Supplementary feeding of wild red-legged partridges Alectoris rufa with wheat is a widespread management practice in hunting areas in Spain. Many studies note that energetic diets affect the physiology of hand-reared galliforms. In order to assess if cereal supply might also affect wild birds, we studied the weight of the heart, spleen and liver, and the length of the small intestine and caecum of 129 wild red-legged partridges from three hunting estates where wheat is supplied, and compared it with 67 partridges from two non-supplied estates. Non-supplied partridges had heavier hearts (9%, both in juveniles and adults), and longer caeca (20% in juveniles and 14% in adults) than supplemented birds. An excessive intake of energy-rich items, such as the wheat supplied, instead of fibre-rich or proteic natural food, might explain the differences found. The management implications of these findings are discussed.