Ducks are a diverse family of waterfowl found in wetlands, rivers, and oceans across the globe. Their association with water often leads to curiosity about their ability to fly, especially since many species appear heavy-bodied. The vast majority of wild duck species are highly capable and powerful fliers that rely on aerial movement for survival and seasonal travel. Understanding the mechanics of this flight and why some ducks cannot fly reveals much about their biology and adaptation.
The Capability of Wild Ducks
Most wild ducks are strong, enduring flyers whose aerial skills are essential for survival. Flight is primarily used for two purposes: long-distance migration and rapid evasion of predators. These birds follow major north-south flyways, undertaking journeys that can span thousands of miles to find suitable breeding and wintering grounds.
During migration, ducks maintain impressive cruising speeds, with many species averaging around 50 miles per hour. The fastest recorded duck, a red-breasted merganser, was clocked at 100 miles per hour. While they typically fly at altitudes ranging from 200 to 4,000 feet, certain migratory species can reach much greater heights. A mallard was once documented at an altitude of 21,000 feet, demonstrating their physiological capability.
The Mechanics of Aerial Movement
The power required for a duck’s flight is concentrated in its chest, where the flight muscles are anchored to the breastbone, or keel. The two primary flight muscles, the pectoralis and the supracoracoideus, move the wings. The large pectoralis muscle powers the downstroke, generating the majority of the thrust and lift necessary for flight.
The smaller supracoracoideus muscle is responsible for the upstroke, utilizing a specialized tendon that acts like a pulley, running through the shoulder and attaching to the top of the wing bone. This mechanism allows both the upstroke and downstroke power to originate from the chest muscles. In a mallard, these flight muscles can account for approximately seven percent of the bird’s total body mass.
Ducks possess short, pointed wings classified as high-speed wings, an adaptation for continuous, rapid flapping. Their ratio of body weight to wing area, known as wing loading, is relatively high compared to gliding birds. This high wing loading demands extremely fast wing beats to generate sufficient lift, requiring ducks to flap rapidly and constantly to stay airborne. Taking off from the water often requires a laborious run across the surface to build the necessary air speed.
Reasons Certain Ducks Remain Grounded
Not all ducks can fly, and the reasons fall into two categories. The first is domestication, where selective breeding has drastically altered the duck’s physique. Breeds such as the Pekin duck have been bred for rapid growth and meat production, resulting in a body mass too great for their wing structure to support.
These domestic ducks often have smaller wings relative to their size and lack the muscle development necessary for sustained flight. Commercially raised Pekin ducks often reach full adult weight in as little as seven weeks, a growth rate that outpaces the development of functional flight anatomy. Consequently, these birds are essentially flightless, typically only managing to lift a few feet off the ground or water.
The second reason for grounded ducks is a temporary but recurring phase in wild populations known as simultaneous molting. Most wild waterfowl shed all their flight feathers—primaries and secondaries—at the same time, unlike many other birds that replace them one by one. This process renders the duck completely flightless for several weeks, typically occurring during the summer months after the breeding season. During this vulnerable time, which can last up to 45 days, the ducks rely on dense cover and water for protection while their new feathers grow in.