Siamang

The Siamang (Hylobates syndactylus) is an endangered primate. “Hylobates” is literally translated to “dweller in the trees”, and that description fits these animals quite well. Because they are native to tropical rainforests, they are endangered due to these rainforests being cleared at an alarming rate.

Siamangs are found in Malaysia and Indonesia, with dwarf versions of the animals found on the islands in Sumatra. They spend most of the time in the trees of the rainforest, even sleeping on tree branches, and don’t touch ground often. They are, actually, most often found at about 80-100 feet (25-30 meters) off of the ground. When they do travel along the ground, they walk on two legs, holding their arms over their heads to help balance themselves. The most-often used means of travel, however, is swinging through the trees, hooking one wrist over a tree branch as they swing forward to hook the next available branch. They travel and live in groups that are strictly family and consist of a mated pair and their children. They are very territorial, sometimes owning a territory of over 50 acres.

Interesting Fact: During any given day, a family of Siamang can travel up to a mile (1.6 km) on their search for food.

Siamangs are covered in black, shaggy fur which is lighter around the mouth and ranges to red at the eyebrow area. They don’t have tails but have extremely long forearms and hands with an opposable thumb and opposable toe. They can carry things with their hands or their feet and are very dexterous. One of their most distinguishing features is a hairless pouch on their throats that will expand when they are vocalizing. The average adult siamang weighs approximately 18-35 pounds (8-16 kg) and is 30-35 inches (75-90 cm) tall. Their arm span is very large, reaching over 5 feet (1.5 meters).

The primary staple in the Siamang’s diet is leaves and fruit, and they seem to prefer mangoes, figs, and grapes. They have also been known to eat insects, eggs, and even birds, which they snatch out of the air mid-swing. They are often seen eating with one hand while hanging from a branch with the other. They are also very generous with their food, sharing the bounty between all members of the family.

Siamangs don’t reach sexual maturity until they are between five and eight years of age, usually staying with their family groups until they are eight and then leaving to find their own mates. It will sometimes take a young Siamang two to three years to find a suitable mate, but, once mated, they mate for life. Female siamangs usually have babies two to three years apart. The gestational period lasts about 230-235 days, and the babies are born nearly hairless, with only a small patch of hair on their heads. The babies are protected and nursed by their mothers until they are a little over a year old. After they are weaned, the father takes over and cares for the young until they are about three years old and can defend themselves. Family groups stay very close together at all times.

One of the most interesting things about the siamang is the way they communicate. Their throat pouches help add volume to their calls, and these can be heard over 3 miles (4.8 km) through the jungle. They call to other family groups, establish territories, and participate in vocal warfare. Mated pairs are also known to “sing” to each other, and each pair seems to develop a unique “song” to communicate with one another.