Birds  /  Waterfowl  /  Red-breasted Merganser

Red-breasted Merganser

Mergus serratorNativeLeast Concern

About the Red-breasted Merganser

The Red-breasted Merganser is a shaggy-crested fish-eating duck of open water, most at home on the cold, wave-tossed expanses of the Great Lakes. The drake is dashing, with a dark green head raised into a spiky double crest, a bright white collar, a streaked rusty chest, and a thin red serrated bill; the hen is grayer with a rusty head that blends softly into the neck, always looking a bit unkempt. Both wear the narrow, saw-toothed "sawbill" of the merganser tribe, perfect for gripping slippery fish.

Red-breasted Mergansers dive and pursue fish underwater, sometimes in coordinated groups that herd prey into the shallows, and they are strong, fast fliers. They breed along the Great Lakes shorelines and on northern waters, and in migration and winter great numbers gather on the lakes and bays — spring flights along the Great Lakes can be spectacular. Compared with the Common Merganser, the Red-breasted is shaggier, favors bigger open water, and is far more numerous on the Great Lakes.


Diet

FishCrustaceansAquatic insects

Dives to pursue and capture fish, its primary food, with the serrated bill, and also takes crustaceans and aquatic insects. It often hunts cooperatively, with groups driving fish into shallow water where they are easier to catch, and it can eat a substantial number of small fish each day.

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Questions birders ask

How do I tell it from a Common Merganser?

The Red-breasted has a shaggy, spiky double crest and (in the drake) a streaked rusty chest and white collar, and it favors big open water like the Great Lakes. The Common Merganser is sleeker, with a clean white body and a smoothly rounded green head, and prefers rivers and inland lakes.

Where is it most common in Michigan?

On the Great Lakes and large bays, especially in migration and winter, when big numbers gather. It also breeds along Great Lakes shorelines and on northern waters.

What does it eat?

Mainly fish, caught on underwater dives and gripped with its serrated bill, along with some crustaceans and aquatic insects. Groups sometimes herd fish into the shallows to hunt them cooperatively.

How do I tell young Red-breasted Mergansers apart?

Juveniles and eclipse males resemble the shaggy gray-and-rust female, with a less contrasting neck than a female Common Merganser. Adult male plumage is back in place by the time flocks build on the Great Lakes in winter.

What do you call a flock of Red-breasted Mergansers?

A raft. Their spring migration along the Great Lakes shoreline produces some of the largest concentrations of any duck in Michigan, moving in long low strings.

Easily confused with

Other birds you might be looking at instead.

Common MerganserMergus merganser
Hooded MerganserLophodytes cucullatus
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