Arnaud-James, L. 2019. The effects of structural and feeding enrichments on captive western hoolock gibbons at the rehabilitation and release centre HURO Programme, India. Canopy 20(1), 15-18.

The aim of this study was to assess the impacts of different enrichments in various enclosures in a gibbon rehabilitation centre in the northeast of India. The results show a greater interaction with the feeding enrichments (milk cardboard bottles cut in half and slotted together; bamboo tune with a cover; bamboo tube with a hole) than with the environmental enrichment (swing). Out of the three feeding enrichments, the milk bottle was overall the enrichment most interacted with, which could be explained by the flexibility and manoeuvrability of the material: indeed, objects that can be easily moved around and destroyed have higher interaction since they provide individuals with control on their environment and sensory stimulation. The milk bottles were small, light, and easy to chew on or play with. The swing mostly sparked interest in the younger individuals who used it to hang or sit or integrated it in their locomotion patterns, while older individuals were not seen engaging with the swings. The study also looked at height and substrate use by the gibbons: overall, the gibbons at the rescue centre use behaviour-appropriate heights similar to those of wild gibbons. The presence of a bamboo platform and a hammock in two enclosures allowed the individuals to rest in high levels of the enclosures. One of the enclosures did not contain a high substrate for resting but the individuals instinctively used high levels of the bamboo substrates to rest. Additionally, all the gibbons displayed a preference for the bamboo substrates which composed the structure of the enclosures.