Physical description 

Sumatran rhinos are the smallest of the living rhinoceroses and the only Asian rhino with two horns.

They are covered with long hair and are more closely related to the extinct woolly rhinos than any of the other rhino species alive today. Calves are born with a dense covering that turns reddish brown in young adults and becomes sparse, bristly and almost black in older animals.

The front horn is usually 25-80 cm long, while the posterior horn is usually quite small and often no more than 10 cm.

Adult males grow to between 2-4m in length and reach up to 1-1.5m in height. They can weigh as much as 950kg, considerably less than their larger relatives elsewhere in Asia and Africa.
 

Life cycle

Sumatran rhinos prefer lower altitudes, especially secondary forests where low-growing plants are more abundant. Their habitat ranges from lowland swamps to montane forests, but they generally favour forests with thick vegetation.

In the wild, Sumatran rhinos live at low densities and are mostly solitary. Females are thought to be territorial and to avoid one another. Adults of both sexes regularly mark their ranges with scrapes, saplings, faeces, and urine.

Females are thought to reach sexual maturity at 6-7 years, while males reach sexual maturity at 10 years.

Sumatran rhinos give birth to one calf at a time, every 3-4 years. Calves are born from October to May, which corresponds with the region's rainy season. Calves gain independence at 16-17 months and may join other juveniles before taking up a solitary lifestyle.

Their life span is thought to be similar to other rhinos at around 35-40 years.

The Sumatran rhino is a browser and feeds on fruit (especially wild mangoes and figs), leaves, twigs, and bark. Sometimes the animal will venture into cultivated areas to eat crops.

Population & distribution

The Sumatran rhino once roamed from the foothills of the eastern Himalayas in Bhutan and India, through Myanmar, Thailand, possibly to Vietnam and China, and south through the Malay Peninsula.

The species is found now in small populations on the island of Sumatra in Indonesia. These scattered populations are mainly confined to Gunung Leuser, Kerinci-Seblat and Bukit Barisan Selatan National Parks. A few are also still living in Kalimantan.

The species was officially declared extinct in the wild in Malaysia in August 2015.

Overall, Sumatran rhino numbers are thought to have at least halved between 1985 and 1995, with the total number of individuals now estimated at fewer than 100.

Major threats

Habitat loss due to forest conversion for agriculture and human settlements is threatening to push the Sumatran rhino towards extinction. Most populations are very small and isolated - and may not be viable unless connecting corridors are maintained or created.

Bukit Barisan Selatan National Park in Sumatra in Indonesia, which is now estimated to have the largest single population of Sumatran rhinos, is still losing forest cover due to conversion of forest for coffee and rice production by illegal settlers.

Sumatran rhinos are known to use logged areas where there is an abundance of regenerating plants. However, the construction of logging roads makes areas more accessible to poachers.

And poaching is another major threat to the species. Rhino horn is still used in traditional Asian medicine for the treatment of a variety of ailments, even though the trade is illegal and despite efforts to reduce demand. In Vietnam, rhino horn is also bought as a status symbol.

The third threat comes from the species declining genetic diversity. No single Sumatran rhino population is estimated to have more than 75 individuals, making them extremely vulnerable to extinction due to natural catastrophes, diseases and inbreeding.