Sumatran rhinoceros

Photograph by Joel Sartore, National Geographic Photo Ark
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A Sumatran rhinoceros photographed at Cincinnati Zoo in Ohio.

Photograph by Joel Sartore, National Geographic Photo Ark

What is the Sumatran rhinoceros?

The two-horned Sumatran rhinoceros shares the bleak distinction of world’s most endangered rhino with its regional cousin, the Javan rhino, both species of which are listed as critically endangered.

The smallest of the five living rhino species, the Sumatran rhino’s hide is dark red-brown in color and covered with patches of short, dark, stiff hair. The hair helps keep mud caked to the body, which cools its skin and protects it from insects.

The Sumatran rhino’s two horns are considerably smaller than those of their African relatives, the black rhinos and white rhinos. The front horn may grow up to 31 inches but is normally much smaller, while the posterior horn may grow up to three inches but is generally no more than a hump.

Habitat

Sumatran rhinos once could be found throughout Southeast Asia, particularly in the dense mountain forests of Indonesia, Malaysia, Thailand, and Myanmar, as well as the foothills of the Himalayas in Bhutan. Now, however, the only remaining viable population lives in isolated pockets of Indonesia, mainly on the island of Sumatra.

Diet and behavior

Sumatran rhinos are solitary creatures that feed on fruit, twigs, leaves, and shrubs. Their favorite foods include wild mangoes, bamboos, and figs. They also seek out salt licks and will visit their favorites every month or two.

Like other rhinos, they have a keen sense of smell and sharp hearing, and they leave a network of scented trails throughout the forest in order to find one another.

These rhinos travel by night. By day, they can be found wallowing in ponds and other shallow, muddy waters. This helps keep them cool and prevents their skin from cracking or drying out. They’re decent swimmers, fast runners, and even adept climbers, getting up and down steep slopes with ease.

They communicate with whistling and whining noises, as well as by kicking around their dung.

Threats to survival

The International Union for Conservation of Nature classifies the species as critically endangered. Sumatran rhinos' iconic horns have been their downfall. Though they’re made of nothing more than keratin—the same material that makes up your fingernails and hair—rhino horn is believed to have medicinal uses in traditional Chinese medicine. The horn is also valued in the Middle East, Yemen especially, and North Africa as an ornamental dagger handle.

Though poaching is what caused their numbers to plummet, isolation is now the biggest threat Sumatran rhinos face. Their numbers have decreased more than 70 percent in the past 20 years and, in 2019, they were declared extinct in the wild in Malaysia. Researchers estimate there are fewer than a hundred Sumatran rhinos left in the wild. Those dwindling numbers mean they must travel farther than ever to find a mate and reproduce. Worse, if females go too long without mating, they can develop cysts and fibroids that make them infertile.

Conservation

Legally protected across their range, Sumatran rhinos are also the focus of an extensive international cooperation program. Rhino Protection Units guard the regions in which they live to prevent further poaching, while attempts at captive breeding to rebuild their population continue. Scientific breakthroughs led to the births of three calves at the Cincinnati Zoo in the early 2000s. But despite these efforts, the global population continued to dwindle.

In 2018, the world’s leading conservation organizations, including the National Geographic Society, launched an alliance to save the species, in partnership with the Indonesian government. The Sumatran Rhino Rescue captures wild rhinos and relocates them into sanctuaries where scientists can assist them to safely reproduce. Time will tell whether these efforts can save the Sumatran rhino but, as experts point out, it’s giving the species a chance to survive.


WATCH: Baby Sumatran Rhino Is Indonesia’s First Born in Captivity

Recently declared extinct in Malaysia, this rhino is now found primarily on the island of Sumatra, in Indonesia. The young calf shown in this video was filmed at the Sumatran Rhino Sanctuary in Way Kambas National Park in 2012, just a few weeks after he became the fourth Sumatran rhino born in captivity in modern times.