Courtesy Kenn Kaufman
The Mottled Duck resides across most of Florida, and westward around the Gulf Coast. The bulk of the population is found in the coastal marshlands of Louisiana and Texas, and in lesser numbers as far south as Mexico's eastern coast. The species was introduced to coastal South Carolina in 1976, and is now an established resident. There are few records away from the breeding range, and none outside of the Americas.
A legend for the range map to the right can be found here.
The Mottled Duck prefers coastal marshes and wetlands with shallow, fresh water and plenty of vegetation. Coastal agricultural areas, particularly rice fields, have become increasingly important to the species. Large post-breeding concentrations can be found during the rice harvest in coastal Texas and Louisiana.
In central Florida, recent drainage of swamp land for agricultural use has opened up a new niche for the species. The Mottled Duck currently thrives on seasonally flooded agricultural fields, particularly within the Everglades Agricultural Area. Ironically, current Everglades land reforms designed to decrease agricultural use and restore the area to a more natural state are proving just as detrimental to the Mottled Duck as drainage of its natural Gulf Coast wetland habitat has been.
As with many duck species, Mottled Ducks have a varied diet. Their main food source is grass seeds, rice, and aquatic vegetation, but they also feed upon invertebrates and small fish. In fall, large concentrations of Mottled Ducks can be found foraging in freshly harvested rice fields.
Pair formation takes place as early as August, much sooner than for other ducks. This helps reduce the risk of hybridization with Mallards, which generally pair much later. Nesting takes place as early as March. The female typically chooses a nest site on the ground in a grassy area near water. Less frequently, nests are suspended in grass, up to three feet above the ground. In Florida, Mottled Ducks are apt to choose atypical nest sites on agricultural land; they have been found nesting in tomato, watermelon, and sugar cane fields, as well as along irrigation ditches. Ducklings are raised by the female. The male may be present after hatching, but plays no role in the rearing of young.
The Mottled Duck is a non-migratory species. Short seasonal movements are thought to be in response to temporary factors, such as dry seasonal wetlands or food shortages.