Discharge from nostrils, eyes or mouth. Birds starve on poor diets. Birds starve on diets lacking sufficient minerals - all seed diets are deficient in calcium and other minerals. Birds starve on diets low in protein - millet seed is common example of a seed low in protein and deficient in amino acids. Diets high in fruit and greens cause the same problem.
Birds starve on diets lacking sufficient vitamins - seeds are deficient in many vitamins.
Birds starve on diets low in carbohydrates - lettuce, spinach, endive and other greens have little nutritional value. Birds starve on old food. Birds starve if fed cafeteria style - allowed to pick their own diet from a variety of food. Birds starve when people don't care. Budgerigars are small, colorful birds with gregarious, entertaining personalities.