Siamang

Siamangs live in the canopies of the tropical forests of the Barisan Mountains in Sumatra, Indonesia, and south of the Perak River in Malaysia. They are found mainly in primary and secondary forests up to 2,000m in altitude.

After a gestation period of 7 months, the female generally gives birth to one baby, but in rare cases, they can be twins. The babies cling to their mother’s belly for the first 3 to 4 months and are weaned between 18 and 24 months, which allows the female to reproduce every 2 or 3 years. The male takes part in parental care by defending the young, grooming them, playing with them, and carrying them during movements. Older sisters or brothers may also help with raising the young. In her lifetime, a female can give birth to 10 offspring. The young reach sexual maturity at around 6 or 7 years old, at which point they will start looking for a life partner.

Arboreal, they spend most of their time in the canopy, moving only with the strength of their arms, that is, by brachiation, from branch to branch. They are capable of jumping from one tree to another, making leaps of nearly 15 meters long. They are also able to hang with just one arm, effortlessly, to feed themselves with the other.

These great apes are monogamous, faithful for life, and generally do not take another partner if the first one dies. As soon as the sun rises, the pair marks their territory with vocalizations performed in duet. Extremely territorial, if an intruder crosses the boundary of the territory, both the female and the male participate in the confrontation. A chase begins in the canopy and can result in slaps and bites.

They live as a couple and also in family groups with several young of different ages.

One of the main social activities is grooming, which helps establish hierarchy. The most dominant receives more than they give. When the female is receptive, the male spends more time with her, especially during the breeding season.

Siamangs spend between 8 and 10 hours a day searching for food. Depending on their geographic location, they mainly eat fruits or leaves and supplement their diet with insects, eggs, and small mammals.

Populations living in Malaysia prefer leaves and feed on about 43 to 48% leaves, which is much more than all other species of gibbons.

It is assumed that the siamang may be preyed upon by birds of prey, snakes such as the reticulated python, or carnivores such as the panther.

The siamang population is estimated at around 22,400 individuals; however, this species is classified as endangered due to the threats it faces. Only 4% of its range is protected, which leads to rapid deforestation for timber exploitation and agricultural expansion. Between 1985 and 2007, more than 40% of its habitat on the island of Sumatra was destroyed. Furthermore, many pairs are killed in order to recover their young, which are illegally sold on the pet market.