Sun Bears are a forest-dependent species, favouring interior mature and/or heterogeneously structured primary forests (Augeri 2005). There are two ecologically distinct categories of tropical forest that comprise their natural range, distinguished by differences in climate, phenology, and floristic composition: seasonal evergreen and deciduous forest in the mainland (north of the Isthmus of Kra) and aseasonal evergreen rainforest in Malaysia, Sumatra and Borneo.

In the far northern range limit in northeast India, Sun Bears were recorded in mountainous areas of subtropical climate (Higgins 1932, Chauhan and Singh 2006, Choudhury 2011). Their range may be limited farther north by colder climate and unsuitable habitat in the Himalayan sub-region, and limited farther northwest by competition with Sloth Bears (Melursus ursinus; Steinmetz, 2011). In Bangladesh, Northeast India, and throughout the rest of the mainland range (Myanmar, Thailand, Lao PDR, Cambodia and Vietnam) Sun Bears are sympatric with Asiatic Black Bears, inhabiting seasonal ecosystems with a long dry season (3-7 months), during which rainfall is <100 mm per month. Seasonal forest types usually occur in a mosaic that includes semi-evergreen, mixed deciduous, dry dipterocarp, and montane evergreen forest (Nguyen Xuan Dang 2006, Scotson 2010, Steinmetz 2011, Gray and Phan 2011). In Thailand, Sun Bears and Asiatic Black Bears use many of the same habitats and have extensive overlap in diet.  However, in montane forests >1,200 m elevation (where ground cover is sparse) Asiatic Black Bears are more abundant than sun bears, possibly due to the lower abundance of invertebrate prey (Vinitpornsawan et al. 2006, Steinmetz et al. 2011).

In southern Thailand and Peninsular Malaysia, Sun Bears inhabit tropical evergreen moist forest and lowland or hill dipterocarp forest (Kawanishi and Sunquist 2004, Nazeri et al. 2014). Tropical evergreen rainforest comprises the Sun Bear’s main habitat in Borneo, Sumatra, and Peninsular Malaysia. Climate is generally constant in this region, with high annual rainfall that is relatively evenly distributed throughout the year. The Sundaic tropical evergreen rainforest includes a wide diversity of forest types used by sun bears, including lowland and hill dipterocarp, peat swamp, freshwater swamp, limestone/karst hills and lower to sub-montane forest. Of these habitats, in Borneo and Sumatra, sun bear abundance (based on signs and camera trap records) was highest in primary lowland dipterocarp forest (Davies and Payne 1982, McConkey and Galetti 1999, Wong et al. 2002, Fredriksson 2005, Augeri 2005, Linkie et al. 2007, Wong and Linkie 2013). Sun Bears also occur in mangrove forest, although their occurrence in this forest type probably depends on proximity to other more favoured habitats (G. Fredriksson, pers. obs).

Broadly speaking, Sun Bears seem to be more abundant in lower elevations (Augeri 2005, Steinmetz 2011) but there is wide variation throughout the range. In India, Sun Bears were detected up to 3,000 m (Choudhury 2011) and occupancy was higher in high elevations, possibly because low elevations were more degraded (Karanth et al. 2009). In western Thailand, Sun Bears occurred primarily below 1,200 m (Vinitpornsawan et al. 2006) but have been observed up to 2,100 m in neighbouring Myanmar (Htun 2006), and up to 1,600 m in Lao PDR (Steinmetz et al. 1999). In Indonesia, sun bears occur primarily below 1,200 m although have been observed at 2,140 m in Sumatra (Augeri 2005, Wong and Linkie 2012). In Peninsular Malaysia Sun Bears were primarily below 1,200 m (Nazeri et al. 2014), whereas in Sarawak (Malaysian Borneo) Sun Bears were more frequently encountered at higher altitudes, though this might be the result of high levels of hunting and logging activities at lower altitudes, both having negative impacts on Sun Bear densities (Brodie et al. 2015).

In highly disturbed landscapes, habitat use may be driven more by hunting and habitat disturbance levels than by natural influences. For example, in the World Heritage Dong Phayayen-Khao Yai forest complex in Thailand, illegal rosewood (Dalbergia spp.) logging may cause Sun Bears to avoid interior forest, due to intensive logger traffic, most of whom are armed with guns (D. Ngoprasert, King Mongkut's University of Technology, pers. comm.). In some sites Sun Bears seem to prefer interior primary forest and density increases with increasing distance to roads and human settlements (Linkie et al. 2007, Nazeri et al. 2012, Wong and Linkie 2013). However, sun bears also use selectively logged areas (Wong et al. 2004, Meijaard et al. 2005, Linkie et al. 2007), but their occurrence in newly logged forest (<10 years) is much lower compared to forest that was logged more distantly in the past (Brodie et al. 2015).

Sun Bears have been observed in plantations (oil palm, sugar palm), agricultural lands (sweetcorn, cucumber, pumpkin, sesame), orchards (coconut, durian, banana, jackfruit, snakefruit, pineapple, apple) and near forest edges (Nomura et al. 2004, Augeri 2005, Fredriksson 2005, Wong et al. 2012, Chea 2013, Sethy and Chauhan, 2013, Scotson et al. 2014), where they may be considered pests. Scattered reports of predation on livestock (goats; Sumatra, Wong et al. 2015) and chickens (Borneo, Fredriksson 2005) exist. Crop raiding tends to occur most often during harvest time and is concentrated in areas where crops are planted along the forest edge (Santiapillai and Santiapillai 1996, Fredriksson 2005, Scotson et al. 2014). There is no evidence that Sun Bears can survive in deforested or agricultural areas in the absence of nearby forest (Augeri 2005). It is known that they can derive some nutritional benefit from consuming oil palm fruits (Nomura et al. 2004, Chea 2013), but it is doubtful that they could subsist on this, without other foods and cover provided by nearby natural forest.

Sun Bears are generalist omnivores, feeding primarily on termites, ants, beetle larvae, stingless bee larvae and honey, and a large variety of fruit species. Figs (Ficus spp.) are particularly important when available (McConkey and Galetti 1999, Wong et al. 2002, Augeri 2005, Fredriksson et al. 2006a). Occasionally, growth shoots of certain palms and some species of flowers are consumed (Fredriksson et al. 2006a), but otherwise vegetative matter rarely occurs in the diet. The Indonesian name for Sun Bears translates to ‘honey bear’ presumably because they are so attracted to honey. Their massive jaw muscles and disproportionately large canines (for the size of their head; Christiansen 2007, 2008) enable them to bite through the bark/stem of hardwood trees to consume stingless bees nests and honey, and their long tongues are used to extract insects and their products from crevices. Their long sharp claws enable them to dig easily into the ground and break into rotting logs (Wong et al. 2002). In Bornean lowland forests, fruits of the families Moraceae, Burseraceae and Myrtaceae make up more than 50% of the fruit diet (Fredriksson et al. 2006a), whereas in western Thailand fruits of Lauraceae, Fagaceae, Leguminosae, Labiatae, and Sapindaceae are the most commonly consumed (Vinitpornsawan et al. 2006, Steinmetz et al. 2013).

There is no evidence of Sun Bears hibernating, presumably because of year-round food availability across their range. There is also no evidence of parturient females entering a prolonged period of fasting, as do other bears species. Female bears use cavities of either standing or fallen large hollow trees as birthing sites. Both diurnal and nocturnal behaviour has been documented. Average home range estimates from Borneo and Peninsular Malaysia range from 7 km² to 27 km², respectively, with daily movements affected by food availability (Wong et al. 2004, Fredriksson 2012, Cheah 2013).

Little is known about social structure or reproduction. Sun Bears are largely solitary, except when with offspring. But they occasionally occur in pairs, and may congregate to feed from large fruiting trees. Faecal steroids from wild Sun Bears in Indonesia and from captive Sun Bears in European and American zoos indicated that Sun Bears are polyestrous, a seasonal breeders, usually producing a single cub (Schwarzenberger et al. 2004, Frederick et al. 2012).

Measures to reduce habitat loss and poaching throughout the entire Sun Bear range are key actions needed to conserve Sun Bears. In areas with the highest deforestation rates, such as Indonesia and Malaysia (two globally leading oil palm producers), immediate action should be taken to protect remaining high conservation value forests from conversion to other land-uses, eliminate unsustainable logging, and effectively manage forest fires. Additionally, new protected areas should be established and effectively managed in order to preempt land conversion (Augeri 2005, Tumbelaka and Fredriksson 2006, Wong 2006) and protect critical Sun Bear habitat. For example, in Peninsular Malaysia, Nazeri et al. (2012), using MaxEnt modelling, reported that Sun Bears favour dense tropical evergreen forest over cultivated landscapes and areas in close proximity to roads. Of habitat deemed ‘highly suitable’ only 22% is contained within protected areas. These findings suggest that the present geographical extent of protected areas in Peninsular Malaysia provide insufficient coverage of habitat crucial for conserving Sun Bears.

In conjunction with primary forest protection, degraded habitats and forest remnants in human-modified landscapes should be enhanced, through reforestation programs, corridor planning and elevated protected status. Additionally, there is the need to establish buffer zones and prevent further agricultural expansion surrounding protected areas. Achieving these measures requires increased levels of resources, the support of conservation constituencies in civil society, and strengthened government commitments to conservation. In Malaysia and Indonesia, the two main producers of palm oil, it will be difficult to stop forest conversion, given the impacts of their economies in the world markets. Furthermore, in present conditions the effective management of already established protected areas, let alone addition of new protected areas and land management outside of protected areas, has proven a highly challenging task.

Sun Bears are legally protected domestically and internationally from hunting and trade throughout most of their range. However, deficiencies in law enforcement are recognized as major ongoing weaknesses (Burgess et al. 2014). Some successes are evident where dedicated agencies operate with steady technical and funding support. For example, in Cambodia, a dedicated Wildlife Protection Mobile Unit, run by Forestry Officials and Military and funded by international NGOs, has confiscated more than 100 Sun Bears and Asiatic Black Bears since 1998 (Broadis 2011). Similar initiatives exist in parts of Malaysia and Indonesia but action is limited. Establishment of more focused wildlife protection/crime units is recommended for other range countries, where possible funded by local authorities responsible for wildlife law enforcement.

Reduction of mortality by clearing of snares from bear habitat is urgently needed throughout much of the range, and long term measures are needed to prevent the problem reoccurring. Efforts to do so are underway in several protected areas throughout the region, by park authorities often in collaboration with foreign NGOs. However, these projects usually do not extend throughout a protected area and can face difficulties in maintaining long-term funding and political support.

To combat the growing impacts of human-bear conflict, funding and technical support is needed to promote non-lethal mitigation, especially in low-income regions where the incentive to hunt bears may outweigh incentives to stop conflict from occurring.

Non-government organizations (NGO’s) have established bear dedicated rescue centres in Cambodia, Vietnam, Lao, Thailand, Malaysia and Indonesia with the primary aim of providing sanctuary to bears confiscated from the illegal wildlife trade. Bear rescue centres can play a key role in raising local awareness on the threats to sun bears and the conservation value of ecological services provided by bear habitat. Some centres operate dedicated outreach teams, providing structured learning programs that can reach tens of thousands of people each year. Likewise, centres support capacity building of local conservationists, and facilitate in-situ and ex-situ research and conservation. Rehabilitation of ex-captive Sun Bears is another potential role. However this is rare and fraught with challenges, as most potential release sites are still threatened by forest loss and poaching. For example, in Cambodia, a pilot project to rehabilitate two Sun Bears that had been confiscated from the illegal wildlife trade ended after both bears were trapped in snares within two months, despite over two years of intensive snare-patrolling in the area prior to the release (M. Hunt, Free the Bears, pers. comm).

Ultimately, reducing the trade in bear parts would be one of the most highly beneficial steps for the persistence and recovery of Sun Bears throughout their range, especially as trade is increasingly moving towards the last strongholds for Sun Bears in Malaysia and Indonesia (Shepherd and Shepherd 2010, Krishnasamy and Shepherd 2014). Understanding consumer motivation, and educating and changing the behaviour of potential consumers of bear products, could be an incredibly effective tool. This is especially important given that law enforcement is generally underfunded and unfocused.

Increasing our scientific knowledge of Sun Bear ecology, population distribution, status and effects of threats is also needed. Aside from a now outdated global Status Survey and Conservation Action Plan for this species (Servheen et al. 1999), only one range country (India) has developed a National Conservation Action Plan for Sun Bears (Sathyakumar et al. 2012). Range mapping efforts, ongoing since 2006, have suffered from lack of presence data. But in 2014, the Bear Specialist Group mapped the current range-wide distribution of Sun Bears based on collation of more than 2000 presence points from throughout the range and with input from numerous experts. This has resulted in the most up to date range map for the species. The veracity of Probable range depicted by experts remains unclear. Habitat modelling approaches (e.g., Maxent; Nazeri et al. 2012) generate maps of potential distribution and may thereby help direct field surveys to promising locations to ascertain bear status; however such models are often generated with bear presence data from a small area and extrapolated broadly, and should thus be treated with caution. There remain large areas for which sun bear status is uncertain, most noticeably in Myanmar, where further research is needed.

Furthermore, it is important to establish the geographic distribution of Sun Bears at finer scales, taking into consideration habitat and fragmentation within and between countries, in order to better direct conservation actions and monitor habitat changes accurately (i.e., forest loss and fragmentation).

In 2006 The Bear Specialist Group mapped important habitat blocks for long-term survival of Sun Bears (Bear Conservation Units-BCUs). Anti-poaching efforts and forest boundary protection efforts within BCUs should be a high priority. Presently no BCUs receive support just for bears, but BCUs in some countries coincide with protected areas that receive substantial conservation support for other species (such as tigers), and bears benefit as a result (Steinmetz and Garshelis 2014). The possibilities to link bear conservation with that of other species should be explored and promoted more widely.

Efforts are currently underway to develop a standard methodology with which to monitor occurrence, relative abundance and trends of Asian bear populations through repeat sign transects. To this end, methodologies to distinguish Sun Bear claw marks from Asiatic Black Bear claw marks and to age claw marks have been developed (Steinmetz and Garshelis 2008, 2010). Surveys using this technique have been completed in Lao PDR and are planned for Vietnam and Cambodia. Trends in bear occurrence and relative abundance within the aforementioned BCUs should be monitored using standardized sign surveys and camera trapping by local government, communities, and NGOs. Results of such monitoring could indicate which management or ecological conditions promote successful bear conservation, and which do not, and provide a means to assess the results of conservation efforts (e.g., future range expansion and/or increased bear density being indicative of effective conservation efforts). Additional field studies would also be helpful in this regard, as few intensive studies have been conducted on Sun Bears.