Sun bears are omnivores whose wild diet revolves around two main food groups: fruit and insects, with the balance between them shifting dramatically depending on what the forest offers at any given time. Found across the tropical and subtropical forests of Southeast Asia, the sun bear is the smallest bear species on Earth, and its feeding habits are tuned to the rhythms of a rainforest canopy. Honey, small vertebrates, and plant matter like young shoots round out the menu, but fruit and invertebrates account for the overwhelming majority of what ends up in a sun bear’s stomach.
Fruit Comes First
When fruit is available, sun bears eat it to the near-exclusion of everything else. A study tracking foraging signs in a seasonal tropical forest in Thailand documented bears consuming at least 93 plant species from 42 families, the vast majority of which produce fleshy fruits like berries, drupes, or capsules with edible seed coatings.1Journal of Mammalogy. Foraging ecology and coexistence of Asiatic black bears and sun bears in a seasonal tropical forest in Southeast Asia That is a remarkably wide fruit palette for any single species. Sun bears climb trees constantly to reach ripe fruit, and about 80% of all trees they were observed climbing belonged to families known to produce food they target.
The fruits sun bears favor tend to be whatever the forest is producing in abundance at that moment. They are not picky specialists locked into a handful of tree species. Instead, they track fruiting across the landscape, switching between food trees as different species come into season. A few nut-producing families like oaks and some legume pods also show up in the diet, but soft, energy-rich fruit dominates whenever the trees cooperate.
Insects as the Reliable Backup
Insects are the second pillar of the sun bear diet, and during lean fruit periods they become the primary food source. Scat analysis from Namdapha Tiger Reserve in northeastern India found that beetles (order Coleoptera) were the single most frequently occurring food item across all seasons.2Wildlife Biology. Dietary preference of Malayan sun bear Helarctos malayanus in Namdapha Tiger Reserve, Arunachal Pradesh, India Termites and ants (orders Isoptera and Hymenoptera) also featured heavily. In total, 15 insect families turned up regularly in sun bear scats from that study area, with 14 of those identified as staple food items rather than incidental consumption.
Sun bears use their long, slender tongues to extract insects and larvae from deep inside tree cavities, rotting logs, and underground colonies. This foraging style is distinctive among bears. While other bear species certainly eat insects, sun bears appear to rely on them more consistently. In the Thai forest study, fresh foraging signs related to insect feeding were roughly three and a half times more common for sun bears than for Asiatic black bears sharing the same habitat.1Journal of Mammalogy. Foraging ecology and coexistence of Asiatic black bears and sun bears in a seasonal tropical forest in Southeast Asia
Honey and Bee Products
The sun bear’s common name in several languages translates to “honey bear,” and the reputation is well earned. Wild bee nests, including both the honey and the protein-rich larvae and wax inside them, are a prized food. Sun bears will climb high into the canopy or tear apart tree trunks to access stingless bee and honeybee colonies, and their thick fur and loose skin are thought to offer some protection against stings during these raids.
Bee products straddle the line between the fruit and insect categories in a nutritional sense: honey delivers quick sugar energy similar to ripe fruit, while the brood comb provides fat and protein like other invertebrate prey. In forests where bee colonies are abundant, this can be a meaningful part of the diet. The Thai forest study counted trees climbed specifically to consume bees as a separate category from fruit-foraging climbs, suggesting researchers recognized it as a distinct and frequent enough behavior to warrant its own tracking.1Journal of Mammalogy. Foraging ecology and coexistence of Asiatic black bears and sun bears in a seasonal tropical forest in Southeast Asia
How Mast Fruiting Flips the Menu
The most dramatic dietary shifts sun bears experience are tied to a phenomenon called mast fruiting, when hundreds of tree species across a tropical forest fruit simultaneously in enormous quantities. In the Dipterocarp forests of Borneo, these masting events are linked to El Niño climate cycles and happen irregularly, sometimes with gaps of several years between events.
Research in East Kalimantan, Indonesia, captured just how extreme the swing can be. During a mast fruiting period, nearly 100% of the sun bear diet consisted of fruit. The bears gorged on mast species and largely ignored even non-mast trees that were also fruiting at the same time, suggesting a strong preference for the energy-dense mast fruits.3Biological Journal of the Linnean Society. Frugivory in sun bears (Helarctos malayanus) is linked to El Niño-related fluctuations in fruiting phenology, East Kalimantan, Indonesia Then, in the twelve months following the 1998 masting event, fruit virtually disappeared from the diet. Every scat sample collected during that post-mast period contained mainly insect remains. The bears had flipped from almost pure frugivory to almost pure insectivory within the span of a few months.
This boom-and-bust cycle has real consequences. During the fruit-rich masting phase, sun bears can build fat reserves. During the long intermast periods, they fall back on the steady but presumably less calorie-dense resource of insects. Unlike temperate bears, sun bears do not hibernate, so they cannot sleep through the lean months. They have to keep foraging year-round, which makes the insect component of the diet not just supplementary but essential for survival between masting events.
Occasional Animal Prey
Sun bears are classified as carnivores by taxonomy, and while their diet is dominated by plant matter and invertebrates, they do eat vertebrate prey on occasion. The Namdapha scat study recorded remains of rodents and fish (class Osteichthyes) alongside the far more common insect and plant matter.2Wildlife Biology. Dietary preference of Malayan sun bear Helarctos malayanus in Namdapha Tiger Reserve, Arunachal Pradesh, India Scorpions (class Arachnida) also turned up. Whether the bears actively hunt these animals or simply consume them opportunistically when encountered during other foraging is not entirely clear from scat data alone.
Anecdotal reports from across the sun bear’s range mention them occasionally eating bird eggs, lizards, and other small animals. These items appear to be genuinely opportunistic rather than targeted. Sun bears lack the body size, speed, and predatory adaptations of large carnivores, and there is no evidence they regularly pursue vertebrate prey the way, say, a brown bear might chase salmon. The vertebrate portion of the diet is better understood as incidental protein than as hunting behavior.
Built to Tear Open Trees
Several of the sun bear’s physical features make more sense once you understand how much of its feeding involves ripping into wood. Their front claws are long, curved, and exceptionally strong relative to their body size, well-suited for tearing apart rotting logs and prying open termite mounds. Their canine teeth are notably large compared to other bears of similar size, and morphological analysis suggests these oversized canines may be an adaptation specifically for tearing open tree trunks to reach insects hidden inside.4PubMed. Feeding ecology and morphology of the upper canines in bears (carnivora: Ursidae)
Then there is the tongue, which can extend roughly 20 to 25 centimeters and is used to probe deep into narrow cavities for insect larvae, honey, and sap.5PubMed Central. The Effect of Computerized Testing on Sun Bear Behavior and Enrichment Preferences The combination of destructive entry tools (claws and teeth) and a precision extraction tool (the tongue) makes sun bears uniquely effective at exploiting food resources locked away inside trees. This is not a feeding niche most other mammals can access, which helps explain how a relatively small bear can thrive in forests shared with larger competitors.
Sharing the Forest with Asiatic Black Bears
Across much of mainland Southeast Asia, sun bears share their habitat with the larger Asiatic black bear. Both species eat fruit as their preferred food, and research in Thailand’s Thung Yai Naresuan Wildlife Sanctuary found that their fundamental habitat preferences overlap significantly: both favor evergreen forest over deciduous forest, and both key in on fruit abundance as the main factor driving where they spend their time.6PubMed Central. The Shared Preference Niche of Sympatric Asiatic Black Bears and Sun Bears in a Tropical Forest Mosaic
So how do two fruit-loving bears coexist? The answer appears to involve asymmetric competition. Black bears, being larger, tend to dominate the most fruit-rich habitat patches. Sun bears, in turn, are more likely to fall back on insects as a food source, a niche the bigger bears exploit less intensively. This does not mean sun bears are pushed entirely out of fruit-rich areas, but that the competitive pressure nudges them toward a more mixed diet than they might otherwise adopt. In places where Asiatic black bears are absent, such as certain montane forests, sun bears can be relatively common, which further supports the idea that competition shapes their dietary balance and distribution rather than some intrinsic aversion to those habitats.6PubMed Central. The Shared Preference Niche of Sympatric Asiatic Black Bears and Sun Bears in a Tropical Forest Mosaic
Logged Forests Can Be Surprisingly Good Habitat
You might assume that pristine, untouched primary forest is the best habitat for sun bears, but research from Sabah, Malaysia, tells a more nuanced story. A study comparing sun bear activity between primary forest and forest that had been selectively logged about 14 years earlier found roughly 1.8 times the density of bear-climbed trees in the logged forest.7Ecosphere. Sun bears use 14‐year‐old previously logged forest more than primary forest in Sabah, Malaysia The reason comes back to diet. Logged forests had more dead wood, which serves as habitat for wood-boring insects. Termites and bees, both important sun bear foods outside of mast fruiting years, were more abundant in the logged areas and had a measurable positive effect on sun bear presence.
This does not mean logging is good for sun bears in any straightforward sense. The finding applies to forests that had time to recover and retained enough large trees to support fruiting and nesting. Heavily degraded or cleared land is a different story. But it does challenge the assumption that only pristine forest matters. For a species whose diet includes so much invertebrate prey, the structural complexity that follows selective logging, all that dead wood and regrowth, creates a food-rich environment. The practical takeaway for conservation is that previously logged forests should not be written off as low-value habitat when planning protected areas for sun bears.
What Happens When the Forest Meets a Plantation
Sun bears are increasingly encountering oil palm plantations as Southeast Asian forests are converted to agriculture, and their dietary flexibility means they do not simply avoid these areas. Research tracking sun bears in a mixed forest-and-oil-palm landscape found that bears living in forest fragments adjacent to plantations would venture out to feed on oil palm fruits.8Biodiversity and Conservation. Survival strategies of a frugivore, the sun bear, in a forest-oil palm landscape The bears still selected large forest trees for resting and much of their other feeding, but they supplemented with the readily available palm fruit nearby.
This behavior is a double-edged sword. On one hand, it shows that even relatively small forest patches of around 2,000 hectares within large agricultural landscapes can support sun bears, especially when adjacent fruit resources exist. On the other hand, bears feeding in plantations are at higher risk of conflict with people. Plantation owners may view them as pests, and the bears are more exposed to poaching and vehicle strikes when they leave forest cover. The willingness to eat oil palm fruit keeps individual bears alive in fragmented habitats, but it also puts them in harm’s way. This dynamic is playing out across Borneo and Sumatra as forest conversion accelerates.
Sap, Shoots, and the Miscellaneous Category
Beyond fruit, insects, honey, and the occasional vertebrate, sun bears round out their diet with a scattering of other plant materials. Young palm hearts, growing tips of certain plants, and tree sap or cambium all show up in feeding records. The long tongue that serves them well for insect extraction is also used to lap up sap from damaged trees. In some areas, sun bears have been observed deliberately stripping bark to access the sugary cambium layer beneath.
These miscellaneous foods probably contribute relatively little to overall caloric intake compared to fruit and insects, but they may matter during transitional periods when neither staple is especially abundant. A sun bear emerging from a stretch of insect-heavy feeding during an intermast period might supplement with sap or young vegetation as early-fruiting trees begin to produce. The breadth of this dietary portfolio, from beetle larvae to tropical berries to tree bark, reflects a generalist strategy that keeps the species viable across a wide range of forest conditions and seasonal cycles. The Namdapha study alone documented sun bears consuming 10 plant species alongside 15 insect families, and that was from a single site with a relatively modest sample of 85 scat collections.2Wildlife Biology. Dietary preference of Malayan sun bear Helarctos malayanus in Namdapha Tiger Reserve, Arunachal Pradesh, India Across the full geographic range of the species, the true dietary list is certainly much longer.