Red-breasted Merganser

The Red-breasted Merganser is a slim, shaggy-crested fish-eating duck of coastal waters and northern lakes. Breeding males have a glossy dark green head with a wild, spiky double crest, a white collar, a rusty-orange speckled breast band, and finely vermiculated gray flanks. Females and eclipse males are grayish-brown with a rusty head that blends more gradually into a paler throat than in the Common Merganser, and their crest is longer and messier.

Like other mergansers, this species has a thin, serrated, hook-tipped bill adapted for catching fish underwater. It is the most marine of the three mergansers, frequently seen bobbing in small flocks on bays, harbors, and open coastal water.

Key field marks

• Long, thin, bright red-orange bill with a hooked tip
• Breeding male: green head with unkempt double crest, white neck ring, streaked rusty breast band, gray (not white) flanks
• Female/eclipse: rusty-brown head blending gradually into whitish throat, shaggy crest
• Slim, low profile on the water; fast, direct flight with rapid wingbeats

Similar species

Compare with the Common Merganser, which is bulkier, has clean white flanks in the male, and a smoother, less messy crest; females have a more sharply cut-off white chin. The Hooded Merganser is notably smaller with a bold fan-shaped crest and thinner bill. In flight, Red-breasted Mergansers look slimmer and more attenuated than Common Mergansers.

Red-breasted Mergansers breed across the boreal and subarctic zones of North America, Europe, and Asia, nesting on the ground near lakes, rivers, and coastal tundra. They are highly migratory and winter predominantly along marine coastlines, estuaries, and large bays, making them the most saltwater-associated of the mergansers. Large numbers gather in sheltered coastal waters in winter, sometimes far offshore.

Behavior

These ducks dive to chase down fish, often foraging in loose groups and sometimes cooperatively driving schools of small fish into the shallows.

Voice

Mostly silent outside the breeding season; males give rasping, cat-like calls during courtship, and females utter harsh croaks.

Feeding

Primarily small fish, along with some aquatic invertebrates; the serrated bill edge helps grip slick prey.

Nesting

Nests on the ground, well concealed in vegetation near water, unlike the tree-cavity nesting Common and Hooded Mergansers. Clutches average 7-10 eggs, and broods often combine ('creche') with those of other females after hatching.