Common Merganser

Media Player Error
Update your browser

Ducks

Common MerganserMergus merganser

ORDER: Anseriformes
FAMILY: Anatidae

Basic Description

Common Mergansers are streamlined ducks that float gracefully down small rivers or shallow shorelines. The males are striking with clean white bodies, dark green heads, and a slender, serrated red bill. The elegant gray-bodied females have rich, cinnamon heads with a short crest. In summer, look for them leading ducklings from eddy to eddy along streams or standing on a flat rock in the middle of the current. These large ducks nest in hollow trees; in winter they form flocks on larger bodies of water.

More ID Info

Year-roundBreedingMigrationNonbreeding

Range map provided by Birds of the World

Explore Maps

Find This Bird

Common Mergansers are numerous in summer along rivers in northern North America, and many a canoe trip will turn them up without much trouble. Look for them sitting on rocks in midstream, disappearing around the next bend, or flying along the river, when their white wing patches and heavy bodies make them easy to identify. In winter, seek Common Mergansers on large rivers and lakes; look for them in large flocks mixed with other ducks such as Common Goldeneye and Bufflehead. Look for the sharp dark-and-white contrast of the snazzy males and the crisply defined, rusty heads of females.

Other Names

Serreta Grande (Spanish)
Grand Harle (French)

Backyard Tips

In northern forests Common Mergansers will take up residence in nest boxes near lakes or rivers, as long as the boxes are large with a large opening. Consider putting up a nest box to attract a breeding pair. Make sure you put it up well before breeding season. Attach a guard to keep predators from raiding eggs and young. Find out more about nest boxes on our Attract Birds pages. You'll find plans for building a nest box of the appropriate size on our All About Birdhouses site.

Cool Facts
- Young Common Mergansers leave their nest hole within a day or so of hatching. The flightless chicks leap from the nest entrance and tumble to the forest floor. The mother protects the chicks, but they catch all of their own food. They start by diving for aquatic insects and switch over to fish at about 12 days old.
- Common Mergansers are sometimes called sawbills, fish ducks, or goosanders. The word “merganser” comes from the Latin and roughly translates to “plunging goose”—a good name for this very large and often submerged duck.
- You may see gulls trailing flocks of foraging Common Mergansers. They wait for the ducks to come to the surface and then try to steal their prey rather than fishing on their own. Occasionally even a Bald Eagle will try to steal a fish from a merganser.
- Common Mergansers usually nest in natural tree cavities or holes carved out by large woodpeckers. Sometimes mergansers take up residence in nest boxes, provided the entrance hole is large enough. On occasion they use rock crevices, holes in the ground, hollow logs, old buildings, and chimneys.
- The oldest Common Merganser on record was a female, and at least 13 years, 5 months old. She was banded in Oklahoma in 1938 and found in Wisconsin in 1950.