White-handed gibbons (Hylobates lar) are highly selective frugivorous primates that spend a considerable proportion of their time and energy on searching for preferred foods. Studies that have investigated this selective food choice have found that gibbons tend to choose ripe, large, yellow fruits, with a juicy-soft flesh and thin skin. However, to the best of my knowledge no one has so far investigated if there may be a connection between the choice of fruit and the nutrients that they contain. The aim of my thesis was therefore to assess the occurrence of spontaneous food preferences in captive white-handed gibbons and to analyse whether these preferences show a relationship with nutritional content.

I assessed the food preferences of three captive gibbons by using a two-alternative choice test. The animals were presented with pairs of food items, and their choice behaviour, i.e., which of the two food items they consumed first, was recorded. In total, I tested ten types of food, and each pair of food items was presented to an animal for a total of 12 times. The foods used were apple, avocado, banana, cantaloupe melon, carrot, cucumber, fig, grape, pear and tomato.