Energy is a fundamental need of all living things and dictates the daily rhythms of wild gibbons, who spend the vast majority of their waking hours searching for, processing and eating food. In human care, satisfying an animal’s energy requirement is rarely difficult. The primary challenge is establishing appropriate balance of energy intake with that of other necessary nutrients. When this balance is skewed, the consequences for the animal’s health and welfare are severe. Many diseases seen in captive gibbons can be directly attributed to inappropriate. These include obesity, type 2 diabetes, dental caries, reproductive complications, and chronic digestive issues like bloat and diarrhea. At the other end of the spectrum, inappropriate diets, especially in animals which were kept as pets, can cause poor body condition, skeletal deformities, and severe nutritional deficiencies.
Furthermore, inappropriate diets also exacerbate behavioral problems. When gibbons can consume their daily caloric needs in a few minutes from a bowl of high-sugar food, they are left with hours of unoccupied time. This frequently leads to stereotypic behaviors (like repetitive pacing or rocking), or lethargy. Therefore, a captive diet must be holistically formulated. It must take into consideration the animal’s nutritional needs, the specific feeding ecology (for example, recognising that some gibbons, like the siamang, requires more fibre-rich foliage than others), as well as their individual history to ensure that species-specific feeding patterns can be successfully carried out in a sanctuary setting. And we also need to consider how to present that diet, to ensure natural behaviours can be expressed and practiced.