Malaysia, Indonesia


Rain forests and monsoon forests

Kings (and queens) of swing

Siamangs have slender bodies and lightweight bones for some serious swinging. These small, or lesser, apes are in the same scientific family as gibbons. Siamangs are the largest and darkest of the gibbon species and are well suited for life in a forest’s treetops. Yet there are some features on their hands and feet that make siamangs different from their gibbon brethren.

Hands and feet

Siamang hands and feet are a lot like ours. They have four long fingers and a smaller opposable thumb on their hands, and their feet have five toes like we have, but their big toe is opposable, too. The opposable thumb and toe is lacking in other members of the gibbon family. Siamangs can grasp and carry things with BOTH their hands and their feet. One other thing that sets the siamang apart physically from other gibbons is webbing between their second and third toes.

The siamang is the largest of the 14 gibbon species.
A special throat sac enhances the siamang’s call, helping make it one of the loudest of the gibbons.
A siamang’s arm span is as wide as 4.9 feet (1.5 meters).
Siamangs are one of the few primates known to form permanent pairs.

The San Diego Zoo received our first siamangs in 1928, and over the years we’ve welcomed 15 siamang babies. Today, we have Unkie, our adult male, and his mate of many years, Eloise. If there were an ape musical, Unkie would be the leading man. He arrived in San Diego from a zoo in Florida in 1986 at age 3. He and Eloise, who was born in a Northern California zoo in 1981, have been together since 1987 and can often be heard singing duets in harmony. Eloise, affectionately known as "Ellie," is the best mom a young siamang could hope to have. She's had lots of practice, having given birth to seven youngsters over the years.

In 2003, a multilevel, naturalistic exhibit to house our siamangs and orangutans together was opened, as both species are native to the tropical rain forests of Sumatra. Keepers anticipated that the siamang family might have trouble initially fitting in with the much-larger orangutans, but the siamangs surprised everyone with their assertive behavior. Unkie is quite brave and enjoys harmlessly teasing the red apes, knowing his agility can quickly get him out of the way if need be.

Enriching activities
One of the enrichment opportunities in the exhibit is an artificial termite mound. It has long tubes inside it that open out on the surface, and keepers put in treats like baby food, applesauce, or barbecue sauce. The orangutans know how to use sticks as tools to dip into the holes to get the food, much as they would do in the wild to obtain termites, ants, and honey to eat. Although siamangs don’t tend to use tools in the wild, our siamangs learned to get the treats, too, just by closely observing their exhibit mates! Other enrichment for the siamangs and their friends include fresh browse, frozen “juice-sicles,” frozen fruit, and scattered foods like raisins that they can forage for throughout the day.

Siamangs are very smart, and our keepers have trained them to offer different behaviors that make taking care of them much easier. They can present their hands, feet, or mouth, which allows keepers and veterinarians to give them checkups without using anesthesia. They are also trained to go into a crate or get onto a scale to be weighed. Because they live with the orangutans, this is also helpful in making sure they are getting the right amount of food (Unkie seems to enjoy stealing the orangutans's food!).

Be sure to watch Unkie, Eloise, and their orangutan friends daily on Ape Cam.

Siamangs, like all gibbon species, are listed as endangered. The main reason for this status is loss of habitat due to logging and agriculture. Additionally, many adults are killed so their young can be sold into the illegal pet trade, even though siamangs are a protected species. San Diego Zoo Global supports the conservation initiative of Association of Zoos and Aquariums’ Ape Taxon Advisory Group.

One of the best ways to protect habitat for siamangs is by recycling here at home. Products like glass and aluminum are made from elements in the rain forest soil, and by recycling cans and bottles, we don’t need to dig as much in these threatened areas. Reducing paper use will also help, since many of the paper products we buy here in the U.S. come from trees cut down in Indonesia.