Overview
The Sumatran Rhinoceros (Dicerorhinus sumatrensis), also celebrated as the Hairy Rhino, is the smallest, most ancient, and most critically endangered rhinoceros on Earth. The sole surviving member of the ancient lineage that included the extinct ice-age woolly rhino, this gentle, reddish-brown hairy wanderer navigates the dense, mountain rainforests of Sumatra, communicating with soft whistling vocalizations that resemble whale songs.
Biology and Physical Characteristics
Dicerorhinus sumatrensis has a compact, stocky form covered in a shaggy, bristly coat of reddish-brown hair that thickens in cold montane cloud forests. It is the only Asian rhinoceros that possesses two horns: a larger nasal horn (15 to 25 cm) and a smaller posterior horn. Its hide is deeply creased with two prominent skin folds behind the shoulders and before the hind legs, and its broad, flexible three-toed feet allow it to scale steep, muddy mountain slopes with remarkable agility.
Behavior and Ecology
A solitary, stealthy rainforest browser, the Sumatran Rhino spends up to three hours a day soaking in deep mud wallows, which cool its body and coat its skin in protective clay against biting flies and parasites. It uses communal forest mineral licks (asinan) to obtain essential sodium and minerals, marking trails with dung piles, urine sprays, and scraped saplings.
Conservation and Human Impact
Classified as Critically Endangered by the IUCN, fewer than 50 Sumatran Rhinos survive in the wild, fragmented into tiny, isolated sub-populations in Way Kambas, Bukit Barisan Selatan, and Gunung Leuser national parks. Intense captive breeding programs at the Sumatran Rhino Sanctuary in Way Kambas have achieved historic breakthrough births, representing the species’ ultimate hope against extinction.
Interesting Factoid
The Sumatran Rhino is the most vocal rhinoceros in the world; it communicates through dense rainforest undergrowth with high-pitched whistling squeals and humming groans that sound astonishingly like the songs of humpback whales.