Editing Common tern (section)

{{Short description|Migratory seabird in the family Laridae with circumpolar distribution}}
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{{EngvarB|date=July 2022}}
{{Use dmy dates|date=July 2022}}

{{Speciesbox
| status            = LC
| status_system     = IUCN3.1
| status_ref        = <ref name="iucn status 12 November 2021">{{cite iucn|author=BirdLife International|date=2019|title=''Sterna hirundo''|volume=2019|page=e.T22694623A155537726|doi=10.2305/IUCN.UK.2019-3.RLTS.T22694623A155537726.en|access-date=12 November 2021}}</ref>
| image             = 2014-05-18 Sterna hirundo, Killingworth Lake, Northumberland 02.jpg
| image2            = Sterna-hirundo-002.ogg
| genus             = Sterna
| species           = hirundo
| authority         = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| range_map         = SternaHirundoIUCNver2018 2.png
| range_map_alt     = Map showing the breeding range of ''Sterna hirundo'' (most of temperate Northern Hemisphere), and wintering areas (coasts in tropics and Southern Hemisphere).
| range_map_caption = {{leftlegend|#00FF00|Breeding|outline=gray}} {{leftlegend|#008000|Resident|outline=gray}} {{leftlegend|#007FFF|Non-breeding|outline=gray}} {{leftlegend|#00FFFF|Passage|outline=gray}} {{leftlegend|#FF00FF|Vagrant (seasonality uncertain)|outline=blue}}
| synonyms          = *''Sterna fluviatilis'' {{small|(Naumann, 1839)}}
}}

[[File:Common-tern,web.jpg|thumbnail|Twisted head]]

The '''common tern'''<ref name = gill>{{cite web| editor = Gill, F| editor2 = Donsker D| title= IOC World Bird Names (v 2.11)|url=http://www.worldbirdnames.org/n-shorebirds.html | publisher= International Ornithologists' Union| access-date = 15 May 2014 | archive-url = https://web.archive.org/web/20131205171302/http://www.worldbirdnames.org/n-shorebirds.html | archive-date=5 December 2013}}</ref> ('''''Sterna hirundo''''') is a [[seabird]] in the family [[Laridae]]. This bird has a [[circumpolar distribution]], its four [[subspecies]] breeding in [[Temperateness|temperate]] and [[subarctic]] regions of Europe, Asia and North America. It is strongly [[bird migration|migratory]], wintering in coastal [[Tropics|tropical]] and [[Subtropics|subtropical]] regions. Breeding adults have light grey upperparts, white to very light grey underparts, a black cap, orange-red legs, and a narrow pointed bill. Depending on the subspecies, the bill may be mostly red with a black tip or all black. There are several similar species, including the partly [[Sympatry|sympatric]] [[Arctic tern]], which can be separated on [[plumage]] details, leg and bill colour, or [[Bird vocalization|vocalisation]]s.

Breeding in a wider range of habitats than any of its relatives, the common tern nests on any flat, poorly vegetated surface close to water, including beaches and islands, and it readily adapts to artificial substrates such as floating rafts. The nest may be a bare [[Bird nest#Scrape|scrape]] in sand or gravel, but it is often lined or edged with whatever debris is available. Up to three eggs may be laid, their dull colours and blotchy patterns providing [[camouflage]] on the open beach. [[Egg incubation#Avian incubation|Incubation]] is by both sexes, and the eggs hatch in around 21–22 days, longer if the colony is disturbed by predators. The downy chicks [[fledge]] in 22–28 days. Like most terns, this species feeds by plunge-diving for fish, either in the sea or in freshwater, but [[Mollusca|mollusc]]s, [[crustacean]]s and other [[invertebrate]] prey may form a significant part of the diet in some areas.

Eggs and young are vulnerable to predation by mammals such as [[rat]]s and [[American mink]], and large birds including [[gull]]s, [[owl]]s and [[heron]]s. Common terns may be infected by [[lice]], [[parasitic worm]]s, and [[mite]]s, although [[Haematozoa|blood parasites]] appear to be rare. Its large population and huge breeding range mean that this species is classed as being of [[least concern]], although numbers in North America have declined sharply in recent decades. Despite international legislation protecting the common tern, in some areas, populations are threatened by [[habitat loss]], pollution, or the disturbance of [[Bird colony|breeding colonies]].