All swans are grazing birds. They eat both aquatic and land vegetation. Rye grass, alfalfa, corn and maybe even clover if it is the right kind will serve as a vegetative food resource for swans. Any grasses or flowering plants, such as petunias, choleus, etc., that rabbits, deer, cows or other grazing animals eat will usually serve the same nutritional needs for swans. The Regal Swan