Context. The lack of documentation and detailed assessment of previous sun bear (Helarctos malayanus) release programs raises concerns about bears’ capacity to adapt to their new habitats and key elements of release success.
AimsWe evaluated the influence of the sun bears’ individual profiles and environmental factors on their adaptability, and investigated their habitat use and movements in the wild.
Methods. We released 13 rescued sun bears (four wild-caught and nine rehabilitated) to natural habitats between December 2015 and August 2017, and inferred adaptability process by analysing their pre- and post-release data.
Key results. Post-release monitoring showed that sun bears required at least a month to acclimatise to their release area. No nuisance cases were reported, and bears were observed avoiding monitoring teams in a series of encounters. Principal-component analysis identified a previous history of ill health (e.g. malnutrition), low avoidance of humans prior to release and low potential of release sites as significant factors associated with poor adaptability of released bears. Rehabilitated bears also showed lower adaptability to hilly topography with an average elevation of more than 500 m. Individual profiles of adult physically fit wild-caught bears with high avoidance of humans prior to release were associated with high adaptability. Binary logistic regression indicated that habitat type was the main factor influencing bear movement. Bears had a high affinity for oil palm plantations adjacent to the forest edge. Most habitat use of released bears was close to the forest edge.
Conclusions. In terms of competition, predation, food availability, and adaptability, the selection of forest edges adjacent to other favourable habitats is perceived as a more opportunistic survival strategy, as long as the bears do not rely on humans to survive and endure with the natural interactions in the wild.
Implications. This study emphasises the importance of improving the likelihood of survival of rehabilitated bears, especially in the early release phase. Reducing human–bear interaction in rehabilitation centres by practising a buddy system and minimal human contact in captivity considerably enhances release effectiveness.