Where’s Wildlife · Bird Field Guide
Red-breasted Merganser
Mergus serrator
Pronounced (approx.): MER-gus seh-RAY-tor
A slender diving duck with a shaggy crest and a narrow bill suited to catching fish.
Three Identification Clues
A long, narrow red bill and a ragged crest give the head a distinctive profile.
Breeding males have a green head, white neck ring, and reddish-brown chest.
Females have a brown head blending gradually into a grayish breast, unlike the sharper contrast of Common Mergansers.
Field Photographs
Showing all 7 photographs.
Beyond the first impression
Plumage & Identification
The rusty chest is only one plumage
A breeding male combines a green head, white collar, and cinnamon-colored chest. Females and nonbreeding males are much browner. The thin bill and ragged crest remain useful when the bright pattern is absent, while developing males may show an uneven mixture of colors. [1]
Compare the whole brown-headed bird
In Red-breasted Merganser, the brown head generally blends gradually into the chest. A female Common Merganser usually has a more distinct white chin and sharper neck boundary. Young Common Mergansers can blur those differences, so compare several views in our Common Merganser guide and check the bill as well. [4]
Life history
How This Bird Lives
Where to look
Scan sheltered coastal bays, estuaries, and large inland lakes during migration and winter. This species uses salt water more often than Common Merganser, but habitat alone does not identify a bird. Breeding sites include northern freshwater and coastal wetlands. [2]
Food & foraging
A feeding bird may swim with its eyes below the surface before diving. Small fish dominate the diet, and the bill's toothlike edges help retain slippery prey. Watching a series of dives reveals more than a single surfacing bird. [2]
Usually on the ground, not in a tree
The female chooses a sheltered spot near water, often under plants or debris, and adds down to a shallow hollow. Audubon describes 7–10 eggs as usual; females sometimes lay in one another's nests, producing larger totals. [4]
She incubates for about 29–35 days. Ducklings go to water within a day of hatching and feed themselves. Keep a respectful distance from families and shoreline nesting cover. [4]
Did you know?
A Closer Look at Red-breasted Mergansers
Fish can be herded
Groups sometimes line up and drive small fish into shallower or confined water. Several birds feeding together may be benefiting from a shared hunting opportunity rather than merely occupying the same bay. [2]
A courtship curtsy
A displaying male raises his head, dips his chest, and tips his rear upward. The exaggerated motion is a courtship signal, not an ordinary feeding dive. [2]
Adult appearance takes time
Full breeding plumage is not acquired until about two years of age. A young male does not immediately become a miniature version of the most colorful bird in a field guide. [3]
Sources: [1] Cornell · Identification [2] Cornell · Life history [3] Cornell · Species overview [4] Audubon · Field guide
Range & Sightings
Seasonal Range
View Range Map ↗Recorded Observations
Observation records are not a complete seasonal range map.
iNaturalist observation map ↗