Mottled ducks are a medium-sized dabbling duck that are intermediate in appearance between a female mallard and an American black duck. The male mottled ducks is easy to distinguish because it lacks the mallard drake’s bright green iridescent head. Distinguishing a mottled duck from a female mallard can be more difficult, though. The neck and head of a mottled duck is lighter colored than its body feathers, whereas the female mallard does not have this color pattern. Also, the female mallard has a broad, white wing bar above and below the colored portion of her wing (called the speculum). The female mottled duck lacks the upper wing bar but may have a faint lower bar.
Because the plumage of male and female mottled ducks is similar, the easiest way to tell them apart is by bill color. The male mottled duck has an olive green to yellow bill whereas the female has an orange to brown bill with dark blotches or dots. These dots are most prevalent on the underside of the female's bill.
The Florida mottled duck, often called the Florida duck or Florida mallard, is a unique subspecies found only in peninsular Florida. This nonmigratory duck spends its entire life within the state’s brackish and freshwater marshes, ponds, lakes, rivers, canals, ditches, and mosquito impoundments on the east and west coasts and inland. Approximately 40 percent of the mottled duck's diet consists of insects, snails, mollusks, crayfish and small fish. The remainder of its diet is composed of grass seeds, stems, and roots; seeds of other marsh plants; and bayberries.
Florida mottled ducks nest from February through July. The females tend to locate their nests in dense vegetation (tall grasses, rushes or palmetto thickets) on the ground near water. The nest is built of vegetation and lined with down. Only one brood each year is raised and females typically lay 8 to 10 eggs called a clutch. The eggs are creamy-white to greenish-white and are incubated within 25 to 27 days.
Unlike such birds as the mockingbird or blue jay, which raise their young in the nest for weeks, mottled duck females will move their ducklings to water within 24 to 48 hours of hatching. Young mottled ducks are capable of flight at 60 to 70 days of age.
The mottled duck belongs to a worldwide group of approximately 20 species of closely related ducks called the mallard complex. All the species in this complex have a similar body shape but their feather characteristics and color distinguish them from one another.
The Florida mottled duck is one of a few non-migratory ducks in North America. Therefore, the management and protection of this subspecies is primarily the responsibility of the Florida Fish and Wildlife Conservation Commission (FWC). The long-term well-being of Florida mottled ducks is threatened by crossbreeding with feral, domesticated mallards and the FWC is working hard to combat this problem.
Feral mallards are mating with mottled ducks, producing a hybrid offspring. State biologists are observing more mixed flocks and mixed pairs in the wild. These hybrid offspring are fertile, which further compounds the problem. Every mallard released in Florida can potentially contribute to the hybridization problem and the result is that fewer pure-bred Florida mottled ducks are left each year. The complete hybridization could result in the extinction of the Florida mottled duck, which is a defining member of the unique suite of species characteristic of south Florida’s prairie ecosystem.
In addition, rapid changes in the landscape of south Florida, attributed mostly to agricultural and urban development, have raised concerns about the status of these wetland habitats and the wildlife that depend on them.
It will take an effort by not only the FWC, but all Floridians, to ensure the continued existence of the Florida mottled duck.