Mottled Ducks of Florida
Hybridization threatens this species in Florida
Mottled ducks ( Anas fulvigula) are residents of Florida and coastal marshes of the Gulf of Mexico. More than half the mottled duck population in Florida is in Lee, Charlotte, Hendry and Glades counties. They are also abundant in the St. Johns River marshes and Merritt Island National Wildlife Refuge in Brevard County.
Many mottled ducks observed today, however, are most likely hybrids, resulting from cross-breeding with the semidomesticated mallard ducks that occupy the same breeding habitats. Because of this hybridization the pure mottled duck species may eventually disappear from Florida.
This species is divided into two subspecies. The eastern subspecies, which resides on the coast from Florida through South Carolina, is A. fulvigula fulvigula, and the western subspecies, ranging from northeastern Mexico to Louisiana, is A. f. maculosa.
The mottled duck’s structure is similar to Florida mallards, the most recognized duck species in Florida, though mottled ducks are smaller with shorter wings. The male and female mottled ducks are similar in appearance, but with careful observation the sexes can be distinguished.
The mottled duck adult female has a dark brown chunky body with golden brown, V-shaped marks on the interior of the flank feathers. It has an unmarked throat and buffy brown face with a slightly darker crown and eye line. The uniquely colored secondaries of its wings are known as the speculum and are blue-green with black and very narrow white borders. The bill is an olive-yellow or dull orange, flecked black on the top of the bill, or culmen. The adult male mottled duck looks like the female but with a yellow bill and a black spot at the gape of the bill.
The female mallard is lighter brown than the mottled duck. It also has an orange bill with a black saddle on the culmen. The male mallard is more recognizable with its metallic green head, white ring, curled tail feathers, chestnut breast and yellow bill. The semi-domesticated mallard does not have the white collar. In both mallard sexes the speculum is metallic blue, bordered back and front with a white stripe. Florida mallards do not have the black spot at the gape of the bill that is present in mottled ducks.
Mottled ducks are different from mallards in that they keep their pair bond for most of the year and are usually observed in pairs rather than large flocks. They are year-round residents of Florida except for the Florida Keys. They breed in Florida from February through September. True mallards are common winter visitors from late September to early March but do not breed in Florida. The Florida mallard semi-domesticated stock, however, does breed in Florida and is mostly seen with mottled ducks on freshwater and
brackish marshes, lakes, ponds, streams and flooded agriculture fields. Some breed in the wild.
Nesting occurs predominantly between early March and midApril but can extend into September. Nests are usually located near water, but mottled ducks will also nest far from water. Their nests are often found in the drier parts of a wetland or on a sandy ridge, and are placed in aquatic vegetation, reeds, matted grass and rushes or in the cover of sheltering vegetation. Mottled ducks occasionally nest in tomato and other agricultural fields.
The mottled duck usually lays 8-10 eggs, with a range of 5-13 eggs, in a ground nest lined with breast and down feathers. The eggs are creamy white to greenish-white in color and are just over 2 inches in size. The female incubates the eggs for 25-27 days. The young are precocial in that when they hatch they are mobile, downy and follow their parents to find their own food. They fledge in 60-70 days. Mottled ducks produce only one brood per year.
The ducks will desert their nests if disturbed by humans or predators. Young scatter and hide in vegetation on a female’s alarm. This alarm attracts the male, which circles overhead and calls but does not approach.
Mottled ducks are dabblers as they tilt forward to forage mostly on aquatic vegetation and animals just below the water’s surface. A variety of animals make up one-third of their diet in the summer, which includes aquatic vegetation, berries, grass, seeds, grain, insects, crustaceans, fish, mollusks and snails.
These ducks add to the biodiversity of the environment. They are both predators and prey in the food chain. They are enjoyed by hikers, campers, tourists, birders and hunters. They are an important game species in Florida.