Change in weight or general body condition. Enlargement or swelling on the body. Any bleeding or injury. Vomiting or regurgitation. 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.