Orangutans, whose name translates to “person of the forest” in Malay, are great apes native to the rainforests of Borneo and Sumatra. They are unique for their predominantly arboreal lifestyle, spending over 90% of their lives in the tree canopy. This adaptation to their forest homes influences their movement and physical characteristics.
Orangutan Movement and Speed
Orangutans are not built for speed on the ground, making them notably slow terrestrial movers. An adult orangutan typically reaches speeds of only about 2.7 miles per hour (4.3 kilometers per hour) when moving on solid ground. Their slow ground speed reflects their evolutionary specialization for navigating the complex, three-dimensional environment of the rainforest canopy.
Their primary modes of travel involve swinging and climbing through the trees, where they are far more efficient. They employ a method called brachiation, swinging hand-over-hand, or engage in quadrumanous scrambling, utilizing all four limbs to move across branches. While they are often deliberate in their arboreal movements, orangutans are capable of swift maneuvers when necessary. This unhurried approach to locomotion aligns with their energy-efficient metabolism, an adaptation to the unpredictable availability of fruit in their habitat.
Physical Traits for Life in the Trees
The physical design of orangutans is a testament to their arboreal existence, yet it limits their efficiency for sustained ground running. They possess disproportionately long arms, which can be 1.5 times longer than their legs, with an arm span that can reach up to 2.2 meters (over 7 feet). These powerful limbs, along with highly flexible shoulder and hip joints, allow for an extensive range of motion, enabling them to move their legs and arms at almost any angle. This flexibility is important for gripping and traversing branches.
Their hands and feet are specialized for life in the canopy, featuring long, curved fingers and toes, along with opposable thumbs and big toes that function like hooks. This design allows them to firmly grasp branches and manipulate objects with precision. While these adaptations provide agility and strength for climbing and swinging, their relatively short, bowed legs and hand-like feet are poorly suited for efficient terrestrial locomotion.
How Orangutans Move on the Ground
When orangutans occasionally descend from the trees, their ground movement is slow, deliberate, and often appears awkward. They typically move quadrupedally, adopting a “fist-walking” or “knuckle-walking” style, where they support their weight on closed fists or extended palms. This gait, combined with their bowed legs, results in a waddling motion that is far from agile.
Orangutans generally prefer to avoid the forest floor due to increased vulnerability to predators. Moving on the ground also requires more energy compared to their specialized arboreal travel, making it an inefficient mode of transport for them. They only venture to the ground when necessary, such as when crossing fragmented forest patches or seeking food and water that cannot be accessed from the canopy.