The Sumatran rhino is a browser and feeds on fruit, leaves, twigs and bark. They are particularly fond of bamboo, figs and mangoes. Sumatran rhinos consume approximately 50 kg of vegetation daily and tend to feed in the cool of the early morning and late evening.
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. Populations formerly occurred in Thailand, Peninsular Malaysia, and Sumatra (Indonesia), however the subspecies currently occurs only in parts of Sumatra and Peninsular Malaysia.
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.
During the day, Sumatran Rhinos relax in mud wallows and ponds to keep cool and repel insects. They feed in the cool just before dawn and after dusk and move during the night. Seasonal movements have been recorded, with animals moving to higher elevations during the rainy season, and down to the valleys during the cooler months. They can manoeuvre on steep slopes with skill, and are competent swimmers. Sumatran rhinos are dependent on salt-licks, with a population density of 13-14 animals per square kilometre in the areas surrounding a salt-lick. Both sexes mark their ranges with scrapes, excrement, and bent saplings.