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Tua: Female, born at Zoo Atlanta on November 4, 1992. Tua arrived at the Philadelphia Zoo on April 23, 1999.
Sugi (Sugriwa): Male, born at the St. Louis Zoo on December 31, 1995. Sugi arrived at the Philadelphia Zoo on December 15, 2006.
Batu: Female, born on October 2, 2009 to Tua and Sugi.
If you see a pile of sheets or cardboard start to move in the orangutan exhibit, it's probably an orangutan.
PECO Primate Reserve (Until further notice, the Sumatran orangutans will typically be off exhibit on Tuesday and Thursday mornings to allow the white-handed gibbons full access to the exhibit.)
The highly-intelligent orangutan is the largest tree-living mammal in the world.
Have a question about this animal?
Ask an expert on our Docent Council!
Sumatran orangutans are one of the great apes and are among the largest of all living primates. They are also among the most critically endangered - an estimated 80% of orangutan habitat has been destroyed in the last 20 years and there are only an estimated 6,600 individuals left in the wild, with numbers continuing to drop at an alarming rate.
Orangutans exhibit a pronounced physical difference between males and females. This male/female difference is called sexual dimorphism. Male orangutans exhibit a little understood phenomenon known as “bimaturism” This means that there are two types of mature male orangutans: flanged and unflanged males. Flanged males have big cheek pads on the sides of their face and a large throat sac under the chin, which aid in vocalizing. Unflanged males have neither cheek pads nor throat sacs, although they are sexually mature and able to father offspring.
Orangutans are covered with a sparse, coarse, long, shaggy hair which, in adults, can be maroon or dark reddish brown to burnt sienna in color. An adult orangutan’s face is mostly bare with dark skin. Sumatran orangutans tend to be slimmer than Bornean orangutans, with longer faces, and the fur is usually longer and lighter.
Orangutans in both the wild and in zoos may live into their late 50s, with Guarina and Guas, a pair of orangutans at the Philadelphia Zoo, holding the longevity record for orangutans at 57 and 58 years old, respectively. Wild orangutans face many threats and so their average lifespan varies widely, and most individuals do not reach the maximum lifespan.
Care of young orangutans is given exclusively by the mother. Female orangutans invest a lot in each infant. Gestation is about 9 months and the infant nurses for 4-5 years. As the infant grows, it becomes less and less dependent on its mother, but because of its heavy investment in each infant, female Sumatran orangutans may go 7-9 years between offspring.
Wild orangutans are primarily arboreal—they spend most of their time high in the trees. They are the only members of the great ape family to spend most of their time off the ground. Their legs are short, but they have long, muscular arms to help them climb. They use their hands and feet to climb, grasping and swaying their way between trees. Orangutans can also walk on two feet, but locomotion on the ground is usually quadrupedal (on four feet). They build a nest of branches and leaves in a tree each evening and also sometimes during the day.
Orangutans are the most solitary of the great apes, but they exhibit a wide range of sociality across their range and may be extremely social when they do associate with other orangutans. Generally, flanged male orangutans spend most of their time alone, while females usually travel with just their dependent infant or juvenile offspring. However, female orangutans do spend some time with other adult females, often relatives. Unflanged males (males that have not developed cheek pads) also associate with females and other unflanged males in times of food abundance. Male orangutans hold large territories that may overlap the territories of several females. Flanged males use their throat sacs to make long calls, a distinctive vocalization that can carry for almost a mile, which announce territory and attract females. Orangutans, like chimpanzees, have been shown to exhibit innovative behavior and social learning.
Male orangutans are much larger than females. Males measure, on average, 3.18 ft (970 mm) and females average 2.56 ft. (780 mm).
Males weigh, on average, 192 lbs (87 kg); females weigh an average of 81.6 lbs (37 kg).
In the wild, orangutans consume mainly fruit when it's available, but also regularly eat insects and flowers and fall back on less favored foods when fruit availability is low. Fallback foods include inner bark, young and mature leaves, and non-leafy vegetation. At the Zoo, orangutans are offered a base diet of primate biscuit. Several types of primate biscuit are included. The enrichment portion includes a variety of familiar fruits as well as seasonally available Asian fruits similar to those consumed in the wild. Vegetables, nuts, leafy greens and seasonal browse are also in the diet.
Primary and secondary forests, including peat swamps, lowland dipterocarp, and montane forests on the Indonesian island of Sumatra.
On the 2011 IUCN Red List for Threatened Species, the Sumatran orangutan is listed as Critically Endangered.
Wild orangutans are found on the islands of Sumatra and Borneo, where they spend most of their time high in the treetops. These impressive great apes depend on the diverse fruits and plants of the rainforest to survive, but illegal logging and the conversion of natural forests to oil palm plantations has destroyed much of their habitat. As a result, Sumatran orangutans (Pongo abelli) are currently listed as critically endangered with fewer than 7,000 remaining in the wild, while the number of Bornean orangutans (Pongo pygmaeus) has plummeted over the past two decades from 300,000 to less than 55,000 today.
Research teams working in Indonesia and Sumatra have been studying the ecological and biological needs of the orangutan for nearly two decades. The Philadelphia Zoo has joined the efforts of the Sumatran Orangutan Conservation Programme (SOCP) to protect this elusive primate.
Learn more about Philadelphia Zoo's orangutan conservation efforts.
Join the movement! The UNLESS Project is building a global community to save habitat for wildlife by driving demand for palm oil that is deforestation-free.
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