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Dig Imperial Beach

An Imperial Beach Hidden Gem and Bird of the Week, the Red-Breasted Merganser

Mar 02, 2017 11:19AM ● By Paul Spear


The Red-Breasted Merganser

This week’s “Bird of the Week” is the Red-breasted merganser (Mergus serrator), a diving duck, and one of the sawbills. They are a slim, crested, fish-eating duck, commonly seen 

around jetties and piers along the coast. Superficially this species is quite similar to the Common Merganser. However, the Red-breasted Merganser nests farther north, winters mostly on salt water, and nests mainly on the ground, while the Common winters mostly on fresh water and nests in cavities. Their 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.

Habitat is on lakes, open water; and in winter, on coastal bays. During nesting season they can be found around lakes and rivers, within the northern forest and northward into tundra regions. In winter they can be found mostly on coastal waters, including bays, estuaries, and open ocean; a few winter on ice-free reservoirs and large rivers.

Red-breasted mergansers forage by diving and swimming underwater. Sometimes a group appears to hunt cooperatively, with several birds lining up and driving schools of small fish into very shallow water, where the mergansers scoop them up without diving. Diet is mostly fish, feeding mainly on small fish, but also on crustaceans, aquatic insects, and sometimes frogs, tadpoles, or worms. Young ducklings eat mostly insects.

In courtship display, males stretch their necks forward and upward, then suddenly dip their necks and the forepart of their bodies underwater, with heads angled up out of water and bills open wide. Females select nesting sites on ground, usually near water, in a spot sheltered by dense plant growth or debris. Sometimes nests are inside hollow stumps, under rocks, or in shallow burrows. Nests are a simple depression, lined with down.

After mating, females usually lay 7-10, sometimes 5-13, olive-buff eggs. Females sometimes 

lay eggs in each others' nests, and occasionally in the nests of other breeds of ducks. Incubation is by females only, in about 29-35 days. Within a day after eggs hatch, females lead their 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 in about 2 months after hatching.

I have recently spotted a few Red-breasted mergansers in our terrific Tijuana Estuary. Look for them there while walking or biking on the many paths there. Until next week, happy birding!



Bryan Brillhart Photography or Bird of the Week


Bryan Brillhart



