Watching how a gibbon eats and acts is one of the best ways to check its mental health. In a cage, life is much easier than in the forest. Without the need work hard to survive by finding food and avoiding predators, boredom is an important risk. This often causes abnormal, repetitive behaviors, also known as stereotypic behaviours. You might see a gibbon pacing back and forth, rocking its body, pulling out its own hair. Some animals instead may show signs of apathy, just sitting quietly and ignoring everything.
Sanctuary staff should be trained to look for these warning signs daily. If a gibbon starts exhibiting these behaviors, it is a clear message that they are stressed or their environment is too boring. Understanding what triggers these behaviours is important, before we can make informed decisions how to intervene. Stereotipic behaviours develop as a coping mechanism in these animals. Therefore, simply trying to stop or prevent the animal exhibiting these behaviours might cause even more stress, and worsen the welfare of the animal.
Some animals may arrive with existing abnormal behaviours. These can be especially difficult to manage, and require staff time, skills and patience. It can be helpful to undertake some structured behavioural observations, to understand the timing, potential triggers and extent of these abnormal behaviours. This is time consuming, but nevertheless important in our attempt to manage them. Camera traps or video cameras might be very useful to monitor animals in the absence of the human caregivers’ presence, which can sometimes significantly influence the behaviour of animals.
To manage these stereotypic behaviours or apathy, we need to try to resolve the underlying issue. Sometimes these stem from anticipating when feeding or other routine activities are due to happen. Animals have a surprisingly good sense of time, when they know certain activities happen at the same point every day. Keeping the daily routine slightly unpredictable helps keep the gibbon’s brain active and reduces stress in some cases. Staff can also offer new types of puzzle feeders, making foraging more time consuming, and therefore more similar to what it would be like in the wild. Increasing the amount of browse and wild foods may also help, as these are slower to process, and generally contain high level of fibre which needs more chewing. We should consider when, how and how much food is presented, and if any of these aspects could be changed to achieve our goal: more time spent on finding, processing and eating fruit, leading to less time spent exhibiting stereotypic behaviours or being bored.