Behaviour
.jpg) The orangutan is the only strictly arboreal ape and is actually the largest tree-living mammal in the world. Although the rest of the apes do climb and build sleeping nests in the trees, they are primarily terrestrial (spending their lives on the ground). Even the hair colour of the orangutan, a bright reddish brown, is unique in the ape world.
The orangutan has the most remarkable ability to travel through the forest treetops. Each night they will build nests out of leaves and branches in the very tops of the trees – sometimes as much as 100 feet above the ground.
Almost all of the food they eat grows in the treetops and the frequent rains fill the leaves, supplying them with drinking water. When water is difficult to find, they chew leaves to make a sponge to soak up the droplets in tree cavities. However when it rains very hard, the orangutan makes an umbrella for himself out of big leaves.
Some might say orangutans have four hands instead of two hands and two feet. These appendages make them graceful and agile while climbing through the trees but makes walking on the ground somewhat slow and awkward. This is why an orangutan is at a great disadvantage on the ground, and an orangutan rarely comes down from the treetops.
Many people are familiar with the studies that have shown chimpanzees using tools, such as termite-fishing sticks. Recent studies show that some populations of orangutans also fashion tools to aid in the difficult task of foraging for food. Orangutans have even been observed using sticks to catch fishing lines.
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Orangutans emit a variety of calls and vocalisation including the long call of the males to attract females or discourage other males and the kiss-squeak, often made when observers get too close. To hear these and other calls, visit the Zurich's University Anthropological Institute & Museum here.
For recent news articles on orangutan behaviour, click here.
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Orangutan Facts
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Photos: Sue Floyed, Fleur Butcher
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