The Mallard duck, Anas platyrhynchos, is the most widely recognized and common waterfowl species across the Northern Hemisphere. This highly adaptable duck is classified as an omnivore, meaning its diet is varied and changes based on the season, habitat, and biological needs. This dietary flexibility allows the Mallard to thrive in diverse environments, from wetlands and estuaries to urban parks and agricultural landscapes.
Aquatic and Terrestrial Vegetation
Plant matter forms the bulk of the adult Mallard’s diet for much of the year, providing necessary carbohydrates and fiber. This consumption includes seeds, stems, and roots from both aquatic and terrestrial sources. Submerged vegetation like pondweeds, smartweeds, and various algae are regularly consumed in wetland habitats.
Mallards also forage on land, grazing on grasses and searching for fallen seeds and nuts, such as acorns. During autumn and winter, Mallards frequently venture into agricultural fields to consume waste grain left after harvest. These scavenged grains, including corn, wheat, and rice, provide a high-energy food source valuable for migration or surviving colder periods.
Protein Sources and Foraging Methods
Mallards significantly increase their intake of animal protein during specific biological periods, particularly the breeding season and during molting. Laying females shift to a protein-heavy diet to acquire the necessary amino acids and calcium required for egg production. During this time, animal matter can comprise a majority of a female’s diet.
The protein sources are primarily invertebrates found in or near the water. These include aquatic insect larvae, such as those from caddisflies and dragonflies, along with earthworms, snails, and small crustaceans. This shift provides a concentrated source of nutrients that cannot be easily stored and must be acquired as needed.
Mallards employ a characteristic feeding method known as “dabbling” to access their food. The bird tips its body forward in the water, submerging its head and neck while keeping its tail elevated above the surface. This behavior allows them to reach vegetation, seeds, and invertebrates in shallow water or just below the surface without fully diving. The bill is specially adapted with a comb-like structure called a pecten, which helps them strain water and sift out small food items.
Diet of Ducklings and Harmful Human Foods
Newly hatched Mallard ducklings have specialized nutritional requirements that differ significantly from their parents. For the first few weeks of life, their diet is dominated by small, soft-bodied invertebrates, which provide the high protein content necessary for rapid growth and feather development. The young ducks forage for themselves almost immediately but rely on their mother to guide them to areas rich in aquatic insects and other small prey.
Feeding Mallards processed human foods can be detrimental. Items like bread, crackers, and chips are high in carbohydrates and offer virtually no nutritional value to the ducks. When ducks fill up on these “junk foods,” they lose the motivation to forage for their natural, nutrient-rich diet, leading to malnutrition.
A health consequence of this poor diet, particularly in young, developing birds, is a condition called ‘angel wing’. Angel wing is a deformity where the last joint of the wing twists outward, preventing the bird from flying. The condition is linked to a nutritional imbalance, specifically a diet too high in carbohydrates and protein during a critical growth period, which causes the wing bones to grow faster than the supportive muscle and tendon structure.