j.1523-1739.2003.02040.x. S2CID 59583614.
[edit]
Wikimedia Commons has media related to Siamang.
Wikispecies has information related to Symphalangus.
Wikispecies has information related to Siamang.
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=Siamang&oldid=1262995954"