“Hard release” is the process of releasing an animal from captivity to the wild without any transition period. This may be used for animals which have only spent a very short amount of time in captivity, or which are translocated from one wild location to another. Alternatively, especially for animals which have lived in captivity for a long time, a gradual transition period can be allowed, which serves multiple purposes. A “soft release” involves placing gibbons in a temporary acclimatisation enclosure inside the forest for a period of time before fully releasing them. From a nutritional standpoint, this period allows the gibbons to safely adapt to eating the specific local diet while still receiving a guaranteed daily energy and nutrient intake.
During this time, human interactions should drastically reduce, so the gibbons start to lose association between humans and food. If gibbons learn that humans provide meals, they are highly likely to approach local villages after release, which often leads to fatal conflicts. To prevent this, food should be delivered using remote pulley systems that haul the daily diet high into the cage canopy. Staff should wear neutral clothing, remain quiet, and stay out of direct sight during feeding times.