Red-breasted Mergansers

The Red-breasted Merganser (Mergus serrator) is a diving duck

It has been claimed to be the fastest bird in level flight, reaching speeds of 129 km/h (80 mph), but is disputed whether the White-throated Needletail (Swift) is faster, reportedly flying at 170 km/h (105mph).

Distribution / Range

Its breeding habitat is freshwater lakes and rivers across northern North America, Greenland, Europe and Asia.

It nests in sheltered locations on the ground near water.

It is migratory and many northern breeders winter in coastal waters further south.


The Red-breasted Merganser is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

Red-breasted Merganser global distribution map

More Duck Resources


The adult Red-breasted Merganser is 52-58 cm long with a 67-82 cm wingspan. It has a spiky crest and long thin red bill with serrated edges. Adult males have a dark head with a green sheen, a white neck with a rusty breast, a black back and white underparts.

Adult females have a rusty head and a greyish body.

Juveniles are like the female, but lack the white collar and have a smaller white wing patch.

Female Red-breasted Merganser (Mergus serrator) with fish in her beak

Female Red-breasted Merganser (Mergus serrator)

Diet / Feeding

Red-breasted Mergansers dive and swim underwater. They mainly eat small fish, but also aquatic insects, crustaceans and frogs.

Calls / Vocalization

The call of the female is a rasping prrak prrak, and the male gives a feeble hiccup-and-sneeze display call.

Red-breasted Merganser

Female Red-breasted Merganser (Mergus serrator) - Female

Diet / Feeding:

Red-breasted Mergansers dive and swim underwater when foraging for their staple foods mainly consisting of small fish, aquatic insects, crustaceans and frogs.

Ducks generally feed on larvae and pupae usually found under rocks, aquatic animals, plant material, seeds, small fish, snails and crabs.

Feeding Ducks …

We all enjoy ducks and many of us offer them food to encourage them to come over and stay around – and it works! Who doesn’t like an easy meal!

However, the foods that we traditionally feed them at local ponds are utterly unsuitable for them and are likely to cause health problems down the road. Also, there may be local laws against feeding this species of bird – so it’s best to check on that rather than facing consequences at a later stage.

Please note that feeding ducks and geese makes them dependent on humans for food, which can result in starvation and possibly death when those feedings stop. If you decide to feed them, please limit the quantity to make sure that they maintain their natural ability to forage for food themselves – providing, of course, that natural food sources are available.

male Red-breasted Merganser at Browns Point Marina, Keyport, New Jersey, USA in winter.
3 Male Red-breasted Merganser and 1 Female (top), Mergus serrator
Red-breasted Merganser (Mergus serrator)
Red-breasted Merganser Couple
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Gordon Ramel

Gordon is an ecologist with two degrees from Exeter University. He's also a teacher, a poet and the owner of 1,152 books. Oh - and he wrote this website.

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