As the least studied bear species, comparatively little is known about the Malayan sun bear. It is an opportunistic omnivore, using its long tongue to eat termites and ants, beetle larvae, bee larvae, honey and a large variety of fruit species, especially figs (Ficus species) (4) (7) (8). Occasionally, it will also eat small rodents, birds and lizards (8). During periodic mass-fruiting events, fruit makes up most of the diet, providing the opportunity for sun bears to build up, or recover, fat and energy reserves for the prolonged period of low fruit availability following these events (9). The sun bear is mainly diurnal, spending most day hours foraging, although in human-disturbed areas it becomes more nocturnal (6) (10). Unlike other bears, it does not hibernate, as food is available year round (11).
Little is known about sun bear reproduction and cub rearing in the wild. Usually females are only seen with one cub and very rarely with two after a gestation period of approximately 95 days (4) (6) (12). It is possible that sun bears, like other bears, may have delayed implantation to ensure that cubs are born when the mother has sufficient fat reserves, the weather is favourable, and seasonally important foods are available, however this is not known (6). Sun bears give birth in dens or hollow trees where the cub is born naked and helpless. It remains protected for some period of time until it is able to venture out to accompany the mother while she forages and travels (6). It is thought that the cubs remain with their mother until they are fully grown at around two years old (12).
The Malayan sun bear has very loose skin around the neck so that if bitten on the back of the neck by another bear, a tiger or clouded leopard, the bear can turn in its skin to bite back of its attacker (11).