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Dicerorhinus sumatrensisSumatran rhinoceros

By Nghi Tran

Geographic Range

Dicerorhinus sumatrensis exists in the foothills of the Himalayas of Bhutan and throughout Burma, Thailand, Malaysia to Sumatra, and Borneo. Occurrence of the species in the Indochinese countries, including Vietnam and Indonesia, has not been confirmed (Nowak 1991).

Habitat

The species can live in a variety of habitats. It is mainly found in dense forests, mountain moss forests and hilly areas close to water beds. Margins of forests and areas with dense secondary vegetation also attract these animals. Sumatran rhinos also have been sighted in coastal swamps and in the sea.(Strein 1987)

Physical Description

Dicerorhinus sumatrensis is the smallest of the five living species of rhinoceros. It is thick-statured and short-bodied with a combined head and body length of 236-318 centimeters. The animal can reach a shoulder height of 112-145 centimeters. The species can be easily recognized by the two deep skin folds encircling the body between the legs and the trunk, and its thick pelage of short stiff hairs. Two horns decorate the snout, although the frontal horn is much more conspicuous than the nasal horn. An average of 16 millimeters thick, the skin of the Sumatran rhino is thick and leathery, causing it to wrinkle at the edges. The muzzle is rounded and unwrinkled. In adults, body color is generally dark gray or brown. Its dental formula is 1/0, 0/1, 3/3, 3/3.

(Nowak 1991, Strien 1986, Strien 1987)

  • Range mass
    800 to 2000 kg
    1762.11 to 4405.29 lb

Reproduction

Due to their private habits, the mating period of this species is not known. However, it is well known that most births occur from October to May, the months of heaviest rainfall. Gestation period is estimated to be 12-16 months. During the first few days after birth, the young is hidden in dense vegetation near salt licks while the mother browses. After two months, it can be found wandering with its mother. At birth, the newborn is 60 cm high and 90 cm long, weighing approximately 25 kg. The coat of neonates is short, crisp and black, but later becomes long and shaggy. During earlier stages of development, the young may associate with one another, but they eventually become solitary. Weaning takes place at 16-17 months. Interbirth intervals last at least 3-4 years. By 7-8 years of age, the calves have reached sexual maturity.

(Nowak 1991, Foose and Strein 1995)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Average number of offspring
    1
    AnAge
  • Average gestation period
    236 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    2738 days
    AnAge

Lifespan/Longevity

Behavior

The Sumatran rhinoceros is a solitary species. Both males and females maintain permanent home ranges, but males defend a larger territory than females. As boundaries of home ranges overlap, Sumatran rhinos occasionally meet, but they do not stay together for any considerable length of time. During mating periods, males and females come together to mate and form short term bonds.

The Sumatran rhinoceros is well-known for its marking behavior. The animal marks it trails with feces, urine and soil scraps. These traces serve as visual and olfactory signals for passing rhinos. The most common method of territorial marking is a scrape made by a single movement of the hind feet into the ground, resulting in a bare patch of soil. Feces are often deposited in the scrape and urine is sprayed and splashed over vegetation. This species also delimits its territory by twisting and breaking saplings; Sumatran rhinos change directions when they encounter broken trees in their way. When disturbed or threatened by human encounters, the animals spray copious urine and defecate several times. The behavior serves to temporarily attract attention from the intruders while traveling young, if present, seek cover. In some situations, these rhinos can become aggressive and hostile.

The species is an inexhaustible walker. It feeds before dawn and before sunset, and moves mostly by night. It can also swim well. During the day, the animal is often found in rain ponds or wallows that are dug out near streams. Wallows serve to cool the animal; in addition, the mud from the wallows prevents the animal's skin from cracking and drying.

The species is known to make patterned seasonal movements. It travels along hills when the lowlands are flooded, descending when the weather is cool and relatively dry, returning to high ground to escape summer insects, particularly horse flies.

(Flinn and Tajuddin 1984, Nowak 1991, Strein 1986)

Communication and Perception

Food Habits

Dicerorhinus sumatrensis is herbivorous, consuming young saplings, leaves, and plants in secondary growth. When feeding, the animal moves in a zig-zag fashion, sampling the potential food items in sight before it takes in mouthful quantities. Young saplings serve as the major food source and are systematically prepared for consumption; the young trees are bitten off, trampled upon, and then eaten. These rhinos take in fruits, twigs, and bark. Favored foods, such as wild mangoes, bamboos, and figs are preferred. Rhinos get minerals, mainly sodium and calcium, from drinking from salt springs. Daily food consumption in adults averages 50 kilograms.

(Strien 1986)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • seeds, grains, and nuts
  • fruit

Economic Importance for Humans: Positive

Hunted for body parts that supposedly have medicinal properties.

Economic Importance for Humans: Negative

The Sumatran rhinoceros sometimes tramples agricultural land and feeds on crops.

(Flynn and Tajuddin 1984)

Conservation Status

Dicerorhinus sumatrensis is classified as endangered by the IUCN and the USDI, and is on Appendix 1 of CITES. The original range of the species has drastically decreased due to habitat destruction by logging and clearing of land for agriculture. The species is also threatened by overhunting for the suppposedly aphrodisiac and medicinal products made from the horns and other body parts of the body. In addition, it is very sensitive to all forms of disturbances and is driven out by the slightest signs of intrusion. Strien (1986) claims the species is now one of the rarest and most threatened animals. Current efforts to preserve D. sumatrensis include protection of its habitat and laws prohibiting hunting of the species.

(Strein 1986, Strein 1987)

Contributors

Nghi Tran (author), University of Michigan-Ann Arbor.

Glossary

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

tactile

uses touch to communicate

References

Flynn, R.W. and Tajuddin, A.M. 1984. Biological Conservation, vol 28(3):253-257.

Foose, T.J. and Strien, N.J. 1995. Asian Rhinos, vol 1:1-24.

MacKinnon, K. and Santiapiallai, C.1984. Tigerpaper (Bangkok), vol 20(4):23-30.

Nowak, R.M. 1991. Walker's Mammmals of the World. Fifth Edition. Johns Hopkins University Press Baltimore.

Strien, N.J. 1986. Mammalia Depicta, No.12:1-200.

Strein, N.J. 1987. Lutra, vol 29(2): 343.

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