Why do orangutans spend most of their waking hours in 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 the largest arboreal animals, and they spend more than 90 percent of their waking hours in the trees because they are highly adapted to life in the forest canopy.1

Their anatomy is specifically suited for this environment, featuring proportionately long arms, hooklike hands with long fingers, and feet with opposable big toes that facilitate climbing and movement. Additionally, they possess flexible hip joints that allow for similar range of motion in their legs and arms, which is a key arboreal adaptation for navigating the canopy. While they are capable of moving on the ground, they are slow and less efficient there compared to their agility in the trees.1