A baby mallard duck's diet consists of invertebrates such as worms, gastropods and small crustaceans. The protein and fat found in these sources are vital to the growing duck. The mallard duckling's egg yolk can also be used as a food source the first three days after hatching.
Once the mallard duckling is approximately 2 weeks old, its diet becomes more similar to an adult's. Adult mallards are omnivorous and opportunistic in their feeding; they consume a wide variety of invertebrates and plants. Mallard ducks are native to temperate and subtropical parts of the Americas, Europe, Asia and North Africa. Mallards are sexually dimorphic. The male mallard is characterized by its iridescent green head and gray wings, while the female features brown, spotted feathering.