Sumatran rhinoceros

The Sumatran rhinoceros, known scientifically as Dicerorhinus sumatrensis, is a rare and unique mammal. It is a member of the Rhinocerotidae family. It is also the only living species in the genus Dicerorhinus. This rhino is the smallest of all living rhinoceros species.

Despite its small size compared to other rhinos, it remains a large mammal. It is critically endangered, meaning it faces a very high risk of extinction in the wild. Understanding this animal is important for studying how species survive through changing environments.

Physically, the Sumatran rhino has several distinct features. It has a coat of reddish-brown hair covering most of its body.

Unlike some other rhinos, it has two horns. The larger one is the nasal horn, also called the anterior horn. It is typically about 10 centimeters long. The second horn is the frontal horn, which is often just a small stub.

The skin is thin and has two thick folds behind the front legs. In the wild, the hair may look thin because the animals often cover themselves in mud. In captivity, the hair grows much longer and shaggier.

Scientists divide the Sumatran rhinoceros into three distinct subspecies. The first is D. s. sumatrensis, the western Sumatran rhinoceros. These rhinos live mostly in Sumatra, specifically in national parks like Gunung Leuser.

The second is D. s. harrissoni, known as the Bornean or eastern Sumatran rhinoceros. This subspecies is markedly smaller than the others. It was once common in Borneo but is now very rare. The third is D. s. lasiotis, the northern Sumatran or Chittagong rhinoceros. This subspecies was significantly larger than the others. It once lived in India and Bangladesh but is now declared extinct in those countries.

Human history with this species began in the late 18th century. The first documented specimen was shot near Fort Marlborough on the coast of Sumatra in 1793.

A naturalist named Joseph Banks published a description of this animal that same year. In 1814, Johann Fischer von Waldheim gave the species its scientific name. The term sumatrensis means "of Sumatra." Over time, different scientists proposed different names for the genus. In 1841, Constantin Wilhelm Lambert Gloger proposed Dicerorhinus. This name comes from Greek words meaning "two," "horn," and "nose." A 1977 ruling established Dicerorhinus as the official name.

Today, the numbers for this species are very low. There are estimated to be fewer than 80 mature individuals left in existence.

The western subspecies has between 75 and 85 rhinos remaining. The Bornean subspecies is even smaller, with only about 15 individuals estimated to survive. The species was declared extinct in Malaysia in 2019 after the last bull and cow died. In Borneo, researchers found a tiny population in East Kalimantan in 2016. Because the populations are so small and separated, the species is in a very fragile state.

Conservation efforts focus on both wild protection and captive breeding. Some rhinos live in the Sumatran Rhino Sanctuary at Way Kambas.

This sanctuary has successfully helped raise offspring. A bull was born there in 2012, a female calf in May 2016, and another female in March 2022. These births are vital because the species faces threats like poaching and habitat loss. Earlier attempts to bring rhinos into captivity were difficult. For nearly 20 years, no offspring were produced in those programs. Now, researchers use more specific knowledge to try and preserve the remaining animals.

Evolutionary studies show that the Sumatran rhino has a long and complex history. Genetic evidence suggests its ancestors split from the ancestors of horses about 50 million years ago.

It is more closely related to the Asian one-horned rhinoceroses than to African species. It is also believed to be closely related to the extinct woolly rhinoceros. This extinct relative lived across Eurasia and died out near the end of the last ice age. Scientists believe the Sumatran rhino's population has fluctuated for hundreds of thousands of years due to climate change and the flooding of land areas. These changes in the Earth's history have shaped the small, rare population we see today.