Editing Common tern (section)

==Taxonomy==
[[Tern|Terns]] are small to medium-sized seabirds closely related to the [[gull]]s, [[Skimmer (bird)|skimmer]]s and [[skua]]s. They are gull-like in appearance, but typically have a lighter build, long pointed wings (which give them a fast, buoyant flight), a deeply forked tail, slender legs,<ref name = BWP764/> and webbed feet.<ref name= wassink>Wassink & Ort (1995) p. 78.</ref> Most species are grey above and white below, and have a black cap which is reduced or flecked with white in the non-breeding season.<ref name = BWP764>Snow & Perrin (1998) p. 764.</ref>

The common tern's closest relatives appear to be the [[Antarctic tern]],<ref name= nisbet/> followed by the [[Eurasia]]n Arctic and [[roseate tern]]s. [[Gene]]tic evidence suggests that the common tern may have diverged from an ancestral stock earlier than its relatives.<ref name=bridge>{{cite journal|last=Bridge |first=Eli S |author2=Jones, Andrew W |author3=Baker, Allan J |year=2005 |title=A phylogenetic framework for the terns (Sternini) inferred from mtDNA sequences: implications for taxonomy and plumage evolution |journal=Molecular Phylogenetics and Evolution |volume=35 |pages=459–469 |url=http://scholar.library.csi.cuny.edu/~fburbrink/Courses/Vertebrate%20systematics%20seminar/Bridge%20et%20al%202005%20.pdf |doi=10.1016/j.ympev.2004.12.010 |pmid=15804415 |issue=2 |bibcode=2005MolPE..35..459B |archive-url=https://web.archive.org/web/20110419093510/http://scholar.library.csi.cuny.edu/~fburbrink/Courses/Vertebrate%20systematics%20seminar/Bridge%20et%20al%202005%20.pdf |archive-date=19 April 2011}}</ref> No [[fossil]]s are known from North America, and those claimed in Europe are of uncertain age and species.<ref name= nisbet/>

The common tern was first described by [[Carl Linnaeus]] in his landmark 1758 [[10th edition of Systema Naturae|10th edition of ''Systema Naturae'']] under its current scientific name, ''Sterna hirundo''.<ref name = Linnaeus>{{cite book | last=Linnaeus | first=Carolus |author-link=Carl Linnaeus | title=Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. | publisher=Holmiae. (Laurentii Salvii)| year=1758| page= [https://www.biodiversitylibrary.org/item/10277#page/155/mode/1up 137]|language=la}}</ref> "Stearn" was used in [[Old English]], and a similar word was used by the [[Frisians]] for the birds.<ref name=OED>{{OED|Sterna}} Library subscription required.</ref> "Stearn" appears in the poem ''[[The Seafarer (poem)|The Seafarer]]'', written around 1000 A.D.<ref name=OED/> Linnaeus adopted this word for the genus name ''Sterna''. The Latin for [[swallow]] is ''hirundo,'' and refers here to the tern's superficial likeness to that unrelated bird, which has a similar light build and long forked tail.<ref name = hume12>Hume (1993) pp. 12–13.</ref> This resemblance also leads to the informal name "sea swallow",<ref name = rspb>{{cite web |title=Common tern |work=Birdguide |url=http://www.birdlife.org/datazone/speciesfactsheet.php?id=3270 |publisher=[[Royal Society for the Protection of Birds]] (RSPB) |access-date=25 January 2012 |archive-date=15 October 2016 |archive-url=https://web.archive.org/web/20161015233814/http://www.birdlife.org/datazone/speciesfactsheet.php?id=3270 |url-status=live }}</ref> recorded from at least the seventeenth century.<ref name= hume12/> The [[Scots language|Scots]] names ''picktarnie'',<ref>[http://www.dsl.ac.uk/getent4.php?query=pictarnie&sset=1&fset=20&printset=20&searchtype=full&dregion=form&dtext=all SND: Pictarnie] {{webarchive |url=https://web.archive.org/web/20130530115330/http://www.dsl.ac.uk/getent4.php?query=pictarnie&sset=1&fset=20&printset=20&searchtype=full&dregion=form&dtext=all |date=30 May 2013}}</ref> ''tarrock''<ref>[http://www.dsl.ac.uk/getent4.php?query=tarrock&sset=1&fset=20&printset=20&searchtype=full&dregion=form&dtext=all SND: tarrock] {{webarchive |url=https://web.archive.org/web/20130530115326/http://www.dsl.ac.uk/getent4.php?query=tarrock&sset=1&fset=20&printset=20&searchtype=full&dregion=form&dtext=all |date=30 May 2013}}</ref> and their many variants are also believed to be [[Onomatopoeia|onomatopoeic]], derived from the distinctive call.<ref name = hume12/> Because of the difficulty in distinguishing the two species, all the informal common names are shared with the [[Arctic tern]].<ref name=cocker>Cocker & Mabey (2005) pp. 246–247.</ref> There was some uncertainty whether ''Sterna hirundo'' should apply to the common tern or the arctic tern as the species are very similar and both occur in Sweden. In 1913, the Swedish zoologist [[Einar Lönnberg]] concluded that the [[Binomial nomenclature|binomial name]] ''Sterna hirundo'' applied to the common tern.<ref>{{cite journal | last=Lönnberg | first=Einar | author-link=Einar Lönnberg | date=1913 | title=On ''Sterna hirundo'' Linn. and on the name of the Common Tern | journal=Ibis | volume=1 | issue=2 | pages=301–303 | doi=10.1111/j.1474-919X.1913.tb06553.x | url=https://www.biodiversitylibrary.org/page/26514527 | access-date=16 August 2021 | archive-date=16 August 2021 | archive-url=https://web.archive.org/web/20210816133723/https://www.biodiversitylibrary.org/page/26514527 | url-status=live }}</ref>

Four subspecies of the common tern are generally recognized, although ''S.{{nbs}}h.{{nbs}}minussensis'' is sometimes considered an [[Intergradation|intergrade]] between ''S.{{nbs}}h.{{nbs}}hirundo'' and ''S.{{nbs}}h.{{nbs}}longipennis''.<ref name = hume88>Hume (1993) pp. 88–89.</ref><ref>{{cite web |title=''Sterna hirundo'' Linnaeus (1758) |url=https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=176888 |publisher=Integrated Taxonomic Information System (ITIS) |access-date=23 January 2012 |archive-date=18 October 2011 |archive-url=https://web.archive.org/web/20111018173444/http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=176888 |url-status=live }}</ref>

{| class="wikitable plainrowheaders"
|-
!scope="col" width=15% | Subspecies
!scope="col" width=15% | Image
!scope="col" width=20% | Breeding range
!scope="col" width=50% | Distinctive features
|-
!scope="row"| ''S. h. hirundo'' <br />Linnaeus, 1758
| [[File:2014-05-18 Sterna hirundo, Killingworth Lake, Northumberland 04.jpg|180px]]<br>Northumberland, UK
| Europe, North Africa, Asia east to western [[Siberia]] and [[Kazakhstan]], and North America.<ref name =olsen>Olsen & Larsson (1995) pp. 77–89.</ref>
| Differences between the North American and Eurasian populations are minimal. North American birds have a slightly shorter wing length on average, and the extent of the black tip on the upper mandible tends to be less than in birds from Scandinavia and further east in Eurasia. The proportion of black on the bill is at its minimum in the west of Europe, so British breeders are very similar to North American birds in this respect.<ref name =olsen/>
|-
!scope="row"| ''S. h. tibetana'' <br />[[Howard Saunders|Saunders]], 1876
| [[File:Common Tern, Kathmandu Valley, Nepal 1.jpg|180px]]<br>Kathmandu Valley, Nepal
| [[Himalayas]] to southern Mongolia and China.<ref name =olsen/>
| Like the nominate subspecies, but with a shorter bill and a broader black tip.<ref name=olsen/>
|-
!scope="row"| ''S. h. minussensis'' <br />[[Petr Petrovich Sushkin|Sushkin]], 1925
| [[File:Sterna hirundo, Ob River, Novosibirsk, Russia 1.jpg|180px]]<br>Novosibirsk, Russia
| [[Lake Baikal]] east to [[Outer Mongolia|northern Mongolia]] and southern [[Tibet]].<ref name= brazil/>
| Paler upper body and wings than ''S. h. longipennis'', black-tipped crimson bill.<ref name= brazil>Brazil (2008) p. 220.</ref>
|-
!scope="row"| ''S. h. longipennis''<br /> [[Alexander von Nordmann|Nordmann]], 1835
| [[File:Sterna hirundo longipennis, Tangshan, Hebei, China 01.jpg|180px]]<br>Hebei, China
| Central Siberia to China, also [[Alaska]].<ref name =olsen/>
| Darker grey than the nominate subspecies, with shorter black bill, darker red-brown legs, and longer wings.<ref name=olsen/>
|-
|}