Sumatran orangutan

Orangutans love ripe fruit, like figs.

They also eat leaves, flowers and bark. Sometimes they eat ants and termites too.

Sumatran orangutans eat mainly fruit. Orangutans can eat up to 100 kinds of ripe fruit, and figs and durian fruit are the most common. They also eat leaves, seeds, shoots, flowers, bark and insects such as termites and ants.

When a big fig tree is full of fruit, several Sumatran orangutans may gather to feed together. As they eat fruit and travel, orangutans spread seeds over a huge area, so many trees, especially ones with large seeds, depend on them.

The IUCN describes the species as primarily frugivorous, also eating young and mature leaves, seeds, shoots, pith, flowers, termites, ants, bark and, occasionally, the meat of slow lorises. San Diego Zoo Wildlife Alliance lists up to 100 kinds of ripe fruit for orangutans, with figs and durian the most common.

WWF links the Sumatran orangutan's closer social ties to mass fruiting of fig trees, where groups can feed together, and stresses its role in seed dispersal: if orangutans disappeared, several tree species, especially large-seeded ones, would be lost too. Orangutans also strip leaves from twigs to probe holes for termites.

Grown-up male orangutans like to be alone.

Mothers and babies stay together. Every night, each orangutan makes a new leafy bed high in a tree.

Orangutans spend much of their time alone, but Sumatran orangutans are more social than their Bornean cousins. Mothers and young may feed together at a fruit tree, and young orangutans sometimes travel in small groups for a few days.

Grown-up males with cheek pads stay alone and keep away from other males. They make a loud long call that can carry about 2 kilometers. Every evening an orangutan bends branches into a new nest, and in the rain it may hold leafy branches over itself like an umbrella.

Orangutans have a semisolitary social organization, but WWF reports closer social ties in Sumatran orangutans than in Bornean ones, and San Diego Zoo Wildlife Alliance describes Sumatran adolescents, females or unflanged males traveling together for days. Flanged males remain solitary and intolerant of each other.

Female home ranges are 0.8 to 1.5 square kilometers; male ranges are not fully known but are inferred to exceed 30 square kilometers. Flanged males give the long call, amplified by the throat sac, which Britannica says can carry 2 kilometers. Orangutans build a new nest almost every night and use leafy branches to shelter from rain and sun.

There are not many Sumatran orangutans left.

People are protecting their forests. Some orangutans that were kept as pets are going back to live in the wild.

The Sumatran orangutan is critically endangered. Its forests are being cut down for oil-palm plantations, logging and new roads. Some orangutans are killed illegally, and their babies are sold as pets.

Scientists estimated in 2016 that about 13,846 are left. That is more than an older count, only because surveys got better; the real number is still falling. Rescuers are returning orangutans taken from the pet trade to the wild, and more than 260 have been released to start new populations.

The IUCN lists Pongo abelii as Critically Endangered (assessed 2017, amended 2024), projecting a decline of more than 80 percent over three generations from 1985 to 2060. Threats are oil-palm plantations, legal and illegal logging, roads that open forest to settlers and poachers, deliberate killing, the pet trade and conflict over crops. The IUCN names Aceh's 2013 spatial plan, which ignores the Leuser Ecosystem's protected status, as the largest single threat.

The 2016 estimate of 13,846 in 16,775 square kilometers of forest is higher than the 2008 figure of about 6,600 only because surveys improved; numbers continue to fall. More than 260 confiscated orangutans have been reintroduced around Bukit Tigapuluh National Park and the Jantho reserve to build new wild populations.