Common Merganser

Mergus merganser

Order ANSERIFORMES - Family ANATIDAE - Subfamily Anatinae

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1. Cool Facts
2. Description
3. Similar Species
4. Sound
5. Range
6. Habitat
7. Food
8. Behavior
9. Reproduction
10. Conservation Status
11. Other Names

A large diving duck with a long thin bill, the Common Merganser is found along large lakes and rivers across the northern hemisphere. The long bill has toothy projections along its edges that help the duck hold onto its slippery fish prey.

Cool Facts

• The Common Merganser usually nests in tree cavities, either those made by large woodpeckers or from where a limb broke off. It will also use a nest box. Infrequently a Common Merganser might make its nest in a rock crevice, a hole in the ground, a hollow log, in an old building, or in a chimney.
• Young Common Mergansers leave their nest hole within a day or so of hatching. The mother protects the chicks, but she does not feed them. They dive to catch all of their own food. They eat mostly aquatic insects at first, but switch over to fish when they are about 12 days old.

• Gulls of various species often follow flocks of foraging Common Mergansers. The gulls wait for the ducks to come to the surface with fish, and then they try to steal their prey. Occasionally even a Bald Eagle will try to steal a fish from a successful merganser.

Description

• Size: 54-71 cm (21-28 in)
• Wingspan: 86 cm (34 in)
• Weight: 900-2160 g (31.77-76.25 ounces)

• Large, slender diving duck.
• Long, thin, orange bill.
• White patches in wing visible in flight.
• Male with bright white sides and iridescent green head.

Sex Differences

Male boldly patterned with white sides, black back, and green head. Female dull gray with reddish head and white chin.

Male

Breeding (Alternate) Plumage: Head iridescent greenish black. Neck, underparts, and sides white. Back and tail gray. Black line along sides of back. Outer part of wings black. Bill scarlet-orange.
Nonbreeding (Basic) Plumage: Head rusty brown with short, ragged crest. Chin white. Breast, back, wings, and tail slaty gray. Belly and flanks white. Bill scarlet-orange. White patch in wing visible in flight. Like female, except crest on head may be shorter and wing has larger white patch.

Female

Head rusty brown with short, ragged crest. Chin white. Breast, back, wings, and tail slaty gray. Belly and flanks white. Bill scarlet-orange. White patch in wing visible in flight.

Immature

Immature resembles adult female.

Similar Species

• Red-breasted Merganser male has shaggy crest, reddish dark chest, gray sides, and red eyes. Female is more dirty looking, with duller brown head that fades gradually into dingy breast, lacks distinct white chin, and has a longer crest.
• Male Mallard also has green head, but has a dark chest, lacks white on the body, and does not dive after fish.
• Winter loons can look similar, but generally have thicker bills, more white in the face, and lack sharply demarcated dark head.

Sound

Silent except in courtship when male makes a hoarse croaking, a twanging sound, or a bell-like note. Female makes a harsh "gruk." Wings produce a rushing noise in flight.

»listen to songs of this species

Range

Summer Range

Breeds from Alaska to Newfoundland, southward to New Jersey, Minnesota, New Mexico, and California. Also across northern Eurasia.

Winter Range

Winters from southern Canada to North Carolina, Kentucky, Arkansas, and northern Mexico, and farther north along the coasts. Also Eurasia southward to northern Africa and northern Vietnam.

Habitat

Breeds along lakes and rivers bordered by forests. Winters on large lakes, rivers, coastal bays, and estuaries.

Food

Small fish, insects, mollusks, crustaceans, worms, frogs, small mammals, birds, and plants.

Behavior

Foraging

Dives underwater to catch prey.

Reproduction

Nest Type

Nest in tree cavity or nest box, lined with downy feathers from chest of female.

Egg Description

Creamy white

Clutch Size

6-17 eggs.

Condition at Hatching

Covered with down, eyes open. Leave nest within one or two days after hatching.

Conservation Status

Populations appear stable.

Other Names

Grand Harle, Mergo mayor (French)
Goosander (English)

Sources used to construct this page:

Mallory, M. and K. Metz. 1999. Common Merganser (Mergus merganser). In The Birds of North America, No. 442 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.