Sumatran Rhinoceros

The last ‘prehistoric’ rhino is now one of the world’s most endangered species 

The Sumatran rhinoceros is the last “hairy” rhinoceros left on Earth. The smallest species of rhinoceros, the Sumatran rhino may very well be the most endangered large mammal in the world today.

Incredible Sumatran Rhino Facts!

• The Sumatran rhino is believed to be the closest living relative to Wooly rhinos that were covered in fur and went extinct 8,000 years ago.

• The Sumatran rhino may be the most endangered large mammal in the world, with potentially as few as 30 individuals remaining

• Among rhinos, the Sumatran is by far the smallest species surviving today. On average, Sumatran rhinos weight just ¼ the size of white rhinos!

Sumatran Rhino Scientific Name

The scientific name of the Sumatran rhinoceros is Dicerorhinus sumatrensis. The genus Dicerorhinus is Greek for “two horns”, although the Sumatran rhinoceros is the last living species of this genus.

Samatrensis means “of Sumatra” as the species was first located on the island (though its original range stretched far beyond Sumatra).

Sumatran Rhino Appearance

The Sumatran rhinoceros is the smallest of the five rhinoceros species with a body length of less than 250cm (about 8.2 feet). At their shoulders, a Sumatran rhino is approximately 150 cm (5 feet) in height.

The smallest of all rhino species, Sumatran rhinos weigh between 500-800 kg (1,100 lbs – 1,760 lbs). It is unique among rhino species in that it has a reddish-hair that can cover a large portion of its body.

The Sumatran rhinoceros has relatively poor eyesight, relying more on hearing and smell to detect what is going on around them. The ears of the Sumatran rhinoceros possess a relatively wide rotational range to detect sounds and an excellent sense of smell to readily alert them to the presence of predators.

Sumatran Rhino Horn

The Sumatran rhinoceros uses it’s horns for defense, intimidation, digging up roots and breaking branches during feeding. The horns of the Sumatran rhinoceros are made from a substance called keratin and are therefore very strong. The horns of the Sumatran rhinoceros are used in ancient medicine and many Sumatran rhinos have been illegally hunted for them.

Unlike the other Asian rhinoceros species, the Sumatran rhinoceros has two horns like the white and black rhinos found on the African continent. However, its horns are generally much smaller than those species.

While the largest ever recorded Sumatran rhino horn measured 32 inches (81 cm), their horns generally measure less than 10 inches (25 cm) in length. The front horn of Sumatran rhinos is longer, while the back horn is often less than an inch (2.5 cm) in length.

Sumatran Rhino Behavior

The Sumatran rhinoceros is a solitary animal and only comes together with other Sumatran rhinos to mate.

Sumatran rhinos spend long portion of their day in mud wallows they utilize their feet and horns to deepen. Layers of mud not only help protect the Sumatran rhino from biting insects, but also regulate skin temperature. Sumatran rhinos kept in captivity that lacked sufficient daily wallowing suffered from chronic skin problems as a result.

The Sumatran rhino is also very diligent about marking its territory and trails through feces, urine, and even scraping trees. The large territory of each Sumatran rhino (up to 50 square kilometers for males) helps explain why sightings of these animals is so rare.

Sumatran Rhino Habitat

The Sumatran rhinoceros primarily inhabits dense lowland rainforests, tall grass and reed beds that are plentiful with rivers, large floodplains, or wet areas with many mud wallows, swamps and cloud forests. The range of Sumatran rhinoceros once stretched from India, through south-east Asia and down to Sumatra but today, the Sumatran rhinoceros is only found on the islands of Sumatra and Borneo.

Sumatran Rhino Diet

The Sumatran rhinoceros is a herbivorous animal meaning that it sustains itself on a purely plant-based diet. Sumatran rhinos browse the densely vegetated sub-tropical forest for leaves, flowers, buds, fruits, berries and roots which they dig up from the ground using their horns

Sumatran Rhino Population — How Many Sumatran Rhinos Are Left?

Today, the Sumatran rhino may be the most endangered large mammal on Earth. In 1986, the IUCN estimated there were between 425 and 800 Sumatran rhinos were left. By 2009, the International Rhino Foundation estimated its population had shrunk to as few as 250 individuals.

Today, they estimate fewer than 80 Sumatran rhinos are left, and that number could be as low as 30 individuals that live across four fragmented national parks.

While the Sumatran rhino populations today continue decreasing due to loss of habitat and poaching, the species has long been on the brink of extinction. A study from Current Biology estimated that only 700 individuals were left after major climate changes about 9,000 years ago and have struggled to rebound since.

Sumatran Rhino Predators

Due to its large size, the Sumatran rhinoceros’ only real predator in the wild are large wild cats such as tigers that will prey on the Sumatran rhino calves and weak individuals. With the Sumatran Tiger numbering no more than 500 individuals across the island and isolated into small, isolated pockets, its encounters with Sumatran rhinos today are likely rare.

Humans are the biggest threat to the Sumatran rhinoceros as they have been hunted to the brink of extinction for their horns.

Sumatran Rhino Reproduction and Life Cycles

The female Sumatran rhinoceros gives birth to a single calf after a gestation period that is over a year long (approximately 15-16 months). The Sumatran rhinoceros calf remains with its mother until it is at least 2 years old and big enough to become independent.

The longest surviving Sumatran rhino in captivity is estimated to be about 35 years of age, as of 2020. It is believed that in the wild, Sumatran rhinos can live to about 45 years of age.

Sumatran Rhinos in Zoos

In 1984 a program to capture and breed Sumatran rhinos was launched. Unfortunately, of the 46 captured for breeding purposes only five are still alive today, and only four calves were born and survive today. The last Sumatran rhino in the Western hemisphere – 8-year old Harapan – was moved back to Indonesia from the Cincinnati Zoo in 2015.

Sumatran Rhino Facts

• The most prehistoric rhino
   
  • The Sumatran rhino is the last surviving member of the Dicerorhinini group which emerged roughly 20 million years ago! It is considered the closest living relative to Wooly rhinos that went extinct approximately 8,000 years ago.

     

• Extinct in Malaysia

   

  • No sightings of the Northern Sumatran rhino, which once lived on mainland Asia have been seen since 2007. In 2019, the Sumatran rhino was declared extinct in Malaysia.

     

• Hope in Borneo: The first sighting in 40 years!

   

  • After more than 40 years without a sighting in Indonesian Borneo, a Sumatran rhino was captured and relocated for protective and breeding purposes. The rare sighting shows how remote of locations Sumatran rhinos live in. However, it’s still unclear if a viable breeding population survives on the island.

     

• Just ¼ the size of the white rhino!

   

  • As the largest of the rhino species, the White rhino can weigh up to 7,920 lbs (3,600 kg). By comparison, Sumatran rhinos weigh up to 1,760 lbs (800 kg), or only about a quarter the weight! It is believed the Northern Sumatran rhino that once roamed from India to Malaysia was larger, but with it believed to be extinct, only the smaller subspecies of Sumatran rhinos surviving in Indonesia remain today.