Introduction

Male Mottled Duck in flight, central FL, September.

Figure 1. Year-round range of the Mottled Duck.

The Mottled Duck, a southern relative of the American Black Duck (Anas rubripes) and the Mallard (Anas platyrhynchos), inhabits peninsular Florida and coastal marshes along the Gulf of Mexico from Alabama west and south to Tampico, Mexico. Established populations also exist in South Carolina and Georgia as a result of introductions.

This is a dabbling species that prefers freshwater wetlands including marshes, natural and human-made ponds, ditches, and impoundments in both rural and suburban areas in Florida, and coastal marshes and inland freshwater wetlands along the western Gulf Coast. Although often the least gregarious of North American Anatini, large concentrations may be found in fallow-flooded agricultural fields and storm- and wastewater treatment impoundments during wing molt in Florida and in harvested rice fields after breeding along the western Gulf Coast.

Mottled Ducks are seasonally monogamous. Compared to other species of ducks, pair formation occurs early, with nearly 80% of all individuals paired by November. Breeding starts in January, continuing into July and usually peaking in March–May. Females build nests on the ground or suspended immediately above it in dense stands of grass or other vegetation. Most pair bonds probably terminate during incubation, but some may persist through brood-rearing; only females incubate eggs. Ducklings tend to hatch together over a period of about 24 hours; once hatched, the female parent leads them to nearby shallow wetlands containing emergent vegetation, where the ducklings find the invertebrate foods that sustain them during their period of rapid growth. Adults eat aquatic invertebrates as well, but also seeds (especially rice in fall), tubers, and even small fish.

Wetland drainage in Florida, degradation of coastal marshes by saltwater intrusion and erosion in Louisiana and Texas, and urban development throughout the range pose serious conservation challenges for managers of this species. In Florida, introgressive hybridization with feral Mallards (domesticated strains released into the wild) is possibly the single greatest threat to the future of the Mottled Duck as a unique species. Education of the general public about the negative impacts of releasing domestic Mallards -- with the goal of reducing new releases and care of existing feral stock -- is an urgent, on-going conservation priority.