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Red-Breasted Merganser

Mergus serrator

A speedy migratory wildfowl with a hardcore hairstyle, the Red-breasted Merganser is widespread in coastal and estuarine habitats across the Northern Hemisphere.

Female Red-Breasted Merganser

Juvenile Red-Breasted Merganser

Red-Breasted Merganser duckling

Red-Breasted Merganser in-flight

Red-Breasted Merganser performing courtship display

Quick Facts

Classification

Scientific name:

Mergus serrator

Other names:

Sawbills, Fish Ducks, Sheldrakes

Family:

Ducks, geese and swans

Conservation status:

Green

Measurements

Length:

51cm to 64cm

Wingspan:

70cm to 86cm

Weight:

800g to 1.35kg

Appearance & Identification

Calls & Sounds

Diet

Habitat & Distribution

Other birds in the Ducks, geese and swans family

Appearance & Identification

What do Red-breasted Mergansers look like?

Red-breasted Mergansers are distinctive wildfowl with narrow, serrated bills and spiky crests. Breeding males are attractively patterned with a bright red bill and eyes, a dark green head, complete with an untidy crest, and a white collar. Their flanks appear gray, bordered above by a bold white horizontal streak on the wing and then a pure black back. The shoulder is black, with contrasting white spots, and the lower neck and breast are reddish brown.

Females have gray-brown upperparts with distinctive brick-red heads and coral-red bills. The throat, breast, and underparts are a paler whitish shade. Immature males and females resemble adult females, as do non-breeding males, although they are larger and have darker crowns.

This species is most easily confused with the Common Merganser/ Goosander and the female Hooded Merganser.

Red breasted merganser swimming in open water

Male Red-Breasted Merganser

Female Red-Breasted Merganser

How big are Red-breasted Mergansers?

Red-breasted Mergansers are long and lean ducks, slightly smaller than Mallards.

Length

They have a total length of 20 to 25 inches or 51 to 64 centimeters. Males are larger than females.

Weight

Males generally weigh 33½ to 47 ounces or 950 to 1350 grams, while females weigh 32 to 39 ounces or 900 to 1100 grams.

Wingspan

They have a fairly short wingspan of 27½ to 34 inches or 70 to 86 centimeters.

Red-Breasted Merganser standing on a rock by the sea

Calls & Sounds

What sound does a Red-breasted Merganser make?

Red-breasted Mergansers are quiet for most of the year. Both sexes are more vocal during courtship displays when males produce a ‘meow’ call and females make a croaking call. They also make a grunting alarm call if threatened.

Female Red-Breasted Merganser calling

Diet

What do Red-breasted Mergansers eat?

Red-breasted Mergansers are mostly carnivorous, hunting small fish in the four to six-inch (10 - 15 cm) range. They also eat other small marine or aquatic animals like frogs, worms, crustaceans, and insects.

These birds swim with their heads lowered below the surface, watching for fish or other prey. Once sighted, they may dive down, kicking with their webbed feet and snapping at their prey with their toothy bill. They can dive to about 30 feet (9 m) but usually hunt closer to the surface.

What do Red-breasted Merganser chicks eat?

Red-breasted Merganser ducklings eat small fish, insects, and seeds. They leave the nest soon after hatching and begin to hunt for themselves as soon as they move to the water.

Female Red-Breasted Merganser diving for fish

Habitat & Distribution

What is the habitat of a Red-breasted Merganser?

Red-breasted Mergansers generally live in shallow marine and estuarine environments in the winter but many switch to freshwater bodies like lakes and larger rivers near the coast and further inland in the breeding season.

What is the range of a Red-breasted Merganser?

Red-breasted Mergansers are extremely widespread in the Northern Hemisphere, breeding from Iceland and the United Kingdom in the west to the Bering Sea off Russia. In the New World, they occur from the west coast of Alaska to the east coast of Canada. They range south to Mexico, the Mediterranean, and Southeast Asia in the winter.

Where do Red-breasted Mergansers live?

Red-breasted Mergansers spend most of their time in shallow brackish, saltwater, and freshwater environments. They are excellent swimmers, with large webbed feet set well back toward their tails. Away from the water, these birds are awkward on land and rarely walk. However, they are powerful in flight, reaching impressive speeds of over 80 miles per hour (130 km/h)! They are probably the fastest ducks and one of the world’s fastest birds.

How rare are Red-breasted Mergansers?

Their world population is estimated at about 500,000 to 600,000 individuals, of which about a third live in Europe. This species can be common in suitable habitats, although they disappear from most areas for part of the year on migration.

Red-Breasted Merganser in the lake flapping his wings

Where can you see Red-breasted Mergansers in the US?

Red-breasted Mergansers are a widespread breeding visitor in Alaska, especially in coastal areas. They are mostly winter visitors to the East and West Coasts of the Lower 48, although they do breed and overwinter around the Great Lakes and the far Northeast. They are rare inland, although small numbers overwinter and migrate across the interior.

Where can you see Red-breasted Mergansers in Canada?

Look out for these migratory wildfowl along the entire west coast and around the Gulf of St. Lawrence and Newfoundland in the winter. They are also widespread breeding birds in Canada’s interior, although absent from much of British Columbia, Alberta, and Saskatchewan.

Where can you see Red-breasted Mergansers in the UK?

British birdwatchers can spot Red-breasted Mergansers practically anywhere off the UK coast in the winter. They are much rarer in the summer when about 1650 pairs nest on Scotland’s lochs and isolated locations in western England, Wales, and Northern Ireland.

Female Red-Breasted Merganser in nesting habitat

Lifespan & Predation

How long do Red-breasted Mergansers live?

Ringing/banding records suggest that Red-breasted Mergansers can live a maximum of about 12 years.

What are the predators of Red-breasted Mergansers?

Gyrfalcons, Great-horned Owls, and Red Foxes are known predators of adult Red-breasted Mergansers. Their eggs and young are vulnerable to a greater variety of predators, including Herring Gulls, Great Black-backed Gulls, and Parasitic Jaegers/ Arctic Skuas.

Are Red-breasted Mergansers protected?

Red-breasted Mergansers are protected in the United Kingdom, The United States, and Canada.

Are Red-breasted Mergansers endangered?

These widespread diving ducks are not endangered. They are a ‘Least Concern’ species with an extensive global range and a stable population.

Red-Breasted Merganser male (left) and female (right)

Nesting & Breeding

Where do Red-breasted Mergansers nest?

Red-breasted Mergansers nest on the ground within about 100 feet (30 m) of the water and often much closer. The female selects a well-hidden site under cover or among dense vegetation. She usually constructs a shallow scrape and gradually lines it with soft plant material and her own down feathers.

When do Red-breasted Mergansers nest?

The warm months of spring and summer provide ideal nesting conditions for Red-breasted Mergansers. Females lay their eggs from mid-May to early July, depending on latitude. They incubate the eggs alone for about a month, and the hatchlings leave the nest within a day of hatching.

What do Red-breasted Merganser eggs look like?

Red-breasted Mergansers lay a single clutch of anything from 5 to 25 pale brown or grayish eggs each year. Each egg measures approximately 63 millimeters long and 45 millimeters wide.

Do Red-breasted Mergansers mate for life?

Red-breasted Mergansers do not mate for life. Pairs usually form in early spring and break up once the eggs have been laid.

Nest of a Red-Breasted Merganser with 13 eggs

Behavior

Are Red-breasted Mergansers aggressive?

Red-breasted Mergansers are gregarious and non-territorial throughout the year. They are not particularly aggressive, although males may use aggression to deter competitors when pairing or to defend their immediate personal space. They will also defend the space around their nest, although they may nest within about a foot of each other in dense colonies.

Red-Breasted Merganser

Migration

Do Red-breasted Mergansers migrate?

Red-breasted Mergansers are migratory across their range. They usually migrate in pairs or small flocks, although larger flocks up to about 500-strong have been observed in North America.

Why do Red-breasted Mergansers migrate?

Shallow water bodies in the boreal zone provide ideal nesting conditions in the spring and summer but become inhospitable in the cold winter months. Coastal areas in the temperate south provide a more comfortable environment and better fishing opportunities for vulnerable first-year birds. Warmer overwintering grounds also allow adults to improve their condition ahead of the next breeding season.

Where do Red-breasted Merganser migrate to?

Red-breasted Mergansers migrate to their northern breeding grounds for the spring and summer. These areas are located primarily in Alaska, Canada, Northern Europe, Greenland, Iceland, and Russia, although they also breed further south in the Northeast and Midwest of the United States and in parts of Western and Central Europe and Central Asia.

In the fall/autumn, they return to coastal areas at temperate latitudes on both coasts of North America, from Alaska to Mexico in the west and from the Gulf Coast to the Northeast on the Atlantic coast. In the Old World, these birds overwinter in scattered areas from the United Kingdom to the Mediterranean and from the Middle East to Southeast Asia.

Red-Breasted Merganser in-flight

FAQs

What is the difference between Red-breasted and Common Merganser?

Red-breasted Mergansers and Common Mergansers (also known as the Goosander in the United Kingdom) are similar species that occur over much of the Northern Hemisphere.

You’re most likely to see the Red-breasted Merganser in saltwater or estuarine environments, where their long, scruffy crest and straight bill are useful clues to look for. The Common Merganser (Mergus merganser) is a much larger species that usually inhabits freshwater habitats. These birds also have hooked bills, and males have rounded crests.

Is the Red-breasted Merganser a duck?

Red-breasted Mergansers are ducks, despite their unusually thin bills. These attractive wildfowl are from the Anatidae family, the same group that contains all ducks, geese, and swans.

What’s another name for a Red-breasted Merganser?

Red-breasted Mergansers are sometimes called sawbills, fish ducks, or sheldrakes.

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Facts

What is a Group of Ducks Called? (Complete List + Why?)

Other birds in the Ducks, geese and swans family

Wigeon

The Eurasian wigeon is a medium dabbling duck that commonly breeds across northern Europe, and winters further south, including in the British Isles and occasionally in North America. Rare vagrant breeding pairs can be found in the United States, and small breeding grounds have also been established in northern England and Scotland.

Whooper Swan

This large bird arrives on our shores from Iceland to overwinter in late September, returning northwards to breed from mid March onwards.

Greater White-Fronted Goose

One of several similar wildfowl species in the Anser genus, Greater White-fronted Geese live up to their name with a distinctive white patch on the front of their face. The species is extremely widespread, although there are several sub-species, each with different breeding and overwintering ranges.

Velvet Scoter

Larger than the Common Scoter this elegant European diving duck spends much of its time at sea and is often seen in company with mixed flocks resting on the water’s surface far out from land.

Tundra Bean Goose

The tundra bean goose is the most common species of bean goose, and breeds on Russian tundra landscapes. Winters are spent grazing on open fields, marshes and agricultural land in western and central Europe and East Asia.

Tufted Duck

The Tufted Duck is the UK’s most common diving duck and a familiar sight on lakes and ponds across the country. Known for their long, hair-like tufts, these small waterfowl are fairly easy to identify but may be confused with other ducks from the Aythya genus.

Eurasian Teal

Fast and erratic in flight, the Teal is the United Kingdom’s smallest wildfowl species. Despite occurring year-round in low numbers, birdwatchers are most likely to spot these tiny ducks in the winter when large numbers arrive from abroad.

Taiga Bean Goose

Taiga bean geese are a common sight on northern taiga marshes of Siberia and northern Scandinavia in spring and summer, before heading south into Europe each winter. Several hundred individuals spend winters in the UK, with rare vagrant visitors occasionally reported in North America.

Snow Goose

One of seven American goose species, the Snow Goose is a noisy migrant that visits the Lower 48 states each winter. These beautiful birds have increased dramatically since the second half of the 20th century.

Smew

Despite being only a rare winter visitor to the British Isles, the Smew is one of the countrys most unmistakable and easily identified duck species. Breeding across Central Asia and returning to Western Europe during winter months, smews begin to turn up on inland lakes as well as in coastal regions from November onwards.

Northern Shoveler

One look at the bill of a northern shoveler should be enough to provide you with an accurate species identification: their flattened shovel-like bills are unique among waterfowl and allow them to feed on tiny plankton by sweeping their heads across the water’s surface.

Shelduck

A large colourful duck, often found in coastal areas, the shelduck, is an established breeding waterbird in the UK. British wetlands are also a major wintering ground for the species, hosting up to 30 percent of Europe’s shelduck population each autumn.

Greater Scaup

A medium-sized diving duck, the greater scaup is known simply as the scaup in Europe, and locally as the ‘bluebill’ in North America. Only a handful of scaup breed in the UK, making it the rarest breeding duck in the British Isles.

Ruddy Duck

A striking and fascinating little diving duck with an unusual courtship display, the Ruddy Duck is a widespread migrant in North America.

Red-Crested Pochard

Colourful and instantly recognisable diving ducks, red-crested pochards are present in the UK in small numbers, believed to have initially been introduced into the wild from private wildfowl collections. Some breeding does occur in Britain, although the best chance of a sighting comes with the arrival of several hundred migrants each winter.

Pochard

During the winter the population of this rare resident breeding duck increases by 55 times to that of the summer, with the influx of many thousands of others overwintering, having arrived from Russia and Eastern Europe.

Pintail

Widespread in the Northern Hemisphere, Northern Pintails are distinctive migratory waterfowl. Drakes in breeding plumage are particularly attractive, although the drabber females and non-breeding males are still identifiable by their long necks and graceful form.

Pink-Footed Goose

Although the pink-footed goose does not breed in Britain, it is a common winter visitor, with over half a million migrating individuals arriving each autumn from breeding grounds in Iceland, Greenland and Norway’s Svalbard peninsula.

Mute Swan

One of the world’s heaviest flying birds, and one of the most beautiful too, the Mute Swan is a majestic waterfowl with a mean reputation.

Mandarin Duck

Sightings of wild Mandarin Ducks in the United States cause quite a stir, and it’s easy to see why. These small but eye-catching waterfowl are, in fact, native to the Far East of Asia, although their popularity as an ornamental species has resulted in their introduction to many parts of the world, including the United Kingdom.

Mallard

Instantly recognizable, the Mallard is a medium-sized dabbling duck that is familiar to people all over the world. These adaptable waterfowl are the ancestor of the modern domestic duck and are found everywhere from remote wilderness lakes to suburban backyards.

Long-Tailed Duck

One of the most distinctive duck breeds, thanks to their extended streaming tail feathers, the long-tailed duck is a coastal waterbird that spends winters at sea, foraging for crustaceans in marine waters, after breeding on Arctic tundra landscapes.

Greylag Goose

The Greylag goose is the largest grey goose from the Anser genus of the Anatidae family of waterbirds. A stout, robust and heavyweight bird, the Greylag goose is the closest wild relative and ancestor to the domestic goose. Greylag geese are distributed across much of Europe and Asia, extending into eastern Russia and China. Most populations migrate, but some are sedentary, including in much of Northern Europe.

Merganser

Widespread throughout the northern hemisphere, the common merganser is the largest of the saw billed fish eating ducks. There are three sub-species with the Eurasian variant frequently known as the Goosander.

Goldeneye

Goldeneyes are distinctive diving ducks that thrive in cold environments, breeding in boreal forests across Canada, northern Scandinavia and northern Russia. Only when the lakes and coastal areas on their summer territories begin to freeze over as fall approaches do they begin to head south to milder regions where they spend winter months foraging on inland lakes and around sheltered bays.

Garganey

The Gargeney is a dabbling duck, slightly smaller than a mallard, and considered a rare breeder in the UK, with just over 100 pairs recorded. A fully migratory species, all garganeys spend winters in southern Africa, leaving breeding grounds as early as July, so your window for spotting one on British waters is only a very brief one.

Gadwall

The Gadwall is a widely distributed dabbling duck of the Anatidae family that breeds in the Northern Hemisphere. This hardy duck breeds as far north as Siberia, Alberta, Saskatchewan, and coastal Alaska and is found across both the Americas, Europe, and Asia.

Eider

The common eider (Somateria mollissima) is a large and widespread sea duck that is perhaps best known for its valuable insulating down feathers.

Egyptian Goose

Regarded as being sacred by early Egyptians, this native goose of the African continent was introduced into Europe and elsewhere as an ornamental wildfowl species in the late seventeenth and eighteenth century.

Common Scoter

The word scoter is often used to define northern sea ducks. There are six different species of scoter, all of which are monotypic and three of which are confined to North America. The Common Scoter like the Velvet Scoter can only be found in Europe and Asia whilst the Stejneger’s Scoter is a native of Asia alone.

Canada Goose

Once decimated through overhunting and habitat destruction, the Canada Goose has rebounded to become one of North America’s most abundant and familiar wildfowl.

Brent Goose

A small goose species with a short, stubby bill, the brent goose (or brant, as it is known in North America), breeds in the high Arctic regions of Canada, Greenland, Siberian Russia and northern Europe’s Arctic islands. Brant spend winters along North America’s Pacific coast, part of the east coast of the US, and in north-western Europe, from the British Isles to Denmark.

Bewick's Swan

A subspecies of the North American tundra swan, Bewick’s swans breed in Siberia and arrive in the UK each autumn. Worrying declines have been observed in the European population in recent years, and today only around 4,350 individuals migrate to the UK each winter.

Barnacle Goose

A small and strikingly marked goose of the north, Barnacle Geese were once believed to grow from barnacles. We now know that these migratory wildfowl breed in the Arctic, often nesting on precipitous cliffs to protect their eggs from predators.

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