During the heat of the day, the Sumatran rhinoceros spends most of its day wallowing in pools of rainwater or other muddy pits, which have often been dug, or deepened, by the rhino itself (2). The rhino will often have cleared the area surrounding the wallow of vegetation, providing space in which to rest (2). This wallowing behaviour is thought to either cool the animal, or provide protection against insects (2). The Sumatran rhinoceros becomes more active in the cool of the night, and it feeds before dawn and after sunset, searching out fruits, bamboo, leaves, twigs and bark to eat. Sometimes is may also eat crops (2). For such a huge animal, it can tackle steep slopes with surprising agility and is even capable of swimming (2).
The Sumatran rhinoceros is an elusive animal, possibly due to its rarity, and its presence is most often detected by the tracks it leaves behind, rather than being sighted (7); as a consequence, details of its life history are scarce (1). The Sumatran rhinoceros is a largely solitary animal, although females are often found accompanied by their offspring. Each rhino has a permanent home-range, that includes a salt lick, and males will visit a female’s territory for mating (2). It is thought that the gestation period is probably 15 to 16 months (1), with most births taking place during the period of heaviest rainfall, from October to May (2). The calf will typically stay with its mother until 16 to 17 months of age. The Sumatran rhinoceros is thought to begin to breed at seven or eight years old, with a gap of at least three to four years between each birth (2).