Detailed information about the range and composition of the diets of free-ranging wild animals is extremely limited. The nutritional protocols of wildlife-conservation programmes or the maintenance of wild animals in captivity are based on a limited understanding of species’interactions and habitat strategies. More detailed information on diet can be obtained from direct observations of feeding, analysis of leftover food around feeding or nest/den sites, or identification of components in the digesta at various stages through the digestive tract, including faeces or pellets. In order to gather more specific data from animals it is essential that the food that has been consumed can be identified, even if it only appears as fragments within the digesta, faeces or pellets. The amounts eaten and how various foods respond to the rigours of digestion are also important; for example, soft prey items may be under-represented or non-existent at the end of the digestion process. This article describes various methods that can be used to identify the food items consumed by animals and suggests studies that can be carried out in both the wild and captivity to facilitate the development of a detailed and species-specific reference bank of food items.