The mallard (Anas platyrhynchos) is one of the most recognizable and widely distributed waterfowl species across the Northern Hemisphere. As a dabbling duck, it is highly adaptable, inhabiting nearly any freshwater environment from wild wetlands to urban parks. The majority of mallard populations are migratory, moving seasonally between distant locations. This movement is a direct response to the availability of open water and food resources, which are limited by the freezing temperatures of northern winters.
Defining the Northern Breeding Grounds
The primary geographical areas where mallards concentrate to breed during the spring and summer are in the northern United States and Canada. The highest concentrations of nesting mallards are found within the Prairie Pothole Region, which spans from the north-central U.S. states like the Dakotas and Montana into the Canadian provinces of Manitoba, Saskatchewan, and Alberta. This region is often called the “duck factory” of North America due to its abundance of small, glacier-formed wetlands that offer ideal nesting habitat and a rich supply of invertebrate food sources for raising ducklings.
Mallards also breed extensively across the western Canadian Boreal Forest and in the tundra and river deltas of Alaska. These northern areas provide the necessary dense upland vegetation for females to build their nests, which are typically shallow bowls on the ground, lined with down feathers. The female often exhibits philopatry, returning to nest in the general area where she was hatched or previously nested successfully.
Primary Wintering Destinations
When northern wetlands freeze, mallards migrate south to warmer climates where water remains open and food is accessible, often traveling as far as northern Mexico. The most significant wintering destination is the lower Mississippi River Valley, particularly the Mississippi Alluvial Plain stretching from Missouri and Illinois down to Louisiana. The complex of wetlands in eastern Arkansas, including the Cache River, Bayou DeView, and lower White River areas, is considered one of the most important wintering areas in North America, hosting up to 40% of the continental wintering population.
Another major destination is the Gulf Coast, encompassing the coastal marshes and rice fields of Louisiana and Texas, which provide abundant waste grain. In the western U.S., the Central Valley of California serves as a primary wintering habitat, especially for mallards breeding in Alaska and the Pacific Northwest. This extensive area of managed wetlands and flooded agricultural fields supports a significant portion of the Pacific Flyway’s migrating waterfowl. These areas offer milder temperatures and a reliable supply of high-carbohydrate food like waste corn and rice, necessary for maintaining energy reserves throughout the winter.
The Four Major North American Flyways
Mallards navigate between their northern breeding grounds and southern wintering destinations by following established migratory corridors known as flyways. These are not narrow, precisely defined routes but rather broad, traditional pathways that waterfowl follow, often guided by major geographical features like river systems, mountain ranges, and coastlines. North America is administratively divided into four such flyways, all of which are utilized by mallard populations depending on their starting point.
The Atlantic Flyway traces the eastern coast of the continent, channeling birds from eastern Canada and the northeastern U.S. down toward the mid-Atlantic and Gulf Coast states. The Mississippi Flyway follows the massive Mississippi River system, serving as a funnel for birds migrating from the central breeding grounds in the Prairie Pothole Region toward the most concentrated wintering areas in the lower Mississippi Valley.
Further west, the Central Flyway extends from the Canadian tundra through the Great Plains down to the Gulf of Mexico. The Pacific Flyway runs along the western edge of the continent, guiding mallards from Alaska and western Canada down the coast to wintering sites in Washington, Oregon, and California’s Central Valley. Mallards utilize all four flyways, demonstrating their widespread distribution and reliance on these corridors for seasonal journeys.
When Mallards Stay Put
While the majority of mallards migrate, some populations are considered sedentary, choosing to remain in a location year-round. Migration is triggered by the need to find open water and food; if these resources are consistently available, the ducks have no reason to travel long distances. This phenomenon is most common in regions with mild climates, such as parts of the Pacific Northwest, the southern U.S., and coastal areas.
Sedentary mallards are also frequently observed in urban and suburban environments, such as city parks and ponds, where artificial conditions negate the need for migration. They benefit from year-round open water, often maintained by human activity, and readily available food, sometimes supplied by people. These populations, especially in the eastern U.S., can sometimes interbreed with domestic or game-farm mallards, which can introduce genetic material that may affect the migratory instincts of the local wild stock.