Quick Answers
Mottled ducks and black ducks are two closely related species of dabbling ducks found in North America. The main differences between them are:
- Plumage – Mottled ducks have mottled brown and tan plumage, while black ducks are mostly dark brown or black.
- Range – Mottled ducks are found along the Gulf Coast and in the southwestern states, while black ducks are found in eastern North America.
- Habitat – Mottled ducks prefer freshwater marshes and ponds, while black ducks are found on fresh and saltwater habitats.
- Size – Mottled ducks are slightly smaller on average than black ducks.
- Behavior – Mottled ducks are non-migratory while black ducks are migratory.
Plumage Differences
The most noticeable difference between mottled ducks and black ducks is their plumage or feather coloring and patterning.
Mottled ducks, as their name suggests, have mottled brown and tan plumage. The body feathers are brown and tan with buff-colored edges that give the mottled appearance. The head and neck is tan with a dark brown crown. The chest is tan-brown and the belly whitish. The speculum or wing patch is iridescent green and purple bordered by black and white bars. The bill is yellowish-green and the legs and feet are yellowish.
Male and female mottled ducks have nearly identical plumage, although the male may be slightly larger. Juvenile mottled ducks have a duller, browner overall appearance than adults.
Black ducks, on the other hand, are mostly dark brown or black in color as their common name suggests. The head, neck, chest, back and wings are dark brown to black, and the speculum is iridescent violet to purple bordered by black and white. The belly is lighter brown mottled with white. The bill is olive-green to yellowish, and the legs and feet are orange-yellow.
Male and female black ducks are similar in appearance, with the female being slightly smaller. Juvenile black ducks have plumage similar to adult females.
The darker coloration of the black duck provides better camouflage in its wooded wetland habitat environment. The mottled brown plumage of the mottled duck blends in well with the marshes of the Gulf Coast region.
Plumage Changes Between Breeding and Non-breeding Seasons
The plumage of mottled ducks remains relatively consistent year-round. However, black ducks undergo a molt or feather change twice per year.
In the late summer and fall, male black ducks molt into what is called “basic plumage.” Their new feathers are more brownish-gray rather than black. The speculum becomes darker and less iridescent. This non-breeding or “basic” plumage provides better camouflage during winter months.
In spring, male black ducks molt again into their bright “alternate” or breeding plumage. The body becomes much darker black, and the speculum regains its bright purple and green iridescence. This plumage signals fitness to females and intimidates competing males during the breeding season.
Range and Habitat
Mottled ducks and black ducks have distinct ranges across North America. Mottled ducks are found predominantly along the Gulf Coast region, while black ducks are found mainly in eastern North America.
Mottled Duck Range and Habitat
The range of the mottled duck extends across the southern tier of the United States from southeastern Texas along the Gulf Coast to the Florida panhandle. A small population is also found in south-central Arizona.
Within this range, mottled ducks prefer freshwater wetland habitats such as coastal marshes, swamps, wet prairies and ponds. They are non-migratory and do not stray far from their breeding areas.
Some key facts about mottled duck habitat:
- Found in freshwater inland habitats, unlike many duck species
- Prefer shallow wetlands with dense emergent vegetation for cover
- Nest over water in marsh vegetation or on dry land nearby
- Forage on seeds and plant material from marsh vegetation
- Do not require deep waters like diving ducks
Black Duck Range and Habitat
Black ducks are found mainly in eastern North America, with their range extending across Canada and the eastern United States.
Key facts about black duck habitat:
- Found in freshwater and saltwater marshes, ponds, rivers
- Nest in concealed locations in forests near water
- Prefer shallow wetlands with dense vegetation
- In winter can be found in coastal bays, estuaries and open ocean
- Forage on aquatic plants, seeds, mollusks and insects
Unlike the non-migratory mottled duck, black ducks are migratory. They breed in northern areas of eastern North America in spring and summer. In the fall and winter, they migrate southwards and winter along the Atlantic and Gulf Coasts, mixing with mottled duck populations there. Habitat loss in eastern North America has reduced black duck breeding grounds and populations.
Size Differences
Mottled ducks are slightly smaller on average than black ducks, although their size ranges overlap broadly.
Some key size differences:
- Mottled Duck
- Length: 18-24 inches
- Wingspan: 31-37 inches
- Weight: 1.4-1.8 pounds
- Black Duck
- Length: 19-25 inches
- Wingspan: 32-39 inches
- Weight: 1.5-3 pounds
As seen above, mottled ducks on average are slightly smaller in length, wingspan and weight compared to black ducks. However, there is significant variation within both species, so size alone cannot be used to reliably distinguish between the two species.
Sexual Dimorphism
In both mottled and black ducks, the females are slightly smaller and less colorful than males on average. This is known as sexual dimorphism and is common among many duck species. However, the size difference between males and females is relatively small compared to more dimorphic species like mallards.
Behavioral Differences
Mottled and black ducks exhibit some key behavioral differences related to migration and breeding behaviors.
Migration
Mottled ducks are non-migratory, remaining year-round on their breeding grounds along the Gulf Coast. They may make small local movements in response to water availability, but do not make long seasonal migrations.
Black ducks are migratory. They breed during spring and summer across Canada and the northern United States. In fall and winter, black duck populations that bred further north migrate southwards to overwinter along the Atlantic and Gulf Coasts. Some black ducks may remain year-round on breeding grounds if conditions allow.
Breeding and Courtship
Both mottled and black ducks usually form monogamous pairs during the breeding season, although some males may mate with multiple females. Courtship displays are similar between the two species.
Some key breeding behaviors:
- Males perform courtship displays such as head-bobbing, wing-flapping, body shakes
- Pairs select nest sites together, with the female building the nest
- Nests are bowl-shaped and lined with down feathers
- Clutch size is around 8-12 eggs for both species
- The female incubates while the male remains nearby to stand guard
- Ducklings hatch after around 28 days of incubation
- Ducklings are precocial and can feed themselves shortly after hatching
Black ducks tend to nest in concealed locations in forested wetlands, while mottled ducks nest more openly in marsh vegetation. Mottled ducks in particular are vulnerable to nest flooding due to their coastal habitat.
Dietary Differences
Mottled and black ducks are both omnivorous dabbling ducks, feeding mainly by tipping headfirst to forage on food items in shallow water or at the surface. Their diets overlap significantly, although some key differences exist.
Mottled Duck Diet
Mottled ducks feed on:
- Seeds and plant materials from wetland vegetation
- Aquatic invertebrates like insects, crustaceans, mollusks
- Occasionally small fish and amphibians
They do not dive or forage in deep water, instead tipping headfirst in shallows to feed. Their broad bill is well-adapted for straining food items from water or probing in mud.
Black Duck Diet
Black ducks feed on:
- Aquatic plants and seeds
- Invertebrates including insects, snails, crustaceans
- Small fish
- Amphibians
- Acorns and other tree seeds in forests
The black duck has a more varied diet, including mollusks, fish, and plant foods from both forest and wetland habitats. Their bill can grasp and crack mollusk shells. In winter, they may forage in tidal waters for mollusks and crustaceans.
Threats and Conservation Status
Both mottled ducks and black ducks face a number of conservation threats, although the mottled duck is in better shape overall.
Mottled Duck Status
The mottled duck has an estimated population of 1 million birds and is listed as a species of Least Concern by the IUCN. Threats include:
- Habitat loss and degradation, especially of Gulf Coast wetlands
- Overharvesting by hunters in the late 1800s and early 1900s
- Climate change impacts including sea level rise and increased flooding
- Exposure to lead shot and environmental toxins
Legal protections and hunting regulations have allowed mottled duck numbers to rebound from past overharvesting. Ongoing conservation of coastal wetland habitat is critical to maintain populations.
Black Duck Status
Black duck populations have declined more steeply than mottled ducks over the past century. Key threats include:
- Wetland habitat loss and degradation in eastern North America
- Competition and hybridization with introduced mallard ducks
- Overharvesting by hunters historically
- Climate change impacts on migration patterns and breeding wetlands
The black duck is listed as a species of Least Concern, but with a decreasing population trend. Ongoing conservation efforts are aimed at protecting key breeding habitats and sustaining populations.
Conclusion
In summary, mottled ducks and black ducks exhibit several key differences in their plumage, range, habitat, size, behavior, and conservation status, despite being closely related species. Understanding these differences aids in identification and highlights the need for tailored conservation approaches to maintain both species. Careful wetland management and sustainable hunting practices remain important for the future of these iconic North American waterfowl.