Ducks are adaptable birds found in various aquatic environments. While many people associate ducks with a diet of plants and insects, some duck species do eat fish. The extent to which fish comprise their diet depends heavily on the duck species, its physical adaptations, and the availability of food in its habitat. Ducks are generally omnivorous, meaning their diet can consist of both plant and animal matter.
Ducks That Eat Fish
Not all ducks are fish-eaters, but several species, particularly diving ducks, regularly consume fish as a significant part of their diet. The Merganser family is especially known for its piscivorous habits, including the Common Merganser, Red-breasted Merganser, and Hooded Merganser. Common Mergansers, often found on freshwater lakes and rivers, primarily eat fish, sometimes swallowing fish over a foot long. Red-breasted Mergansers also predominantly eat small fish, typically between 4 to 6 inches in length, and are frequently found in coastal bays and estuaries. Hooded Mergansers, the smallest North American merganser, also consume small fish, along with crustaceans and aquatic insects, inhabiting wooded wetlands and clear water bodies.
Beyond mergansers, other diving ducks, such as Goldeneyes and Scaup, may also include fish in their diet, although typically in smaller quantities. Common Goldeneyes forage underwater for aquatic invertebrates, but also eat small fish and fish eggs. Scaup species, like the Lesser Scaup and Greater Scaup, primarily feed on mollusks, crustaceans, and aquatic insects, but will opportunistically eat small fish when available.
Hunting Methods for Fish
Ducks that eat fish employ specialized hunting techniques and possess specific physical adaptations that enable them to capture slippery prey underwater. Diving ducks, such as mergansers, are adept at pursuit diving, propelling themselves with their powerful webbed feet to chase fish beneath the surface. Their streamlined bodies reduce drag, allowing them to move with agility through the water. Mergansers are often called “sawbills” because their long, slender bills are equipped with serrated edges, which help them firmly grip and hold onto fish after capture.
These specialized ducks rely heavily on their vision to locate prey underwater. Their eyes are adapted for keen underwater sight, with some species, like the Hooded Merganser, capable of changing the shape of their eyes to correct for light refraction, ensuring accurate vision both below and above the water. Some merganser species have also been observed hunting cooperatively, forming a semicircle to drive schools of small fish into shallow waters where they are easier to catch. While diving for food, these ducks typically stay submerged for less than 30 seconds, though they can remain underwater for up to two minutes.
Role of Fish in a Duck’s Diet
For specialized fish-eating ducks like mergansers, fish constitute a major component of their diet, often making up over 75% for Red-breasted Mergansers. However, for many other duck species, fish consumption is often opportunistic or supplemental to their primary diet. Fish may become a more frequent food source during certain seasons, such as fall and winter when other food sources might be scarcer. While small fish and fish eggs can be part of their diet, larger fish are typically too difficult for most ducks to catch and consume. For many duck species, aquatic invertebrates and plant matter remain the primary food sources, with fish being a less common, though still utilized, dietary item.