Gadwall

About

The Gadwall (Mareca strepera) is a medium-sized dabbling duck, known for its subtle but distinctive plumage. It is less colorful than many other dabbling ducks, often appearing grayish-brown, but close observation reveals intricate vermiculations and a prominent white speculum, especially noticeable in flight. It is a widespread species, breeding across temperate regions of the Northern Hemisphere and migrating to warmer climes for winter.

Size & lifespan

Length

46-56 cm (18-22 in)

Wingspan

78-90 cm (31-35 in)

Weight

700-1300 g (1.5-2.9 lbs)

Lifespan

Typically 5-10 years in the wild, with records up to 20 years.

Diet

Herbivore, primarily consuming aquatic vegetation, seeds, and some invertebrates.

Physical characteristics

Plumage

Males in breeding plumage are predominantly gray with fine vermiculations, a black rear end, and a chestnut patch on the forewing, followed by a striking white speculum. Females are mottled brown, similar to a female Mallard, but with a more slender neck, a smaller head, and a prominent white speculum. Both sexes have a white belly.

Beak shape

Slightly flattened, dark gray to black bill in males, often with an orange tinge on the sides in females, especially at the base.

Eye color

Dark brown.

Leg color

Dull orange to yellowish-orange.

Distinguishing features

The most distinctive feature for both sexes is the large white speculum on the secondary flight feathers, visible in flight and often at rest. Males also show a black rump and a chestnut patch on the upperwing coverts.

Juvenile appearance

Juveniles resemble adult females but are generally duller, with less distinct markings and often a more mottled appearance. The white speculum is present but may be less prominent.

Seasonal changes

Males undergo an eclipse plumage in late summer/early autumn, resembling females but often retaining some darker markings and the white speculum. They regain their breeding plumage by late autumn/early winter.

Sexual dimorphism

Pronounced. Males are grayer with a black rump and chestnut/white wing patches. Females are mottled brown with a white speculum, resembling a female Mallard but with key differences.

How to identify

1. 1

   White Speculum

   This is the most crucial field mark for both sexes. Look for a prominent white patch on the trailing edge of the wing, visible both in flight and often when the bird is resting with wings folded.

2. 2

   Male Plumage

   Observe the overall gray body with fine vermiculations, a black rump, and a chestnut patch on the upperwing coverts (just in front of the white speculum). The bill is dark gray to black.

3. 3

   Female Plumage

   Look for a mottled brown body, similar to a female Mallard, but note the more slender neck and smaller head. The white speculum is still key. The bill is often dark with an orange tinge, especially at the base.

4. 4

   Behavior

   Gadwalls are dabbling ducks, feeding by tipping up in shallow water. They are less prone to 'head-bobbing' than some other dabblers. Watch for their direct, strong flight.

5. 5

   Vocalization

   Listen for the male's low 'kreh-kreh' or whistle, and the female's softer, higher-pitched 'quack' or 'ga-ga-ga', distinct from the louder Mallard quack.

Habitat & range

Biomes

Wetlands, marshes, shallow lakes, slow-moving rivers, and estuaries.

Geographic range

Breeds across temperate North America, Europe, and Asia. Winters in southern North America, Central America, northern Africa, southern Europe, and southern Asia.

Elevation range

Primarily lowlands, up to approximately 1,000 meters (3,300 feet) in some areas.

Preferred environments

Prefers shallow, freshwater wetlands with abundant emergent and submerged vegetation, often with muddy bottoms. Less common in highly acidic or saline waters.

Behavior

Activity time

Diurnal, primarily feeding during daylight hours, though some nocturnal feeding may occur.

Feeding habits

Primarily a dabbling duck, feeding by tipping head-down to reach submerged vegetation and seeds. Also grazes on emergent vegetation and occasionally filters invertebrates from the water surface. They are known to steal food from diving ducks.

Social behavior

Often found in pairs during the breeding season, but forms larger flocks during migration and in winter. Can associate with other dabbling duck species.

Flight pattern

Strong, direct flight with rapid wingbeats. The white speculum is very conspicuous in flight. They take off directly from the water without a running start.

Migration pattern

Migratory across much of its range. Northern populations move south for winter, while southern populations may be resident or undertake shorter movements. Migration occurs in broad fronts, often at night.

Territoriality

Males defend a small territory around the female during the breeding season, but are not strongly territorial over nesting sites.

Breeding & reproduction

Breeding season

Typically April to July, varying geographically.

Nesting habits

Nests are usually built on dry ground, often concealed in dense vegetation near water. The nest is a shallow depression lined with grass, leaves, and down plucked from the female's breast.

Clutch size

Typically 7-12 eggs.

Egg description

8-12 eggs, creamy white to pale buff, unspotted. Approximately 54 x 38 mm.

Incubation period

24-27 days, incubated solely by the female.

Fledging period

Ducklings are precocial and leave the nest shortly after hatching. They are capable of flight at 45-50 days.

Parental care

Only the female cares for the ducklings, leading them to water and foraging areas, and protecting them from predators.

Where to find

Field tips

1. Look for the White Speculum. This is the most reliable field mark. Even at a distance, the white patch on the wing can help distinguish it from other ducks, especially in flight.
2. Observe Feeding Behavior. Gadwalls are dabblers. Watch for ducks tipping up in shallow water, exposing their rear ends, as they forage for submerged vegetation.
3. Study Female Plumage Carefully. Distinguishing female Gadwalls from female Mallards requires attention to subtle differences in head shape, bill color, and the crucial white speculum.
4. Listen for Calls. Their calls are generally quieter than Mallards. Learning the male's whistle and the female's softer quack can aid identification, especially in dense cover.
5. Check for Black Rump (Males). In breeding males, the contrasting black rump is a good identifier, especially when the bird is preening or in flight.

Similar species

Quick facts

Diet:

Primarily aquatic vegetation and seeds

Key ID Feature:

White speculum on wing

Habitat:

Shallow freshwater wetlands

Migration:

Migratory across much of its range

Conservation Status:

Least Concern

Fun facts

• Gadwalls are one of the few dabbling ducks where both sexes possess a white speculum, making it a key identification feature for both.
• They are known to 'kleptoparasitize' other diving ducks, stealing food that the divers bring to the surface.
• The name 'Gadwall' is thought to derive from an old English word 'gaddel' meaning 'to wander' or 'to gad about', referring to its migratory habits.
• Despite their subtle coloration, the intricate vermiculations on the male's plumage are considered quite beautiful upon close inspection.

Scientific classification

Kingdom

Animalia

Phylum

Chordata

Class

Aves

Order

Anseriformes

Family

Anatidae

Genus

Mareca

Species

Mareca strepera

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