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Why do adult male orangutans make long calls?

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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.

Adult male orangutans produce "long calls"—a sequence of roars that can last up to five minutes and travel up to 2 km (1.2 miles)—primarily to serve two social functions: spacing out males and attracting sexually receptive females.1

These vocalizations are made possible by a specialized throat pouch that acts as a resonating chamber. Because orangutans live in a semisolitary social organization, the long call acts as a vital communication tool to maintain distance between males while signaling availability to potential mates. Females almost never perform the full long-call sequence, and subadult males, who lack the necessary throat pouch and cheek pads, generally do not produce these calls.1