Red-breasted Merganser
Mergus serrator

Conservation status | Numbers are thought to be stable, but the species could be vulnerable because it forms such dense concentrations at certain times and places during migration, such as late fall on Lake Erie. |
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Family | Ducks and Geese |
Habitat | Lakes, open water; in winter, coastal bays. During nesting season around lakes and rivers, within the northern forest and northward into tundra regions. In winter mostly on coastal waters, including bays, estuaries, and open ocean; a few winter on ice-free reservoirs and large rivers. |
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Feeding Behavior
Forages by diving and swimming underwater. Sometimes a group appears to hunt cooperatively, several birds lining up and driving schools of small fish into very shallow water, where the mergansers scoop them up without diving.
Eggs
usually 7-10, sometimes 5-13. Olive-buff. Females sometimes lay eggs in each others' nests, occasionally in nests of other ducks. Incubation is by female only, 29-35 days. Young: Within a day after eggs hatch, female leads young to water, where they feed themselves. 2 or more broods may join, tended by 1 or more adult females, but young are left on their own within a few weeks. Young are capable of flight about 2 months after hatching.
Young
Within a day after eggs hatch, female leads young to water, where they feed themselves. 2 or more broods may join, tended by 1 or more adult females, but young are left on their own within a few weeks. Young are capable of flight about 2 months after hatching.
Diet
Mostly fish. Feeds mainly on small fish, also crustaceans, aquatic insects, and sometimes frogs, tadpoles, or worms. Young ducklings eat mostly insects.
Nesting
In courtship display, male stretches neck forward and upward, then suddenly dips neck and forepart of body underwater, with head angled up out of water and bill open wide. Nest: female selects site on ground, usually near water, in a spot sheltered by dense plant growth or debris. Sometimes nests inside hollow stump, under rock, or in shallow burrow. Nest is a simple depression, lined with down.
Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds
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Migration
May migrate later in spring and earlier in fall than the Common Merganser. Migrating flocks fly in V-formation or lines.

- All Seasons - Common
- All Seasons - Uncommon
- Breeding - Common
- Breeding - Uncommon
- Winter - Common
- Winter - Uncommon
- Migration - Common
- Migration - Uncommon
See a fully interactive migration map for this species on the Bird Migration Explorer.
Learn moreSongs and Calls
Usually silent; various croaking and grunting notes during courtship.Learn more about this sound collection.