page_title: Siamang
section_title: Role of calling
hierarchical_section_title: Siamang / Ecology and behaviour / Role of calling
caption_attribution_description: English: Location taken: Miami MetroZoo, Miami, FL USA. Names: Symphalangus syndactylus (Raffles, 1821) &#160;, Anoa de montaña, Berg-Anoa, Black And White Ruffed Lemur, Black-and-white ruffed lemur, FranÁois's langur, Ngotto guenon, Ngotto moustached monkey, Red-ruffed lemur, Siamang, Siamangas, Siamango, Siamanki, Spangled ebony langur, Sumatran siamang, Sziamang, White side-burned black langur, White-nosed moustached monkey, Лемур рыжий пушистый, Лемур черно-белый пушистый, Сиаманг, סיאמנג, سیامانگ, ชะนีดำใหญ่, სიამანგი, フクロテナガザル, 合趾猿, 큰긴팔원숭 Classification: Animalia &gt; Chordata &gt; Mammalia &gt; Primates &gt; Hylobatidae &gt; Symphalangus &gt; Symphalangus syndactylus.
context_page_description: The siamang is an 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 in height, and weighing up to 14 kg. The siamang is the only species in the genus Symphalangus.
  Two features distinguish the siamang from other gibbons. The first is that two digits on each foot—the second and third toes—are partially joined by a membrane—hence the name "syndactylus", from the Ancient Greek sun-, "united" + daktulos, "finger". The second is the large gular sac, which is a throat pouch which can be inflated to the size of the siamang's head, allowing it to make loud, resonating calls or songs.
  Two subspecies of the siamang may exist. If so, they are the nominate Sumatran siamang and the Malaysian siamang. 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.
context_section_description: 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 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, high, and big trees, possibly where another group is easy to see. Besides 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.
  Mated pairs produce loud, well-patterned calling bouts, which are referred to as duetting.  These calls function to advertise the presence and status of a mated pair. Newly formed pairs spend more time singing than an established pair. Advertising the presence of a strong bond is advantageous in territorial defense.   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.
caption: Siamang calling with throat sac inflated
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