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When do orangutans use brachiation to move through trees?

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An illustration of a female Bornean orangutan (Pongo pygmaeus) with long reddish-brown fur, hanging from tree branches with one arm extended upward and one leg hooked over a branch. A scale bar at the bottom shows lengths of 30 centimeters and 12 inches for size reference. — orangutan Female orangutans (*Pongo*) have the longest breeding interval of any mammal, giving birth on average once every eight years.

Orangutans are primarily arboreal animals that spend the vast majority of their time in the trees. While they typically travel through the forest canopy by scrambling using all four limbs, they occasionally use brachiation—a form of locomotion where an animal swings from one hold to another using only its arms—to move through the trees.1

Although orangutans possess anatomical adaptations for this movement, such as proportionately long arms and flexible shoulder and hip joints, they do not rely on it as their primary mode of travel. Instead, this swinging behavior is used occasionally as they navigate their environment.1