Thecommon merganser(North American) orgoosander(Eurasian) (Mergus merganser) is a largesea duckof rivers and lakes in forested areas of Europe, Asia, and North America. The common merganser eats mainly fish. It nests in holes in trees.
| Common merganser Temporal range:
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|---|---|
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| M. m. merganser,male inSandwell,England | |
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| M. m. americanus,female | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Anseriformes |
| Family: | Anatidae |
| Genus: | Mergus |
| Species: | M. merganser
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| Binomial name | |
| Mergus merganser | |
| Subspecies | |
|
3, seetext | |
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| M. merganserrange Breeding Resident Passage Non-breeding
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| Synonyms | |
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Merganser americanusCassin, 1852 | |
Taxonomy
editThe firstformal descriptionof the common merganser was by Swedish naturalistCarl Linnaeusin 1758 in the10th editionof hisSystema Naturae.He introduced the currentbinomial nameMergus merganser.[2]The genus name is aLatinword used byPlinyand otherRomanauthors to refer to an unspecified waterbird, andmerganseris derived frommergusandanser,Latin for "goose".[3]In 1843John James Audubonused the name "Buff-breasted Merganser" in addition to "goosander" in his bookThe Birds of America.[4]
The threesubspeciesdiffer in only minor detail:[5][6]
| Image | Subspecies | Description | Distribution |
|---|---|---|---|
 |
M. m. merganser–Linnaeus,1758 | Throughout northern Europe and northern Asiatic Russia. | |
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M. m. orientalis–Gould,1845(syn.M. m. comatus–Salvadori,1895) | Slightly larger thanM. m. merganser,it has a more slender bill. | Central Asian mountains. |
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M. m. americanus–Cassin,1852 | Its bill is broader-based than inM. m. merganser,and a black bar crosses the white inner wing (visible in flight) on males. | found in North America. |
Description
editIt is58–72 cm (23–28+1⁄2in) long with a78–97 cm (30+1⁄2–38 in) wingspan and a weight of 0.9–2.1 kg (2 lb 0 oz – 4 lb 10 oz); males average slightly larger than females, but with some overlap. Like otherspeciesin thegenusMergus,it has a crest of longer head feathers, but these usually lie smoothly rounded behind the head, not normally forming an erect crest. Adult males in breeding plumage are easily distinguished, the body white with a variable salmon-pink tinge, the head black with an iridescent green gloss, the rump and tail grey, and the wings largely white on the inner half, black on the outer half. Females and males in "eclipse" (non-breeding plumage, July to October) are largely grey, with a reddish-brown head, white chin, and white secondary feathers on the wing. Juveniles (both sexes) are similar to adult females but also show a short black-edged white stripe between the eye and bill. The bill and legs are red to brownish-red, brightest on adult males, dullest on juveniles.[5][6][7]
Behaviour
editFeeding
editLike the other mergansers, these piscivorous ducks have serrated edges to their bills to help them grip their prey, so they are often known as "sawbills". In addition to fish, they take a wide range of other aquatic prey, such asmolluscs,crustaceans,worms, insect larvae, and amphibians; more rarely, small mammals and birds may be taken.[5][6]As in other birds with the character, the salmon-pink tinge shown variably by males is probably diet-related, obtained from thecarotenoidpigments present in some crustaceans and fish.[8]When not diving for food, they are usually seen swimming on the water surface, or resting on rocks in midstream or hidden among riverbank vegetation, or (in winter) on the edge of floating ice.[5][6]
Habits
editIn most places, the common merganser is as much a frequenter of salt water as fresh water. In larger streams and rivers, they float down with the stream for a few miles, and either fly back again or more commonly fish their way back, diving incessantly the whole way. In smaller streams, they are present in pairs or smaller groups, and they float down, twisting round and round in the rapids, or fishing vigorously in a deep pool near the foot of a waterfall or rapid. When floating leisurely, they position themselves in water similar to ducks, but they also swim deep in water like cormorants, especially when swimming upstream. They often sit on a rock in the middle of the water, similar to cormorants, often half-opening their wings to the sun. To rise from water, they flap along the surface for many yards. Once they are airborne, their flight is strong and rapid.[9]They often fish in a group forming a semicircle and driving the fish into shallow water, where they are captured easily. Their ordinary voice is a low, harsh croak, but during the breeding season, males in display, as well as young, make a plaintive, soft whistle. Generally, they are wary, and one or more birds stay on sentry duty to warn the flock of approaching danger. When disturbed, they often disgorge food before moving.[10]Though they move clumsily on land, they resort to running when pressed, assuming a very upright position similar to penguins, and falling and stumbling frequently.[11]
Breeding
editNestingis normally in a tree cavity, so it requires mature forest as its breeding habitat; they also readily use large nest boxes where provided, requiring an entrance hole 15 cm (6 in) in diameter.[12]In places devoid of trees (like Central Asian mountains), they use holes in cliffs and steep, high banks, sometimes at considerable distances from the water.[10]The female lays 6–17 (most often 8–12) white to yellowish eggs, and raises one brood in a season. The ducklings are taken by their mother on her back to rivers or lakes immediately after hatching, where they feed on freshwater invertebrates and small fish fry, fledging when 60–70 days old. The young are sexually mature at the age of two years.[5][6][7]Common mergansers are known to formcrèches,with single females having been observed with over 70 ducklings at one time.[13]
Movements
editThe species is a partialmigrant,with birds moving away from areas where rivers and major lakes freeze in the winter, but resident where waters remain open. Eastern North American birds move south in small groups to the United States wherever ice-free conditions exist on lakes and rivers; on the milder Pacific coast, they are permanent residents.ScandinavianandRussianbirds also migrate southwards, but western European birds, and a few inJapan,are largely resident.[5][6]In some populations, the males also show distinct moult migration, leaving the breeding areas as soon as the young hatch to spend the summer (June to September) elsewhere. Notably, most of the western European male population migrates north to estuaries inFinnmarkin northernNorway(principallyTanafjord) to moult, leaving the females to care for the ducklings. Much smaller numbers of males also use estuaries in easternScotlandas a moulting area.[7][14][15]
Status and conservation
editOverall, the species is not threatened, though illegal persecution by game-fishing interests is a problem in some areas.[16]In February 2020, a rare common merganser sighting was documented inCentral Park, New York;the bird was in obvious distress, with its beak being trapped by a piece of debris.[17]
Within western Europe, a marked southward spread has occurred fromScandinaviain the breeding range since about 1850, colonisingScotlandin 1871,Englandin 1941, and also a strong increase in the population in theAlps.[7]They are very scarce inIreland,with regular breeding confined to a few pairs inCounty Wicklow.[18]
The goosander is one of the species to which theAgreement on the Conservation of African-Eurasian Migratory Waterbirdsapplies.
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Mergus mergansercouple,Vaxholm, Sweden -
Female goosander's bill showing the serrated edge -
Couple and single female on theJonain Switzerland -
M. m. americanus,female and juveniles -
Egg, CollectionMuseum Wiesbaden -
Robert Wilkinson Padley -A Goosander,1817 -
In flight atKoshi Tappu Wildlife Reserve,Nepal. -
A flock resting inYstad2024.
References
edit- ^BirdLife International (2018)."Mergus merganser".IUCN Red List of Threatened Species.2018:e.T22680492A132054083.doi:10.2305/IUCN.UK.2018-2.RLTS.T22680492A132054083.en.Retrieved13 November2021.
- ^Linnaeus, C.(1758).Systema Naturæ per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Volume 1(in Latin). Vol. v.1 (10th ed.). Holmiae:Laurentii Salvii. p. 129.
- ^Jobling, James A (2010).The Helm Dictionary of Scientific Bird Names.London: Christopher Helm. pp.250–251.ISBN978-1-4081-2501-4.
- ^Audubon, J.J. (1843).The birds of America.Vol. 6. pp. 387–394.
- ^abcdefdel Hoyo, J.; Elliott, A.; Sargatal, J., eds. (1992).Handbook of the Birds of the World.Vol. 1. Barcelona: Lynx Edicions. p.626.ISBN978-84-87334-10-8.
- ^abcdefMadge, S.; Burn, H. (1987).Wildfowl: An Identification Guide to the Ducks, Geese and Swans of the World.A & C Black.ISBN978-0-7470-2201-5.
- ^abcdSnow, D.W.; Perrins, C.M. (1998).The Birds of the Western Palearctic(Concise ed.). Oxford: Oxford University Press.ISBN978-0-19-854099-1.
- ^Hudon, J.; Brush, A.H. (1990)."Carotenoids produce flush in the Elegant Tern plumage"(PDF).The Condor.92(3): 798–801.doi:10.2307/1368708.JSTOR1368708.
- ^Hume, A.O.; Marshall, C.H.T. (1880).The Game birds of India, Burmah and Ceylon.Vol. 3. Self published.
- ^abBaker, E.C.S. (1928).Fauna of British India. Birds.Vol. 5 (2nd ed.). London: Taylor and Francis. pp. 470–473.
- ^Baker, E.C. Stuart (1922).The game birds of India, Burma and Ceylon.Vol. 1. London, Bombay Natural History Society. pp. 317–327.
- ^du Feu, C. (2005).Nestboxes(PDF).British Trust for Ornithology Field Guide. Thetford: The British Trust for Ornithology.
- ^Mervosh, Sarah (2018-07-24)."1 Hen, 76 Ducklings: What's the Deal With This Picture?".The New York Times.
- ^Little, B.; Furness, R.W. (1985)."Long distance moult migration by British GoosandersMergus merganser".Ringing & Migration.6(2): 77–82.doi:10.1080/03078698.1985.9673860.
- ^Hatton, P.L.; Marquiss, M. (2004)."The origins of moulting Goosanders on the Eden Estuary".Ringing & Migration.22(2): 70–74.doi:10.1080/03078698.2004.9674315.
- ^"Crimes against birds".Partnership for Action Against Wildlife Crime in Scotland.2009-12-07.
- ^Kilgannon, Corey (2020-02-24)."Central Park Races to Save a Rare Duck Gagging on a Piece of Plastic".The New York Times.ISSN0362-4331.Retrieved2020-02-26.
- ^Report of the Irish Rare Breeding Birds Panel 2013Irish BirdsVol. 10 p.65
External links
edit
- "Goosander media".Internet Bird Collection.
- Common Merganser photo galleryat VIREO (Drexel University)