Ducks, geese, and swans · Waterfowl
Common Merganser
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Mergus merganser
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Voice
Song
How to recognize it
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About the size of a small goose
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Adult male in breeding plumage: black-green head, white body with a pink tinge
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Females and males in eclipse (July–October): mostly grey, reddish-brown head, white throat
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Hooked bill tip: bright red in adult males, duller in juveniles
About the species
In breeding plumage, the male has a dark green-black head above a mostly white body, sometimes washed pink, with a gray tail and a broad white patch on the inner wing. The female is gray above and pale below, with a warm reddish-brown head and neck, white throat, and a sharp brown-to-white boundary on the neck. Both have a long, narrow bill with a hooked tip; the female’s colors are also seen on males outside breeding season.
They swim low in the water and dive for prey, sometimes working together in a semicircle to drive fish into shallows. Wary on the river, they may rest on midstream rocks with wings half-open. The usual call is a low, harsh croak; males and young give a soft, plaintive whistle during breeding season.
They use forested rivers and lakes, nesting in tree cavities near water. They eat mostly fish, gripping slippery prey with tooth-edged bills, and some stay where water remains open through winter while others move south when lakes and rivers freeze.
Where to find
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During the breeding season, on the wooded shore of a freshwater lake or reservoir, look in the tree shade for a Common Merganser diving for fish.
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On small, fast-flowing rivers, pairs and small groups twist around in rapids; in deep pools below a waterfall or rapid, they fish vigorously.
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On rocks mid-river, look for resting with wings half open in the sun.
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In winter, on an ice-free stretch of a large river—wintering records include the Dnieper near Kyiv—watch for resting at the edge of floating ice.
