The Mottled Duck (Anas fulvigula) is a species of waterfowl native to the Gulf Coast region of North America. As a “dabbling duck,” it feeds primarily at the water’s surface or by tipping its body, rather than fully submerging like diving ducks. This species is unique among North American ducks because it is largely non-migratory, remaining in its limited range throughout the year. Its sedentary nature and restricted distribution make it a subject of interest for wildlife biologists and conservationists.
Physical Identification and Key Features
Mottled Ducks are medium-sized ducks, generally appearing dark brown or mottled due to the buff-colored edges on their feathers. This drab coloration makes them easily confused with female Mallards or American Black Ducks. A helpful field mark is their head and neck, which are noticeably lighter, often tan or buffy, than the rest of their body.
Unlike many other duck species, the difference between male and female Mottled Ducks is subtle in their plumage. The most reliable way to distinguish the sexes is by bill color: males have a plain, bright yellow or olive bill, while females possess an orange or olive bill that often features dark blotches or spots. Both sexes also have bright orange legs and feet.
The most definitive identification feature is the speculum. On the Mottled Duck, this patch is a glossy blue-green and is bordered by a black leading edge. Critically, the speculum typically lacks the prominent white borders characteristic of the similar-looking Mallard. In flight, the silvery-white wing linings provide a strong contrast against the dark body.
Geographic Range and Preferred Habitat
The Mottled Duck is geographically restricted to two populations in North America. The Western Gulf Coast population spans the coast from Veracruz, Mexico, eastward through Texas and Louisiana, reaching Mobile Bay, Alabama. The second distinct population is found in peninsular Florida, where it is often referred to as the Florida Mottled Duck.
As year-round residents, these ducks do not undertake seasonal migrations common to most North American waterfowl. This sedentary behavior is unique among dabbling ducks in the contiguous United States. Their habitat preference is specific, centered on coastal marshes, estuaries, and brackish ponds.
The ducks also readily utilize human-altered landscapes, such as flooded pastures and agricultural wetlands. In the western portion of their range, they frequently use rice and crawfish production fields for feeding and nesting. Their reliance on these coastal and shallow-water habitats makes them particularly vulnerable to environmental changes.
Diet, Foraging, and Reproduction
Mottled Ducks are omnivorous, with their diet shifting between plant matter and animal prey depending on the season. They primarily consume the seeds and shoots of aquatic plants, grasses, and cultivated rice, especially during the fall and winter. Invertebrates form a significant portion of their diet, particularly for breeding females and young ducklings.
Their feeding style involves skimming items from the water surface or tipping their bodies head-down to reach food in shallow water. They are seasonally monogamous, with pair-bonding beginning relatively early, often in the late autumn. Nesting typically occurs between March and July, a longer season than that of many migratory species.
The female selects a nest site on the ground, usually in dense cover near water, such as thick grasses or palmetto thickets. The nest is a bowl-shaped depression constructed of plant material and lined with down. Females typically lay a clutch of 8 to 12 eggs, which are incubated for an average of 26 days. The ducklings are precocial, able to leave the nest and feed themselves within a day or two of hatching.
Conservation Status and Threats
The Mottled Duck is classified as a species of concern, with population surveys indicating a long-term decline in the Western Gulf Coast region. The two most significant threats are habitat loss and genetic hybridization. Coastal development, urbanization, and marsh degradation due to erosion and saltwater intrusion reduce their specialized wetland habitat.
Hybridization with the Mallard (Anas platyrhynchos) is a threat, particularly in Florida. Domesticated Mallards, often illegally released into the wild, breed with native Mottled Ducks, producing fertile hybrid offspring. This interbreeding compromises the genetic integrity of the pure Mottled Duck population.
Management efforts focus on habitat restoration and protection, along with regulating the release of feral Mallards to minimize genetic swamping. The encroachment of invasive species, such as Chinese tallow, also degrades nesting areas.