From its continent-wide, boreal breeding distribution, the Red-breasted Merganser moves south to winter along all three coasts. Its late breeding season means that fall migration doesn’t take place until September or October when the young are able to fly. Red-breasted Mergansers migrate and winter in small flocks, and seldom mix with other species.
Red-breasted Mergansers do not breed until two years of age, and many females not until three years of age. By far the major cause of mortality in ducklings is exposure to harsh weather, although predation tales a toll as well. Red-breasted Mergansers are known to have lived up to nine years in the wild.
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Description of the Red-breasted Merganser
BREEDING MALE
The Red-breasted Merganser has a long, slender, orange bill and a shaggy crest.
Male/breeding plumage:?
– Dark green head.
– White collar.
– Streaked breast and gray-barred flanks.

Photograph © Glenn Bartley
Female
– Brownish head.
– Grayish-brown upperparts.
Seasonal change in appearance
Eclipse plumage males resemble females.
Juvenile
Juveniles resemble females.
Habitat
Lakes and coastal areas.
Diet
Fish.

Female. Photograph © Glenn Bartley
Behavior
Forages by diving.
Range
Breeds from Alaska to eastern Canada and Greenland and winters along both coasts and on inland lakes. Also occurs in Russia, Europe, and Asia.
Fun Facts
The serrations on the Red-breasted Merganser’s bill led to its nickname of sawbill, and help it to grasp fish when foraging.
Red-breasted Mergansers do not defend territories, and sometimes nest colonially.
Vocalizations
A catlike meow or croaks are sometimes given during courtship.
Similar Species
- Common Merganser males have white flanks and breasts. Female Common Mergansers have a sharp line of demarcation between brown head and white breast.
Nesting
The nest is a depression in a sheltered area.
Number: 7-10.
Color: Olive.
Incubation and fledging:
– Young hatch at 29-35 days.
– Young fledge (leave the nest) shortly after hatching.
Bent Life History of the Red-breasted Merganser
Published by the Smithsonian Institution between the 1920s and the 1950s, the Bent life history series of monographs provide an often colorful description of the birds of North America. Arthur Cleveland Bent was the lead author for the series. The Bent series is a great resource and often includes quotes from early American Ornithologists, including Audubon, Townsend, Wilson, Sutton and many others.
Bent Life History for the Red-breasted Merganser – the common name and sub-species reflect the nomenclature in use at the time the description was written.
MERGUS SERRATOR Linnaeus
The red-breasted merganser, or sheldrake, as it is commonly called in New England, the “bec-scie” or “saw bill” of the Acadians, although often hunted, is generally classed as a fish duck and considered almost worthless. But there are other things in life besides bread and meat and dollars and cents, and the esthetic appreciation of this, as well as of many other “worthless” birds, is surely increasing.
The drake in his newly acquired nuptial plumage is resplendent with a metallic green headdress and waving crest, the whole set of by a long coral-red bill. The white ring about his neck, the reddish brown and speckled breast, the snowy flanks and wing patches, and the dark back all go to create a picture of great beauty as he swims or dives or restlessly flies to and fro among the breakers. The females and young in their more modest suits of drab and brown are not to be despised from an esthetic point of view. They, too, like the drakes, are furnished with crests.
The great multitudes of these birds off the New England coast in winter is a wonderful sight and most satisfying to the bird lover, especially as there seems to be no doubt that the numbers have in- creased of late years. This increase is doubtless due partly to the better enforcement of game laws and to the stopping of spring shooting, but also to the fact that the great island of Anticosti in the Gulf of St. Lawrence has become a veritable haven for breeding birds since M. Meunier, the French chocolate king, has debarred all guns from this, his domain. During the last of October and the first part of November for several miles off Ipswich Beach the water is covered with these birds, and I have no doubt that the multitude at times numbers 25,000.
Spring: The spring migration of this bird is at its height on the New England coast in March and April, but it also continues through May. Although it does not, as a rule, breed south of southern Maine, it is not uncommon to find two or three nonbreeding birds from place to place along the coast in summer as far south as Cape Cod.
Courtship: The courtship of the red-breasted merganser is a spectacular performance. I (1911) have described it as observed at Ipswich as follows:
The nuptial performance is always at its best when several drakes are displaying their charms of movement, voice, and plumage, before a single duck, and each vies with the other in the ardor of the courtship. The drake begins by stretching up his long neck so that the white ring is much broadened, and the metallic green head, with its long crest and its narrow red bill, makes a conspicuous object. At once the bill i5 opened wide and the whole bird stiffly bobs or teeters, as if on a pivot, in such a way the breast and the lower part of the neck are immersed, while the tail and posterior part of the body swing upward. This motion brings the neck and head from a ver- tical position to an angle of 450 All the motions are stiffly executed, and suggest a formal but ungraceful courtesy.
This song, emitted when the bill is opened, is a difficult one to describe, but easily recognized when once heard, and remains long in the memory after one has heard it repeated over and over again by a number of merganser suitors. It is a loud, rough, and purring, slightly double note which I wrote down ‘da-ah,” but the note is probably insusceptible of expression by syllables. The bobbing and the love note may be given twice in rapid succession, although at times the performance is a single one, or may consist of an extensive bob, preceded by a slighter but similar one. The performance is, however, repeated at frequent or infrequent intervals, depending on the ardor and number of the suitors, and, no doubt, on the attitude of the modestly dressed lady. Although the female merganser may remain passive and coyly indifferent, as is the habit of her sex, she sometimes responds by a bobbing which is similar to that of the male, but of considerably less range. That is to say, the neck is not stretched so straight up, and the breast is not so much depressed during the bob. She emits a single note at this time, which is somewhat louder than that of the male and is of a different quality as it is decidedly rasping. As nearly as I can remember this note is similar to the rough croaks I have heard given by these birds in Labrador wli~i they were flying. to and from their nests. When the female responds in this manner she appears to be very excited, and the ardor of the drakes is correspondingly increased, if one may judge by the frequent repetition of the love antics and notes, and by the fact that they crowd about the duck. Every now and then she darts out her neck and dashes at the ring of suitors, just as the female English sparrow does under similar circumstances. The bobbing Up of the stern of the male is the more conspicuous as the wings are then apparently slightly arched upwards, so that the white secondary feathers are very prominent. These show at all times as the male swims in the water, but in the female they are generally, but not always, invisible.
The drakes, in their eagerness, often rush through the water with slightly opened wings making the water foam about them. Again they rise in the water with wings close to the side until they almost seem to stand on tip-toe.
Nesting: The nest of the red-breasted mergansor is built on the ground, and, although the bird is marine in its haunts, the nest is generally situated in the borders of fresh-water ponds, pools, or rivers, often, however, in close proximity to the seacoast. Occasionally it is found on the shore of the ocean itself or on coastal islands. The bird also breeds throughout the interior at long distances from the sea. According to Macoun (1909) “it does not breed in the prairie region, but prefers the clear lakes and streams of the north.” The nest is generally built within 25 yards of the water.
The nest, although sometimes built in the open, is generally placed under some shelter, as the overhanging and prostrate branches of dwarfed spruces, firs, or willows, or among the roots of trees or in a pile of driftwood, and is so well concealed and the female lies so close that the intruder often nearly steps into the nest before he is aware of its presence. Macfarlane (1908) mentions a nest near the Ander- son River “on the border of the ‘Barrens’ to the east, under a fallen tree, close to a small lake. It was a scooped-out hole lined with feathers and down, and it contained six eggs.” [Author’s note: The red-breasted merganser breeds abundantly in the Magdalen Islands, Quebec, where numerous nests have been found by others, as well as by me. An island near Grosse Isle, known as Seal Island, is a famous breeding resort for this species. It is a high island of red sandstone, nearly covered with a dense forest of spruces and firs, under which the nests are concealed. A typical nest, shown in the accompanying photograph, was located in the thick woods, about 1 rod from the edge and about 40 yards from the shore; it was perfectly concealed under a dense thicket of balsam firs and would never have been discovered except that we saw the bird fly out and a few pieces of down indicated where to look. The nest was a hollow in the ground, profusely lined with gray down and a few white breast feathers; it measured 14 by 12 inches in outside and 8 by 7 inches in inside diameter. Several pieces of dry egg membrane in the nest suggested the idea that it might have been used the previous season also. It contained eight fresh eggs on June 21, 1904.
On the previous day we had found a nest of this species in a very different situation, on what is locally known as the Gully Flats, a long stretch of beaches and sand dunes with numerous marshy or grassy hollows scattered among the sand hills. The nest was in one of these small marshy hollows, which was overgrown with coarse sedges or marsh grasses; it was well concealed in the thickest grass and was made of the dry stalks of this grass, scantly arranged under, around, and partially over the eggs; very little down had been added, as the six eggs were perfectly fresh and the set was probably incom- plete.
The down in the nest of the red-breasted is much darker than that found in the nest of the American merganser; it is “mouse gray” with paler centers and usually pure white breast feathers and more or less rubbish are mixed with it. When the set is complete ~ thick blanket of down and rubbish is provided in sufficient quantity to entirely conceal the eggs when the bird has time to cover them before leaving the nest.
Eggs: This merganser usually lays from 8 to 10 eggs, sometimes as many as 16. The eggs are quite different from those of the Ameri- can merganser. The shape varies from elliptical ovate or elliptical oval to elongate ovate. r[he shell is smooth but without much luster. The color varies from a rich “olive buff” or “pale olive buff” to “cartridge buff”; the olive shades are commoner than the lighter shades. The measurements of 85 eggs in t.he United States National Museum average 64.5 by 45 millimeters; the eggs showing tile four extremes measure 67.5 by 46, 67 by 46.5, 56.5 by 43 and 60.5 by 41 millimeters.]
Young: Incubation lasts from 26 to 28 days and is performed entirely by the female; the drakes are rarely seen in the neighborhood during this period. P. L. Hatch (1892), who has found this bird breeding within a few miles of both Minneapolis and St. Paul, says: Only a very few individuals have seen these ducks during the summer, for the obvious reason that, like all other locally breeding ducks, they are rarely found on the wing.
The young are active within a few hours of hatching, as has been well described by R. M. Strong (1912), and wriggle in a prostrate manner over the ground like a snake. They are soon able to run about on their feet and climb easily to the mother’s back.
The food of the young consists of small fish, water insects and larvae, worms, crustaceans, and sometimes frogs. Both parents are assiduous in caring for the young. The young mergansers are care- fully fed and guarded by their parents, and the family group keeps together until the young are fully grown. At the slightest sign of danger the young conceal themselves under the bushes and among the reeds of the banks of the river or pond, while the adults do their best to entice the intruder away. When suddently disturbed in the open the young are able to make their way over the surface of the water with surprising rapidity by the combined action of the wings and legs. The noise of such a flight often confuses the enemy. On open shores I have known the young to flee from the approaching canoe, creep ashore, and, trusting to their protecting coloring, crouch motionless among the rocks and small plants.
Rev. Manley B. Townsend contributes the following pretty picture of a family party:
One summer day, toward evening, as I sat upon the shore of a wilderness lake drinking in the beauty of the forest and the mountain, a flock of red-breasted mer- gansers came sailing around a rocky point, close inshore. There were 10, led by a wary old male in full adult plumage. The other nine were much duller of color. I took them for the mother and her eight children. How alert! How wary! How incomparably wild! Suspiciously they scanned me, but I sat immovable. Plainly they were nonplussed. Yet they were taking no chances. Silently they submerged until only their heads and upper necks were ahove the surface, and turning swam quietly off out into the lake. A calculated movement on my part, and off went the whole family, led by the father, leaving a foamy wake to mark their tumultuous passage.
Plumages: AUTHOR’S NOTE: The downy young red-breasted mer- ganser is exactly like the young American merganser except for two very slight differences in the head; the nostrils in the red-breasted are in the basal third of the bill, whereas in the American they are in the central third; and the white loral stripe is tinged with brownish or fluffy but with a more or less distinct white spot under the eye.
The down is worn for a long time. The first of tile plumage appears on the under parts, then comes the tail, the flanks, and the scapulars in the order named; the remainder of the body plumage follows, then that of the head and neck; the wings appear last, and the bird is fully grown before it can fly. The last of the down is on the hind neck or central back.
Millais (1913) says that in its first plumage the young male: resembles the adult female, but the crest is less, the bill much shorter, and the plum- age of the upper parts more slaty and not nearly so brown, and the cheeks more red with less white. The ends of the tail are also worn. By the end of October young males are easily recognized by their superior size and bill. It is not until December that much change takes place. The red-brown crest is then abundant, and black feathers begin to appear on the sides of the crown and cheeks, chin, mantle, and scapulars. The tail and rump also begin to molt to blue gray, and many vermicu- lated feathers mixed with slaty-brown ones come in on the thighs and flanks. By the end of March some white feathers appear on the scapulars and the first white, broadly black-edged feathers come in on the sides of the breast overlapping the wings. These prominent feathers are, however, never complete as in the case of the adult males, but are always divided in color, the lower halves being red and vermiculated with black from the broad black edge to the white above. The nape is now very dark-brown edged with worn blue gray, and not a clear rich red brown, as in the female. The long inner secondaries, similar to adult males, now also appear.
I have seen young males in this plumage, with immature backs and wings, and with more or less black mottling in the heads and necks, in March, April, May, and June, during which time the aM males are, of course, in full nuptial plumage.
Millais (1913) says: The young male during May and June molts all signs of the brilliant spring plum- age. and passes into an eclipse similar to the adult male. It can, however, always be identified by the immature wing, which is brown and slate on all its upper parts, instead of being black with a large white area in the center, as in the adult male. During August, September, and October the general molt toward complete winter plumage is in progress, and the young male does not come into full dress until the end of November. It may then be considered adult at 17 months.
The fully adult plumage is worn during the winter and spring until the molt into the eclipse begins; this sometimes begins in March and proceeds very slowly, but more often it does not begin until late spring or early summer; it is complcte in August. Millais (1913) thus describcs a specimen in full eclipse plumage taken on August 20:
Head, neck, and upper breast almost exactly similar to adult female, but with only a very short area of white on the chin; mantle and scapulars blackish brown, edged with gray; wings, which have just been renewed, as in winter; rump and lower back a mixture, brownish ash-gray feathers like the female, and white vermicu- fated with black (as in spring); flanks and sides of the chest brownish gray like the female. There are a few slate and brown vermiculated feathers at the sides of the vent. Under parts white, and soft parts as in spring, only not so bright.
The molt of the eclipse plumage begins, early in September and continues through October and Novembcr, or with some individuals much longer; I have a specimen in my collection, taken November 7, in which this molt is only fairly started; by January at the latest most of the males are in full plumage again.
Of the immature females Millais (1913) says: in first plumage the young female is similar to the adult female, except for the less abundant crest and small area of black round the eye. Tail feathers are worn and wing markings less distinct. The scapular and mantle feathers, too, which remain unchanged until March are like nearly all immature female ducks pale and worn on their outer edges and generally gray or sandy and unlike the clean rich feathers of adults. By April it is difficult to distinguish between immature and adult females, except that the young never possess the large area of black round the eye nor the black feathers at the sides of the chin, and only the throat. The wings are as usual the main character in distinguishing age. I do not think these young birds breed nor are they adult until the following November.]
Food: The red-breasted anerganser is chiefly a fish eater, but it does not disdain to gather up crustaceans and mollusks. In fresh water it is fond of crawfish. Its long serrated bill with the teeth pointing backward is well adapted to holding its slippery prey. Nelson (1887) remarks that it feeds oil sticklebacks, which abound in the brackish ponds of Alaska. It delights in the rapids of livers, in tidal estuaries, and in the shallow places off sand beaches and at the mouth of rivers, where small fish most do congregate. Strenuous must be the life of the small fry in these regions when a large flock of mergansers are diving together.
Behavior: The flight of the shelldrake is lacking in the initial power shown by the black duck. Unlike the latter bird, it can not spring straight up into the air. Rising from the water or ground is indeed always a laborious process, but especially so in calm weather, when there is no wind to oppose its airplanes. There is a noisy flap- ping of the wings and a strenuous pushing away of the water or sand with the feet for some distance before the surface can be cleared. A pair that I disturbed from the beach on a calm day showed the marks of their feet for 29 yards before they succeeded in getting away from the sand. Once on the wing their flight, is noiselcss and is generally close to the, water, differing in this way from that of the golden eye which frequents the same shores, but which usually rises to a considerable height. When flying in j)airs in the sJ)ring, the fe- male generally precedes. it is a rapid swimmer and perfectly at home in the roughest water. As a diver the bird is truly an expert, and it disappears under water with wings close to its sides, making use of its powerful feet alone except on rare occasions when its wings are also brought into play. At times it leaps clear of the surface, describes a graceful arc and enters the water like a curved arrow, while at other times it disappears with scarcely a sign of effort. It often swims with its head and neck stretched out in front, as if it were skimming the water and straining it with its serrated bill for food. Again it advances with the head, all but the crest, below the surface apparently on the lookout for fish, and, at such times, it is con- antly diving. At the moment of diving the crest is flattened down: when the birds swim beCore a strong wind the crests often blow up and over the head.
On the land the red-breasted merganser is an awkward walker. It often rests flat on its belly or stands up with its body at an angle of 45O~ Again, it stands with its body parallel with the ground like an ordinary duck.
The courtship note, or love song. has already been described. This may be heard not only in the spring but occasionally also in the autumn, as in the case of so many, if not all, birds, a ohenomenon known as the “autumnal recrudescence of the amatory instinct.” The rough croak of the female at this time has also been mentioned. A similar rough croak is emitted by these birds (luring the breeding season; I have heard it as they flew back and forth from their nests. and once on a small stream in Labrador, in early August, a female flew close to the water ahead of the canoe croaking hoarsely. She probably wished to entice me away from her young, which may have been concealed under the bushes.
Game: Although very “fishy eating’ the red-breasted merganser is assiduously hunted along the New England coast. It is a shy bird but comes in well to wooden decoys anchored off points, along the shore or in tidal estuaries. The gunner takes his station near at hand in a blind made of brush or sea weed or sometimes of ice cakes, and is most successful in the early morning when the birds are com- ing in from their night’s rest on the ocean. Gunning punts covered with marsh grass are also used, but one must be a skillful sculler to be able to approach within gunshot of the wary birds. Birds that are merely winged are almost impossible to recover, as they are won- derful divers and generally elude pursuit. They often swim away with only the bill above water.
Winter: In the latter part of September in Kcw England, the species begins to arrive from the north and becomes exceedingly numerous during October and November. In December the numbers diminish, but it is one of our most abundant waterfowl on the Mass- achusetts coast throughout the winter. Tn the spring migration of March and April the numbers increase, but it is not until the last of May, or even the first of June that they have all left for the north. But the story of the migration of this bird is not so simple as the above statement would imply, for there is a sexual as well as an age difference to be considered. The large flocks in the early fall appear to be all in brown dress, and this is the dress not only of the females and young but also of the adult males, who are then in the eclipse plumage. In November this l)lumage is molted, and the males appear resplendent in their courtship dress, while the females and young of both sexes leave for the south, so that during the winter months the vast majority are in full male plumage. rfhus, one January day, out of 500 sheidrakes off Ipswich Beach I could count only 6 in the dull plumage. Whether these were adult females or young or both I cannot say. In March the females put in an appear- ance and courting begins, and by the last of April and in May the birds are largely paired, although flocks of either or both sexes are common as well as those of immature males who have not molted into full plumage are common. Some at least of the immature males are slow in changing to adult plumage, and males in nearly complete immature dress with only a few greenish feathers about the head are often to be found in April and May. On the other hand, I have seen a bird that was half molted int.o adult male plumage as early as the 16th of February; this was probably an adult changing from the eclipse plumage, the others immature birds.
The southern side of this picture, which rounds out and corrobo- rates my northern observations has been given me by Mr. William Brewster, who says that in Florida, in winter, he has seen large flocks of female and immature red-breasted mergansers, and by Mr. Arthur T. Wayne (1910) who, says of this species:
From the time when these fish-eating ducks arrive until the first week in February, the adult drakes are seldom, if ever, seen, hut toward the second week in February they make their appearance in large numbers.
It would seem, therefore, that some of the drakes go south to escort their partners back to the breeding home.
On the New England coast in winter this bird is to be found in largest numbers off the beaches and in the coves and harbors, it frequents also the tidal estuaries among the salt marshes into which it enters at dawn and from which it flies at sunset in order to sleep with more safety on the ocean; in this respect its habits are the oppo- site of those of the black duck. It is evident that the merganser is not as common of late years in tidal estuaries, as it is more apt to be disturbed by gunners and motor boats. It occasionally visits the fresh-water ponds and rivers during the migrations along the sea coast, but does not prefer them to salt water, as does its cousin the goosander. Its habits during the winter have been described above. Courting takes place all along the New England coast even that part far from the breeding range, and begins in good weather as early as February.
The long neck, head, and bill of the sheidrake, its flat body, ‘and conspicuous white-marked wing makes its recognition in the air usu- ally an easy one. The adult drake is easily distinguished by its red- dish breast and by its crest from the goosander; the females and young can often be distinguished, even at a distance, from the very similar females and young of the goosander by the more c]early defined white throat of the latter bird. In the red-breasted species the white is less in extent and shades gradually into the brown of the neck. This is an important field mark and is often overlooked, for most authorities write that the female and young of these two species can only be distinguished in the hand by the position of the nostril, which is in the middle of the bill in the case of the goosander and nearer the base in the red-breasted species. The back of the female goosander is of pearl-blue color while that of the red-breasted species is (lark ashy with a brownish tinge. These differences are also noticeable in the field.
DISTRIBUTION
Breeding range: Northern portions of the Northern Hemisphere. In North America, south to Newfoundland, Nova Scotia (Kings County), New Brunswick (Grand Manan), coast of Maine (Jericho Bay), northern New York (Adirondacks), southern Ontario (Parry Sound), central Michigan and Wisconsin (Green Bay), central Min- nesota (near St. Paul), southern Manitoba (Lake Manitoba), central Alberta (Buffalo Lake), southeastern British Columbia (Columbia River), southern Alaska (Chichagof Island), and the Aleutian Islands. North to t.he Arctic coast of Alaska (Icy Cape), Mackenzie (Fort Anderson), southern Baflin Land (Cumberland Sound) and central Greenland (ITp6rnivik and Scoresby Sound). In the Eastern Hemisphere, the breeding range includes Lecland, Ireland, Scotland, Scandinavia, northern Russia, northern Siberia, and the Kurile islands.
Winter range: Mainly on the coasts of the United States. On the Atlantic coast from Maine to Florida, on the Gulf coast from Florida to ‘rexas. On the Pacific coast from British Columbia to Lower California (La Paz). In the interior from the Great Lakes south- ward. In the Eastern Hemisphere it is generally distributed over Europe, the Mediterranean, north Africa, the Black and Caspian Seas, Persia, northwest India, China and Japan.
Spring migration: Average dates of arrival: Quebec, Montreal, April 16 (earliest April 6); Prince Eward Island, North Rivcr, Xpril 21 (earliest. April 15); Ungava, Lake Mistassini, May ii; Minnesota, Heron Lake, April 3: Manitoba, Aweme, April 22: Alaska, Chilcat, May 8, St. Michael, May 24, atid Kowak River, middle of June. Late dates of departure: Missouri, Kansas City, May 4: Ohio, Ober- lin, May 22; Pennsylvania, Erie, May 30; Rhode Island, Newport, May 16; Massachusetts, Essex County, May 20: California, Monterey, May 25.
Fall migration: Early dates of arrival: Massachusetts, l~ssex County, September 23; Pennsylvania, Erie, September 6; California, Monterey, October 9. Late dates of departure: Mackenzie River, latitude 63~, October 16: Quebec, Montreal, November 1.
Casual records: –Accidental in Cuba t I-iabaiia, December, 1891), Bermuda, and Hawaiian Islands.
Egg dates: –Labrador: Fourteen records, June 4 to July 16; seven records, June 26 to July 7. Magdalen Islands: Eleven records, June 17 to 26. Alaska: Five records, June 26 to July 9. iceland: Five records, May 20 to June 23.