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Red-breasted Merganser

Mergus serrator

Length: 17 to 25 inches Wingspan: 30 to 36 inches Seasonality: Migrant
ID Keys: Reddish chest on male, gray sides, black head with white collar, thin serrated bill.

Red-breasted Merganser - Mergus serratorThe Red-breasted Merganser is most often seen along coastlines of the U.S. in the winter, as they prefer to winter on salt-water (unlike the Common Merganser).   They sometimes hunt cooperatively, forming lines to drive small prey fish into shallow water.  They are among the fastest of all flying waterfowl, reaching speeds of up to 100 mph.

In South Dakota, Red-breasted Mergansers are migrants, more commonly found in the eastern part of the state than the west. They sometimes may be one of the earliest waterfowl to start to move northward through the state.


During breeding season, they are found around lakes and rivers in the forests of Northern North America, northward into the tundra.  During winter, they are primarily found on coastal waters, with smaller numbers on inland waters if they are ice-free. Red-breasted Mergansers are more likely to be found in salt-water habitats than other merganser species in North America.


Red-breasted Mergansers feed primarily on small fish.  They will also take crustaceans, aquatic insects, frogs, and tadpoles. Young birds take insects and small crustaceans until they approach the adult's larger size.


 Feeds by diving and pursuing prey underwater.  Occasionally Red-breasted Mergansers appear to cooperatively, collectively driving small fish to shallower water for easier capture. They are very strong fliers, and are one of the fastest flying waterfowl in North America.


Non-breeder in South Dakota. On their breeding grounds, Red-breasted Mergansers nest on the ground, using a variety of locations as long as the nest site is near water. The nest is placed in a protected area such as at the base of a dense bush, nest to or under a brush pile, under a fallen log, are in a protected spot in a rocky crevice. The nest is a shallow scrape, lined with dead grasses and weedstems, and finished with down. The female lays between 4 and 16 eggs, and she alone incubates them. The young hatch after about four weeks, and leave the nest soon after hatching. The female protects the young while they gather their own food. The male is nowhere to be soon once the nest site is selected and all eggs have been laid.


Generally silent, although the courting male will make cat-like calls.


Summers throughout Alaska, much of Canada, the Great Lakes region, and New England.  Winters along both the Atlantic and Pacific coasts of North America, with much smaller numbers over-wintering on the Great Lakes and other inland water bodies.

Interactive eBird Map:

Click here to access an interactive eBird map of Red-breasted Merganser sightings

Similar Species:

Females are generally more of an identification challenge than are the male Red-breasted Mergansers. Potential confusion could be with the other merganser species possibly found in South Dakota:

Common Merganser 2 - Mergus merganser Common Merganser 5 - Mergus merganser Hooded Merganser 2 - Lophodytes cucullatus Hooded Merganser 1 - Lophodytes cucullatus
Common Merganser (female) Common Merganser (male) Hooded Merganser (female and young) Hooded Merganser

Conservation Status:

Systematic surveys in recent decades show populations of Red-breasted Merganser are generally stable. They are found across a very broad geographic area, and are common in parts of that range. The IUCN considers the Red-breasted Merganser to be a species of "Least Concern".

Further Information:

Photo Information:

Photo taken on April 12th, 2012 - Sachuest National Wildlife Refuge, Rhode Island - Terry Sohl

Audio File Credits:

Click on the map below for a higher-resolution view
 Red-breasted Merganser - Range Map
South Dakota Status: Uncommon migrant in the eastern half of the state, rare migrant in the west.  Rare winter visitor along the Missouri River.

Additional Red-breasted Merganser Photos
Click for a higher-resolution version of these photos
 Red-breasted Merganser 1 - Mergus serratorRed-breasted Merganser 2 - Mergus serratorRed-breasted Merganser 3 - Mergus serratorRed-breasted Merganser 4 - Mergus serratorRed-breasted Merganser 5 - Mergus serratorRed-breasted Merganser 6 - Mergus serratorRed-breasted Merganser 7 - Mergus serrator