Red-Breasted Merganser (Mergus serrator)

This merganser is found further north than most of its relatives. It is also the most common merganser in oceanic environments in the winter.


Reaching up to 60 cm in length, males of this species are slightly larger than females. The breeding male has a dark metallic green head with a backswept crest. It has a white band around its neck, a reddish breast, grey flanks, and a black back with a row of white spots at its shoulder. The female has a pale brown head also with a backswept crest, a buff breast, and grey flanks and back. Its wings are grey with a white patch or speculum. The non-breeding male is similar to the female except his wings retain the breeding pattern and colouration.


The red-breasted merganser breeds in northern Canada, along the Pacific coast, and in parts of the prairies, Ontario, Quebec, and the Maritimes. In winter, this species frequents the east and west coasts of North America.


The red-breasted merganser is believed to be monogamous, and nests on rivers, ponds, and lakes. Preferred nesting sites are on small islands with shrubby vegetation or along the shore of salt-water bays. The female builds the nest on the ground in a concealed spot; it is a scrape in the ground, lined with plants, down, and feathers. Eight to ten olive eggs are laid, and are incubated by the female for about a month. The male leaves the female once incubation has begun, and is only rarely seen at the nest thereafter. The young are able to feed and move about themselves, and require about two months before they can leave the nest.

The red-breasted merganser eats mostly fish, but supplements its diet with crustaceans and aquatic insects. Young birds eat the same foods as adults. Red-breasted mergansers dive from the surface of the water to capture fish, and retrieve food from the substrate and the water column. Groups of red-breasted mergansers have been observed feeding cooperatively, herding fish into shallow water where they are easier to catch.