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A photo of a Red-breasted Merganser (Mergus serrator), male
Red-breasted Merganser, Male

Red-breasted Merganser

Mergus serrator

The Red-breasted Merganser, Mergus serrator, is a distinctive duck with a slender, serrated red bill and a spiky crest. Males in breeding plumage exhibit a dark head with a green sheen, a white neck, a rusty breast, a black back, and white underparts. Females and juveniles are more subdued, with females sporting a rusty head and a greyish body, while juveniles resemble females but lack the white collar and have smaller white wing patches.

Identification Tips

Adult males are unmistakable with their contrasting colors and spiky crests. Females and non-breeding males can be confused with the similar Common Merganser, but the Red-breasted Merganser lacks the light chin patch of its relative and has less contrast between the head and breast.


The Red-breasted Merganser breeds on freshwater lakes and rivers across northern regions. It is unique among its genus for its frequent use of saltwater during winter months.


This species has a broad range across the Northern Hemisphere, migrating from northern breeding grounds to mostly coastal wintering areas.


Outside of breeding season, Red-breasted Mergansers form flocks, typically small but occasionally numbering up to 100 individuals. They are known for their rapid flight and are capable of diving and swimming underwater to pursue prey.

Song & Calls

The female's courtship call is a rasping "prrak prrak," while the male produces a catlike "meow." In flight, females emit a harsh "gruk." Generally, this species is quiet when not breeding.


Nesting occurs in sheltered spots near water, with migration to coastal waters in the south during winter. Flock sizes vary, being smaller in spring migration compared to autumn and winter.

Similar Species

The Common Merganser is the most similar species, but differences in plumage and habitat preference can aid in distinguishing between the two.

Diet and Feeding

Their diet consists mainly of small fish, supplemented by aquatic insects, worms, crustaceans, and amphibians.

Conservation status

The Red-breasted Merganser is classified as Least Concern by the IUCN. It is subject to the AEWA and is a game bird in North America, though it is not commonly hunted. Threats include habitat loss, exposure to toxins, and bycatch in fishing operations.

Red-breasted Merganser Sounds

Recorded by: © 
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Red-breasted Merganser Fun Facts

Did you know?
The scientific name of the Red-breasted Merganser means 'serrated bill'.

Red-breasted Mergansers on Birda


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