Editing Common merganser

{{Short description|Species of bird}}
{{Speciesbox
| name = Common merganser
| fossil_range = {{Fossil range|Pleistocene|present}}
| status = LC

| status_system = IUCN3.1
| status_ref = <ref name="iucn status 13 November 2021">{{cite iucn |author=BirdLife International |date=2018 |title=''Mergus merganser'' |volume=2018 |page=e.T22680492A132054083 |doi=10.2305/IUCN.UK.2018-2.RLTS.T22680492A132054083.en |access-date=13 November 2021}}</ref>
| image = Mergus merganser -Sandwell -England -male-8.jpg
| image_caption = ''M. m. merganser'', male in [[Sandwell]], England
| image2 = Female Mergus merganser americanus at Las Gallinas Wildlife Ponds.jpg
| image2_caption = ''M. m. americanus'', female
| genus = Mergus
| species = merganser
| authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| range_map = MergusMerganserIUCNver2019-2.png
| range_map_caption = ''M. merganser'' range {{leftlegend|#00FF00|Breeding|outline=gray}} {{leftlegend|#008000|Resident|outline=gray}} {{leftlegend|#00FFFF|Passage|outline=gray}} {{leftlegend|#007FFF|Non-breeding|outline=gray}}
| synonyms = ''Merganser americanus'' Cassin, 1852
| subdivision_ranks = Subspecies
| subdivision = 3, see [[#Taxonomy|text]]
}}

The '''common merganser''' (North American) or '''goosander''' (Eurasian) ('''''Mergus merganser''''') is a large [[Mergini|sea duck]] of rivers and lakes in forested areas of Europe, Asia, and North America. The common merganser eats mainly fish.  It nests in holes in trees.

==Taxonomy==
The first [[Species description|formal description]] of the common merganser was written by Swedish naturalist [[Carl Linnaeus]] in 1758 in the [[10th edition of Systema Naturae|10th edition]] of his ''[[Systema Naturae]]''. He introduced the current [[binomial nomenclature|binomial name]] ''Mergus merganser''.<ref>{{cite book | last=Linnaeus | first=C. | author-link=Carl Linnaeus | year=1758 | title= Systema Naturæ per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Volume 1| volume=v.1 | edition=10th | page=129 | publisher=Holmiae:Laurentii Salvii  | language=la | url= https://www.biodiversitylibrary.org/page/727034 }}</ref>  The genus name is a [[Latin]] word used by [[Pliny the Elder|Pliny]] and other [[Ancient Rome|Roman]] authors to refer to an unspecified waterbird, and ''merganser'' is derived from ''mergus'' and ''anser'', Latin for "goose".<ref name= job90>{{cite book | last= Jobling | first= James A | year= 2010| title= The Helm Dictionary of Scientific Bird Names | url= https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling | publisher = Christopher Helm | location = London | isbn = 978-1-4081-2501-4 |pages =[https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling/page/n250 250]&ndash;251}}</ref> In 1843 [[John James Audubon]] used the name "Buff-breasted Merganser" in addition to "goosander" in his book ''[[The Birds of America]]''.<ref name=Audubon/>

The three [[subspecies]] differ in only minor detail:<ref name=Hoyo/><ref name=Madge/>
{| class="wikitable"
|-
! Image !! Subspecies!!  Description !! Distribution
|-
|[[File:Mergus merganser EM1B8635 (49757930576).jpg|120px]] ||''M. m. merganser'' – <small>[[Carl Linnaeus|Linnaeus]], 1758</small> || ||Throughout northern Europe and northern Asiatic Russia.
|-
|[[File:Common Merganser (Mergus merganser) (46323801944).jpg|120px]]|| ''M. m. orientalis'' – <small>[[John Gould|Gould]], 1845</small> (syn. ''M. m. comatus'' – <small>[[Tommaso Salvadori|Salvadori]], 1895</small>) || Slightly larger than ''M. m. merganser'', it has a more slender bill.||  Central Asian mountains. 
|-
|[[File:062 - COMMON MERGANSER (1-5-13) patagonia lake, scc, az (1) (8717954203).jpg|120px]]|| ''M. m. americanus'' – <small>[[John Cassin|Cassin]], 1852</small> || Its bill is broader-based than in ''M. m. merganser'', and a black bar crosses the white inner wing (visible in flight) on males. ||found in North America. 
|-
|}

==Description==
It is {{convert|58|-|72|cm|in|frac=2|abbr=on}} long with a {{convert|78|-|97|cm|in|frac=2|abbr=on}} wingspan and a weight of {{convert|0.9|–|2.1|kg|lboz|abbr=on}}; males are on average slightly larger than females, but with some overlap. Like other [[species]] in the [[genus]] ''[[Mergus]]'', it has a crest of longer head feathers, but these usually lie smoothly rounded behind the head and do not normally form 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 sheen, 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.<ref name=Hoyo/><ref name=Madge/><ref name=Snow/>

==Behaviour==

===Feeding===
As with 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 as [[mollusc]]s, [[crustacean]]s, worms, insect larvae, and amphibians; more rarely, small mammals and birds may be taken.<ref name=Hoyo/><ref name=Madge/> As in other birds with this trait, the salmon-pink colouration shown variably by males is probably dietary-derived from the [[carotenoid]] pigments found in some crustaceans and fish.<ref name=Hudon1990/> When not diving for food, they are usually observed swimming on the surface of the water or resting on rocks in the middle of rivers or hidden in the vegetation along riverbanks, or (in winter) on the edge of floating ice.<ref name=Hoyo/><ref name=Madge/>

===Habits===
In most places, the common merganser is equally at home in salt and fresh water. In larger streams and rivers, they float down with the current for a few miles and either fly back or, more commonly, fish their way back, diving all the 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 at the foot of a waterfall or rapid. When swimming leisurely, they position themselves in the water much like dabbling ducks, but they also swim deep in the water like cormorants, especially when swimming upstream. They often sit on a rock in the middle of the water, similar to cormorants, often with their wings half-open to the sun. To rise from the water, they flap along the surface for many yards. Once they are airborne, their flight is strong and fast.<ref name=Hume1880/> 

They often fish in a group forming a semicircle and driving the fish into shallow water, where they are easy to catch. Their normal vocalisation is a low, harsh croak, but during the breeding season, males and juveniles produce a plaintive, soft whistle. They are generally wary, and one or more birds will remain on sentry duty to warn the flock of approaching danger. If disturbed, they will often disgorge food before moving.<ref name=fbi6/> Although they move clumsily on land, they resort to running when pushed to do so, assuming a very upright position similar to penguins, and frequently falling and stumbling.<ref name=Baker1922/>

===Breeding===
[[Bird nest|Nesting]] is usually in a tree cavity, so the species requires mature forest as its breeding habitat; they also readily use large nest boxes where these are available, requiring an entrance hole {{convert|15|cm|in|frac=2|abbr=on}} in diameter.<ref name=duFeu2005/> In treeless areas such as the mountains of Central Asia, they use holes in cliffs and steep, high banks, sometimes a considerable distances from the water.<ref name=fbi6/> The female lays 6–17 (most often 8–12) white to yellowish eggs, and raises one brood per season. The ducklings are carried by the mother on her back to rivers or lakes immediately after hatching, where they feed on freshwater invertebrates and small fish fry, fledging at 60–70 days of age. The young are sexually mature at two years of age.<ref name=Hoyo/><ref name=Madge/><ref name=Snow/> Common mergansers are known to form [[Crèche (zoology)|crèches]], with single females having been observed with over 70 ducklings at one time. <ref name=Mervosh2018/>

===Movements===
The species is a partial [[bird migration|migrant]], with birds moving away from areas where rivers and large lakes freeze in the winter, but resident where waters remain open. Birds from Eastern North America migrate south in small groups to the United States wherever lakes and rivers are ice-free; on the milder Pacific coast, they are permanent residents. [[Scandinavia]]n and [[Russia]]n birds also migrate southwards, but western European birds, and a few in [[Japan]], are largely resident.<ref name=Hoyo/><ref name=Madge/> In some populations, the males also show distinct moult migration, leaving the breeding grounds as soon as the young hatch to spend the summer (June to September) elsewhere. In particular, most of the Western European male population migrates north to estuaries in [[Finnmark]] in northern [[Norway]] (principally [[Tanafjord]]) to moult, leaving the females to care for the ducklings. Much smaller numbers of males also use estuaries in eastern [[Scotland]] as a moulting area.<ref name=Snow/><ref name=Little1985/><ref name=Hatton2004/>

==Status and conservation==
Overall, the species is not threatened, although illegal persecution by game-fishing interests is a problem in certain regions.<ref name=crime/> In February 2020, a rare common merganser sighting was documented in [[Central Park|Central Park, New York]]; the bird showed clear signs of distress, with its beak caught in a piece of debris.<ref>{{Cite news|last=Kilgannon|first=Corey|url=https://www.nytimes.com/2020/02/24/nyregion/central-parks-duck-plastic.html|title=Central Park Races to Save a Rare Duck Gagging on a Piece of Plastic|date=2020-02-24|work=The New York Times|access-date=2020-02-26|language=en-US|issn=0362-4331}}</ref>

Within Western Europe, there has been a marked southward expansion of the breeding range from [[Scandinavia]] in the breeding range since about 1850, colonising [[Scotland]] in 1871, [[England]] in 1941, and also a strong increase in the population in the [[Alps]].<ref name=Snow/> They are very rare in [[Ireland]], with regular breeding restricted to a few pairs in [[County Wicklow]].<ref>Report of the Irish Rare Breeding Birds Panel 2013  ''Irish Birds'' Vol. 10 p.65</ref>

The goosander is one of the species covered by the [[AEWA|Agreement on the Conservation of African-Eurasian Migratory Waterbirds]].

{{Gallery
  |title=Images
  |align=center
  |File:Mergus merganser, female and male, Vaxholm, Sweden.jpg
        |''Mergus merganser'' couple, [[Vaxholm, Sweden]]
  |File:Goosander looking up.jpg
        |Female goosander's bill showing the serrated edge
  |File:Jona - Jona (SG) - Mergus merganser IMG 9145.JPG
        |Couple and single female on the [[Jona (river)|Jona]] in Switzerland
  |File:Common Merganser, female and 4 young.jpg
        |''M. m. americanus'', female and juveniles
  |File:Mergus merganser MWNH 2015.JPG
        |Egg, Collection [[Museum Wiesbaden]]
  |File:Robert Wilkinson Padley - A Dun Diver (Goosander) - Google Art Project.jpg
        |Robert Wilkinson Padley - ''A Goosander'', 1817
    |File:Common merganser (Mergus merganser) 2024 (2).jpg
        |In flight at [[Koshi Tappu Wildlife Reserve]], [[Nepal]].
    |File:Storskrake (Mergus merganser) - Ystad-2024.jpg|A flock resting in [[Ystad]] 2024.
}}

==References==
{{Reflist|refs=
<ref name=Audubon>{{cite book |url=https://books.google.com/books?id=X4RIAAAAYAAJ&pg=PA387 |pages=387–394 |first=J.J. |last=Audubon |year=1843 |title=The birds of America |volume=6}}</ref>

<ref name=Baker1922>{{cite book |url=https://archive.org/stream/gamebirdsofindia01bake#page/n405/mode/2up |pages=317–327 |last=Baker |first=E.C. Stuart |year=1922 |title=The game birds of India, Burma and Ceylon |volume=1|publisher=London, Bombay Natural History Society }}</ref>

<ref name=crime>{{cite web |url=http://www.scotland.gov.uk/Topics/Environment/Wildlife-Habitats/paw-scotland/types-of-crime/crimes-against-birds |title=Crimes against birds |work=Partnership for Action Against Wildlife Crime in Scotland|date=2009-12-07 }}</ref>

<ref name=duFeu2005>{{cite book |last=du Feu |first=C. |year=2005 |title=Nestboxes |series=British Trust for Ornithology Field Guide |number=23 |url=http://www.bto.org/sites/default/files/u15/downloads/publications/guides/nestbox.pdf |location=Thetford |publisher=The British Trust for Ornithology}}</ref>

<ref name=fbi6>{{cite book |url=https://archive.org/stream/BakerFbiBirds6/BakerFBI6#page/n511/mode/1up |pages=470–473 |last=Baker |first=E.C.S. |year=1928 |publisher=Taylor and Francis |location=London |title=Fauna of British India. Birds |volume=5 |edition=2nd}}</ref>

<ref name=Hatton2004>{{cite journal |year=2004 |title=The origins of moulting Goosanders on the Eden Estuary |journal=Ringing & Migration |volume=22 |pages=70–74 |last1=Hatton |first1=P.L. |last2=Marquiss |first2=M. |doi=10.1080/03078698.2004.9674315 |issue=2 |doi-access=free }}</ref>

<ref name=Hoyo>{{cite book |editor1-last=del Hoyo |editor1-first=J. |editor2-last=Elliott |editor2-first=A. |editor3-last=Sargatal |editor3-first=J. |title=Handbook of the Birds of the World |volume=1 |publisher=Lynx Edicions |year=1992 |location=Barcelona |page=[https://archive.org/details/handbookofbirdso0001unse/page/626 626] |isbn=978-84-87334-10-8 |url=https://archive.org/details/handbookofbirdso0001unse/page/626 }}</ref>

<ref name=Hudon1990>{{cite journal |last1=Hudon |first1=J. |last2=Brush |first2=A.H. |year=1990 |title=Carotenoids produce flush in the Elegant Tern plumage |journal=The Condor |volume=92 |issue=3 |pages=798–801 |url=http://sora.unm.edu/sites/default/files/journals/condor/v092n03/p0798-p0801.pdf |doi=10.2307/1368708|jstor=1368708 }}</ref>

<ref name=Hume1880>{{cite book |url=https://archive.org/stream/GameBirdsOfIndia3/HumeGameBirds3#page/n331/mode/2up |year=1880 |title=The Game birds of India, Burmah and Ceylon |last1=Hume |first1=A.O. |last2=Marshall |first2=C.H.T. |volume=3 |publisher=Self published}}</ref>

<ref name=Little1985>{{cite journal |year=1985 |title=Long distance moult migration by British Goosanders ''Mergus merganser'' |journal=Ringing & Migration |volume=6 |pages=77–82 |last1=Little |first1=B. |last2=Furness |first2=R.W. |doi=10.1080/03078698.1985.9673860 |issue=2 |doi-access=free }}</ref>

<ref name=Madge>{{cite book |last1=Madge |first1=S. |last2=Burn |first2=H. |title=Wildfowl: An Identification Guide to the Ducks, Geese and Swans of the World |publisher=A & C Black |year=1987 |isbn=978-0-7470-2201-5}}</ref>

<ref name=Mervosh2018>{{cite news |url=https://www.nytimes.com/2018/07/24/science/merganser-ducklings-photo.html |title=1 Hen, 76 Ducklings: What's the Deal With This Picture?|newspaper=The New York Times|date=2018-07-24|last1=Mervosh|first1=Sarah}}</ref>

<ref name=Snow>{{cite book |title=The Birds of the Western Palearctic |last1=Snow |first1=D.W. |last2=Perrins |first2=C.M. |edition=Concise |year=1998 |publisher=Oxford University Press |location=Oxford |isbn=978-0-19-854099-1}}</ref>
}}

==External links==
{{Commons category|Mergus merganser}}
{{Wikispecies|Mergus merganser}}
* {{InternetBirdCollection|goosander-mergus-merganser|Goosander}}
* {{VIREO|common+merganser|Common Merganser}}

{{Taxonbar|from=Q180991}}
{{Authority control}}

[[Category:Mergansers|common merganser]]
[[Category:Mergus|common merganser]]
[[Category:Holarctic birds]]
[[Category:Birds described in 1758|common merganser]]
[[Category:Taxa named by Carl Linnaeus|common merganser]]
[[Category:Extant Pleistocene first appearances]]