Common Merganser

Mergus merganser

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Photo of a male common merganser floating on water.
Male common mergansers have a green head, a mostly white body, and a black and gray back.
Noppadol Paothong
Family

Anatidae (ducks, geese, swans) in the order Anseriformes

Description

Common mergansers have a long, slender, serrated, red or orange bill with a wide base. Males have a green head, a mostly white body, and a black and gray back. Female has a gray body with a rusty head that is sharply defined against the white neck. Voice is a hoarse croaking car-r-r-r or rapid cackling notes. Mergansers are divers, and the legs are far back on the body; on land, the posture is upright.

Similar species both have larger crests: Red-breasted merganser males have gray sides, a dark chest and back, and a ragged crest; females have a pale rusty head with an indistinct border between rusty head and gray-white breast. Hooded merganser males have black and white head, crest, and back, with chestnut flanks; females are brown with rusty crest.

Size

Length: 25 inches (tip of bill to tip of tail).

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Photo of a female common merganser floating on water.
Common Merganser Female
The female common merganser has a gray body with a rusty head that is sharply defined against the white neck.

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Photo of a male common merganser floating on water, eating a fish.
Common Merganser Eating Fish
Common mergansers eat fish, frogs, and aquatic invertebrates. The serrated bill helps them grab slippery fish.

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Photo of a female common merganser, closeup on head and front.
Common Merganser

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Photo of two male common mergansers flying low over water.
Common Mergansers in Flight
Common merganser breed mostly in Canada. In Missouri, we most often see them in spring, fall, and winter.

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Photo of two female common mergansers standing and sitting on pond ice.
Common Mergansers (Female)
Common mergansers are divers, and the legs are far back on the body; on land, the posture is upright.
Habitat and conservation

Common migrant and winter resident on rivers and lakes, foraging in deep water. This species is also native to Eurasia, where it is commonly called the “goosander.” Our North American common mergansers are a separate subspecies, Mergus merganser americanus.

Foods

Forages on rivers and lakes for fish, frogs, and aquatic invertebrates. Mergansers hunt their prey by sight and dive completely underwater to snag their prey. They are heavy bodied and small winged, designed for diving below the water and pursuing fish by swimming with their powerful webbed feet. The serrated bill helps them grab slippery fish.

image of Common Merganser distribution map
Distribution in Missouri

Statewide.

Status

Common transient and winter resident (uncommon in southeast); accidental summer visitor.

Life cycle

The breeding territory of common mergansers lies mainly in Canada. They usually nest in cavities in dead trees, sometimes using abandoned woodpecker nests, and also use specially made nest boxes. Clutches contain 6-17 eggs. The young jump from the nest hole within a few days of hatching and are able to forage for their own food — with their mother’s protection.

Human connections

In some places where it occurs, humans persecute the common merganser as a competitor for game fish. Duck hunters rarely harvest this bird, since its meat has been described as “so rank and strong” the flavor is “not much superior to that of an old kerosene lamp-wick.”

Ecosystem connections

The common merganser, being a species of forest and water habitats, relies on the health of both. Successful nesting requires mature forests complete with dead cavity trees, and successful foraging requires waters that are not overburdened by sediment.