Editing Barn swallow

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{{short description|Migratory passerine bird, and the most widespread species of swallow }}
{{Use dmy dates|date=September 2020}}
{{Featured article}}
{{Speciesbox
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=BirdLife International |date=2019 |title=''Hirundo rustica'' |volume=2019 |page=e.T22712252A137668645 |doi=10.2305/IUCN.UK.2019-3.RLTS.T22712252A137668645.en |access-date=12 November 2021}}</ref>
| image = Rauchschwalbe Hirundo rustica.jpg
| image_caption = in [[Tönning]], [[Germany]]
| image2 = Barn Swallow - Hirundo Rustica - John Heinz National Wildlife Refuge, Philadelphia, Pennsylvania, USA.webm
| image2_caption = H. rustica calling in [[Philadelphia]].
| genus = Hirundo
| species = rustica
| authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| range_map = HirundoRusticaIUCN.svg
| range_map_caption = Range of ''H. rustica'' {{leftlegend|#00FF00|Breeding|outline=gray}} {{leftlegend|#008000|Resident|outline=gray}} {{leftlegend|#00FFFF|Passage|outline=gray}} {{leftlegend|#007FFF|Non-breeding|outline=gray}}
| synonyms = * ''Hirundo erythrogaster'' {{small|(Boddaert,&nbsp;1783)}}
| subdivision_ranks = Subspecies
| subdivision = 6, see [[#Subspecies|text]]
}}

The '''barn swallow''' ('''''Hirundo rustica''''') is the most widespread species of [[swallow]] in the world, occurring on all continents, with vagrants reported even in Antarctica.<ref name=":1">{{Cite journal |last1=Scordato |first1=Elizabeth S.C. |last2=Safran |first2=Rebecca J. |date=2014 |title=Geographic variation in sexual selection and implications for speciation in the Barn Swallow |url=https://www.researchgate.net/publication/273134031 |journal=Avian Research |volume=5 |doi=10.1186/s40657-014-0008-4|doi-access=free }}</ref><ref>{{Cite web |last=Kaufman |first=Ken |date=2017 |title=The Barn Swallow Is Slowly Conquering the World |url=https://www.audubon.org/news/the-barn-swallow-slowly-conquering-world |access-date=12 March 2024 |website=Audubon}}</ref> It is a distinctive passerine bird with blue upperparts and a long, deeply forked tail. In [[English-speaking world|Anglophone]] Europe, it is just called the '''swallow'''; in northern Europe, it is the only member of family [[Hirundinidae]] called a "swallow" rather than a "[[Martin (bird)|martin]]".

There are six subspecies of barn swallow, which breed across the Northern Hemisphere.<ref name=":1" /> Two subspecies, (''H. r. savignii and H. r. transitiva'') have fairly restricted ranges in the Nile valley and eastern Mediterranean, respectively.<ref name=":1" /> The other four are more widespread, with winter ranges covering much of the Southern Hemisphere.<ref>{{Cite book |last1=del Hoyo |first1=J. |title=Handbook of the Birds of the World: Alive |last2=Elliott |first2=A. |date=2014 |publisher=Lynx Edicions |location=Spain |chapter=Barn Swallow (Hirundo rustica)}}</ref>

The barn swallow is a bird of open country that normally nests in man-made structures and consequently has spread with human expansion. It builds a cup [[bird nest|nest]] from mud pellets in barns or similar structures and feeds on insects caught in flight.<ref>{{Cite web |title=Barn Swallow {{!}} Audubon Field Guide |url=https://www.audubon.org/field-guide/bird/barn-swallow |access-date=2024-03-13 |website=www.audubon.org |language=en}}</ref> This species lives in close association with humans, and its insect-eating habits mean that it is tolerated by humans; this acceptance was reinforced in the past by superstitions regarding the bird and its nest. There are frequent cultural references to the barn swallow in literary and religious works due to both its living in close proximity to humans and its annual migration. The barn swallow is the [[list of national birds|national bird]] of [[Austria]] and [[Estonia]].

== Description ==
[[File:Barn Swallow ebird data map.png|thumb|Reported range from observations submitted to [[eBird]] shows the migration pattern of the species{{leftlegend|#0cfc0c|Year-round range|outline=gray}}{{leftlegend|#fafa11|Summer range|outline=gray}}{{leftlegend|#21fafa|Winter range|outline=gray}}|alt=See caption]]

The adult male barn swallow of the nominate subspecies ''H. r. rustica'' is {{convert|17|–|19|cm|in|frac=2|abbr=on}} long including {{convert|2|–|7|cm|in|frac=2|abbr=on}} of elongated outer tail feathers. It has a wingspan of {{convert|32|–|34.5|cm|in|frac=4|abbr=on}} and weighs {{convert|16|–|22|g|oz|frac=16|abbr=on}}. It has steel blue upperparts and a [[rufous]] forehead, chin and throat, which are separated from the off-white underparts by a broad dark blue breast band. The outer tail feathers are elongated, giving the distinctive deeply forked "swallow tail". There is a line of white spots across the outer end of the upper tail.<ref name="BWP">{{cite book|editor1-last = Snow |editor1-first = David |editor2-last = Perrins |editor2-first=Christopher M |title = The Birds of the Western Palearctic concise edition (2 volumes) |publisher = Oxford University Press |year = 1998 |location = Oxford |isbn = 978-0-19-854099-1}} p1061–1064</ref> The female is similar in appearance to the male, but the tail streamers are shorter, the blue of the upperparts and breast band is less glossy, and the underparts paler. The juvenile is browner and has a paler rufous face and whiter underparts. It also lacks the long tail streamers of the adult.<ref name="Turner">{{cite book |title=Swallows & Martins: An Identification Guide and Handbook |last=Turner |first=Angela K |author2=Rose, Chris |location=Boston |publisher=Houghton Mifflin |year=1989 |isbn=978-0-395-51174-9 |url-access=registration |url=https://archive.org/details/swallowsmartinsi00turn }} p164–169</ref>

Although both sexes sing, female song was only recently described.<ref name="Wilkins2020">{{Cite journal|last1=Wilkins|first1=Matthew R.|last2=Odom|first2=Karan J.|last3=Benedict|first3=Lauryn|last4=Safran|first4=Rebecca J.|date=October 2020|title=Analysis of female song provides insight into the evolution of sex differences in a widely studied songbird|journal=Animal Behaviour|language=en|volume=168|pages=69–82|doi=10.1016/j.anbehav.2020.07.018|s2cid=221472750|doi-access=free}}</ref> (See below for details about song.) Calls include ''witt'' or ''witt-witt'' and a loud ''splee-plink'' when excited or trying to chase intruders away from the nest.<ref name= BWP/> The [[alarm call]]s include a sharp ''siflitt'' for predators like cats and a ''flitt-flitt'' for [[bird of prey|birds of prey]] like the [[Hobby (bird)|hobby]].<ref name = "Mullarney"/> This species is fairly quiet on the wintering grounds.<ref name = "Hilty"/>

The distinctive combination of a red face and blue breast band renders the adult barn swallow easy to distinguish from the African ''Hirundo'' species and from the [[welcome swallow]] (''Hirundo neoxena'') with which its range overlaps in [[Australasia]].<ref name = "Turner"/> In Africa the short tail streamers of the juvenile barn swallow invite confusion with juvenile [[red-chested swallow]] (''Hirundo lucida''), but the latter has a narrower breast band and more white in the tail.<ref name= "Barlow"/>

== Taxonomy ==
The barn swallow was described by [[Carl Linnaeus]] in his 1758 [[10th edition of Systema Naturae|10th edition of ''Systema Naturae'']] as ''Hirundo rustica'', characterised as "''H. rectricibus, exceptis duabus intermediis, macula alba notatîs''".<ref>{{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=191 |language=la |title-link=Systema Naturae}}</ref> ''Hirundo'' is the [[Latin]] word for "swallow"; ''rusticus'' means "of the country".<ref name=name>{{cite book|author=Lewis, Charlton T |title=A Latin dictionary for schools|year=1888|publisher=Harper & Brothers|url=https://archive.org/details/latindictionaryf00lewiuoft|isbn=978-0-19-910204-4}}</ref> This species is the only one of that genus to have a range extending into the Americas, with the majority of ''Hirundo'' species being native to Africa. This genus of blue-backed swallows is sometimes called the "barn swallows".<ref name="GillAndWright">See Gill, Frank, and Wright, Minturn, ''[[Birds of the World: Recommended English Names]]'' (Princeton 2006), {{ISBN|978-0-691-12827-6}}</ref><ref name=Turner/>

The ''[[Oxford English Dictionary]]'' dates the English [[common name]] "barn swallow" to 1851,<ref name=OED>{{Cite OED |Barn }}</ref> though an earlier instance of the [[collocation]] in an English-language context is in Gilbert White's popular book ''[[The Natural History and Antiquities of Selborne|The Natural History of Selborne]]'', originally published in 1789:
<blockquote>
The swallow, though called the chimney-swallow, by no means builds altogether in chimnies {{sic}}, but often within barns and out-houses against the rafters&nbsp;... In ''Sweden'' she builds in barns, and is called ''ladusvala'', the barn-swallow.<ref name= white>{{cite book |last=White |first=Gilbert |author-link=Gilbert White|title=The Natural History and Antiquities of Selborne |year=1789 |location=London |publisher=T. Bensley |pages=[https://archive.org/details/naturalhistorya04whitgoog/page/n185 167]–68 |isbn=978-0-905418-96-4|title-link=The Natural History and Antiquities of Selborne }}</ref>
</blockquote>
{{listen
| filename = Hirundo rustica - Barn Swallow - XC83449.ogg
| title = Recording of barn swallows
| description = Song recorded at the [[Minnesota Valley National Wildlife Refuge]]
| format = [[oggg]]
| align = left
}}
This suggests that the English name may be a [[calque]] on the Swedish term.

There are few [[Taxonomy (biology)|taxonomic]] problems within the genus, but the [[red-chested swallow]]—a resident of West Africa, the [[Congo Basin]], and [[Ethiopia]]—was formerly treated as a subspecies of barn swallow. The red-chested swallow is slightly smaller than its migratory relative, has a narrower blue breast-band, and (in the adult) has shorter tail streamers. In [[bird flight|flight]], it looks paler underneath than barn swallow.<ref name= Barlow>{{cite book |title=A Field Guide to birds of The Gambia and Senegal |last=Barlow |first=Clive |author2=Wacher, Tim|author3= Disley, Tony |location=Robertsbridge |publisher=Pica Press |year=1997 |isbn=978-1-873403-32-7}} p279</ref>

=== Subspecies ===
[[File:NML-VZ T2057 Chelidon rustica transitiva.jpg|thumb|Holotype of ''Chelidon rustica'' ''transitiva'' Hartert (NML-VZ T2057) held at World Museum, National Museums Liverpool|alt=See caption]]
[[File:Barn Swallow - Hirundo rustica.ogv|thumb|A European Barn Swallow pauses to rest on a fence post beside a freshwater lake on [[Lindisfarne]].]]

Six subspecies of barn swallow are generally recognised. In eastern Asia, a number of additional or alternative forms have been proposed, including ''saturata'' by [[Robert Ridgway]] in 1883,<ref name=ssp>{{cite journal |last=Dickinson |first=Edward C. |author-link=Edward C. Dickinson |author2=Eck, Siegfried |author3=Christopher M. Milensky |year=2002 |title=Systematic notes on Asian birds. 31. Eastern races of the barn swallow ''Hirundo rustica'' Linnaeus, 1758 |journal=Zoologische Verhandelingen, Leiden |volume=340 |pages=201–203 |issn=0024-1652 |url=http://www.repository.naturalis.nl/document/46729 |access-date=24 November 2007 |archive-date=24 July 2011 |archive-url=https://web.archive.org/web/20110724012737/http://www.repository.naturalis.nl/document/46729 |url-status=live }}</ref> ''kamtschatica'' by [[Benedykt Dybowski]] in 1883,<ref name=Dickinson/> ''ambigua'' by [[Erwin Stresemann]]<ref>{{cite journal|author= Stresemann, E |year=1940| title= Welche Rasse von ''Hirundo rustica'' bretet in Sikkim? | journal= Ornithologischen Monatsbericht |volume=48|issue=3|pages=88–89|language=de}}</ref> and ''mandschurica'' by [[Wilhelm Meise]] in 1934.<ref name= ssp/> Given the uncertainties over the validity of these forms,<ref name=Dickinson>{{cite journal |last=Dickinson |first=Edward C. |author2=René Dekker |year=2001 |title=Systematic notes on Asian birds. 13. A preliminary review of the Hirundinidae |journal=[[Zoologische Verhandelingen, Leiden]] |volume=335 |pages=127–144 |issn=0024-1652 |url=http://www.repository.naturalis.nl/document/46434 |access-date=17 November 2007 |archive-date=24 July 2011 |archive-url=https://web.archive.org/web/20110724012756/http://www.repository.naturalis.nl/document/46434 |url-status=live }}</ref><ref>{{cite journal|title=Notes on some Asiatic swallows|author=Vaurie, Charles|journal=American Museum Novitates|issue=1529|year=1951|pages=1–47|hdl=2246/3915}}</ref> this article follows the treatment of Turner and Rose.<ref name=Turner/>
* ''H. r. rustica'', the nominate European subspecies, breeds in Europe and Asia, as far north as the [[Arctic Circle]], south to North Africa, the Middle East and [[Sikkim]], and east to the [[Yenisei River]]. It migrates on a broad front to winter in Africa, [[Arabia]], and the [[Indian subcontinent]].<ref name=Turner/> The barn swallows wintering in southern Africa are from across Eurasia to at least 91°E,<ref name=safring>{{cite web |title=European Swallow ''Hirundo rustica'' |work=SAFRING results |url=http://safring.adu.org.za/search_public.php?type=species&spp=493 |publisher=Avian Demography Unit, Department of Statistical Sciences, University of Cape Town |access-date=1 December 2007 |url-status=dead |archive-url=https://web.archive.org/web/20160402115400/http://safring.adu.org.za/search_public.php?type=species&spp=493 |archive-date=2 April 2016}}</ref> and have been recorded as covering up to {{convert|11660|km|mi|abbr=on}} on their annual migration.<ref name =euring2>{{cite web |title= Bird ringing across the world |work= EURING Newsletter&nbsp;— Volume 1, November 1996 |url= http://www.euring.org/about_euring/newsletter1/ringing_across_world.htm |publisher=Euring |access-date=1 December 2007 |archive-url= https://web.archive.org/web/20071203210454/http://www.euring.org/about_euring/newsletter1/ringing_across_world.htm |archive-date= 3 December 2007 |url-status= live}}</ref> The nominate European subspecies was the first to have its genome sequenced and published.<ref>{{cite journal |author=Formenti, Giulio |year=2018 |title= SMRT long reads and Direct Label and Stain optical maps allow the generation of a high-quality genome assembly for the European barn swallow (''Hirundo rustica rustica'') |journal= GigaScience |volume=8 |issue=1 |doi= 10.1093/gigascience/giy142 |pmid=30496513 |pmc=6324554 }}</ref>
* ''H. r. transitiva'' was described by [[Ernst Hartert]] in 1910. It breeds in the Middle East from southern Turkey to Israel and is partially resident, though some birds winter in East Africa. It has orange-red underparts and a broken breast band.<ref name=Turner/> The [[holotype]] of ''Chelidon rustica transitiva'' Hartert ([https://www.biodiversitylibrary.org/page/14030619 Vog. pal. Fauna, Heft 6, 1910. p. 802]), an adult female, is held in the vertebrate zoology collection of [[National Museums Liverpool]] at [[World Museum]], with accession number NML-VZ T2057.<ref>{{Cite web|title=Vertebrate Zoology|url=https://www.gbif.org/grscicoll/collection/225db9c9-16a8-47d4-a1a2-6940bb4a2da5|access-date=2021-12-01|website=www.gbif.org|language=en|archive-date=1 December 2021|archive-url=https://web.archive.org/web/20211201235036/https://www.gbif.org/grscicoll/collection/225db9c9-16a8-47d4-a1a2-6940bb4a2da5|url-status=live}}</ref> The specimen was collected in the Plains of Esdraclon, [[Palestine (region)|Palestine]] on 16 December 1863 by [[Henry Baker Tristram]]. The specimen came to the Liverpool national collection through the purchase of Canon [[Henry Baker Tristram]]'s collection by the museum in 1896.<ref name=":0">{{Cite book|last=R. Wagstaffe|url=http://archive.org/details/type-specimens-of-birds-in-the-merseyside-county-museums-wagstaffe|title=Type Specimens of Birds in the Merseyside County Museums (formerly City of Liverpool Museums)|date=1978-12-01}}</ref>
* ''H. r. savignii'', the resident [[Egypt]]ian subspecies, was described by [[James Francis Stephens|James Stephens]] in 1817 and named for French [[zoology|zoologist]] [[Marie Jules César Savigny]].<ref name= Decker>{{cite journal |last=Dekker |first=René |year=2003 |title=Type specimens of birds. Part 2. |journal=NNM Technical Bulletin |volume=6 |page=20 |url=http://www.repository.naturalis.nl/document/43413 |access-date=24 November 2007 |archive-date=1 October 2018 |archive-url=https://web.archive.org/web/20181001062912/http://www.repository.naturalis.nl/document/43413 |url-status=live }}</ref> It resembles ''transitiva'', which also has orange-red underparts, but ''savignii'' has a complete broad breast band and deeper red hue to the underparts.<ref name = Mullarney/>
* ''H. r. gutturalis'', described by [[Giovanni Antonio Scopoli]] in 1786,<ref name= ssp/> has whitish underparts and a broken breast band. The breast is chestnut and the lower underparts more pink-buff.<ref name=rasmussen>{{cite book|author=Rasmussen, Pamela C.|author-link=Rasmussen, Pamela C.|author2=John C. Anderton|author2-link=John C. Anderton|year=2005|title=Birds of South Asia: The Ripley Guide|publisher=Smithsonian Institution and Lynx Edicions|isbn=978-84-87334-67-2|title-link=Birds of South Asia: The Ripley Guide}}</ref> The populations that breed in the central and eastern Himalayas have been included in this subspecies,<ref>{{cite journal|author=Whistler, H |year=1937| title= The breeding Swallow of the Western Himalayas|journal= Ibis |volume=79|issue=2|pages=413–415|doi=10.1111/j.1474-919X.1937.tb02182.x}}</ref> although the primary breeding range is Japan and Korea. The east Asian breeders winter across tropical Asia from India and Sri Lanka<ref>{{cite journal|author= Whistler, H |year=1940| title= The Common Swallow ''Hirundo rustica rustica'' in Ceylon|journal= Ibis|volume=82| issue=3|page=539|doi=10.1111/j.1474-919X.1940.tb01671.x}}</ref> east to Indonesia and [[New Guinea]]. Increasing numbers are wintering in Australia. It hybridises with ''H. r. tytleri'' in the [[Amur River]] area. It is thought that the two eastern Asia forms were once geographically separate, but the nest sites provided by expanding human habitation allowed the ranges to overlap.<ref name=Turner/> ''H. r. gutturalis'' is a vagrant to [[Alaska]] and [[Washington (state)|Washington]],<ref name=Sibley>{{cite book |last = Sibley |first = David |title = The North American Bird Guide |year = 2000 |publisher = Pica Press |isbn= 978-1-873403-98-3}}</ref> but is easily distinguished from the North American breeding subspecies, ''H. r. erythrogaster'', by the latter's reddish underparts.<ref name=Turner/>
* ''H. r. tytleri'', first described by [[Thomas C. Jerdon|Thomas Jerdon]] in 1864, and named for British soldier, naturalist and photographer [[Robert Christopher Tytler]],<ref name=ssp/> has deep orange-red underparts and an incomplete breast band. The tail is also longer.<ref name=rasmussen/> It breeds in central [[Siberia]] south to northern Mongolia and winters from eastern [[Bengal]] east to Thailand and Malaysia.<ref name=Turner/>
* ''H. r. erythrogaster'', the North American subspecies described by [[Pieter Boddaert]] in 1783,<ref name= ssp/> differs from the European subspecies in having redder underparts and a narrower, often incomplete, blue breast band. It breeds throughout North America, from [[Alaska]] to southern Mexico, and migrates to the [[Lesser Antilles]], Costa Rica, Panama and South America to winter.<ref name=Hilty>{{cite book |last = Hilty |first = Steven L |title = Birds of Venezuela |publisher = Christopher Helm |year = 2003 |location = London |isbn = 978-0-7136-6418-8}} p691</ref> A few may winter in the southernmost parts of the breeding range. This subspecies funnels through Central America on a narrow front and is therefore abundant on passage in the lowlands of both coasts.<ref name=Stiles>{{cite book |last = Stiles |first = Gary |author2=Skutch, Alexander |title = A guide to the Birds of Costa Rica |location=Ithaca, New York |publisher = Cornell University Press |year = 2003 |isbn = 978-0-8014-2287-4}} p343</ref> Since the 1980s, small numbers of this subspecies have been found nesting in Argentina.<ref name=Torres/>[[File:BarnSwallow cajay.jpg|thumb|right|''H. r. erythrogaster'' resting on a twig in Washington State, US]]

The short wings, red belly and incomplete breast band of ''H. r. tytleri'' are also found in ''H. r. erythrogaster'', and [[DNA]] analyses show that barn swallows from North America colonised the [[Lake Baikal|Baikal]] region of Siberia, a dispersal direction opposite to that for most changes in distribution between North America and Eurasia.<ref name = zinkpavlova>{{cite journal |last1=Zink |first1=Robert M |last2= Pavlova|first2=Alexandra|last3=Rohwer |first3= Sievert|last4 =Drovetski|first4= Sergei V|year= 2006 |title=Barn swallows before barns: population histories and intercontinental colonization |journal= Proceedings of the Royal Society B: Biological Sciences|volume=273 |issue=1591 |pages=1245–1251 |doi=10.1098/rspb.2005.3414  |pmid=16720398 |pmc=1560278}}</ref>

== Behaviour ==
=== Habitat and range ===

The preferred habitat of the barn swallow is open country with low vegetation, such as pasture, meadows and farmland, preferably with nearby water. This swallow avoids heavily wooded or precipitous areas and densely built-up locations. The presence of accessible open structures such as barns, stables, or culverts to provide nesting sites, and exposed locations such as wires, roof ridges or bare branches for perching, are also important in the bird's selection of its breeding range.<ref name="BWP" />

Barn swallows are semi-colonial, settling in groups from a single pair to a few dozen pairs, particularly in larger wooden structures housing animals. The same individuals often breed at the same site year after year, although settlement choices have been experimentally shown to be predicted by nest availability rather than any characteristics of available mates.<ref>{{Cite journal|last=Safran|first=Rebecca J.|date=2007-06-13|title=Settlement patterns of female barn swallows Hirundo rustica across different group sizes: access to colorful males or favored nests?|url=http://link.springer.com/10.1007/s00265-007-0366-6|journal=Behavioral Ecology and Sociobiology|language=en|volume=61|issue=9|pages=1359–1368|doi=10.1007/s00265-007-0366-6|bibcode=2007BEcoS..61.1359S |s2cid=24784564|issn=0340-5443|access-date=10 June 2021|archive-date=14 September 2022|archive-url=https://web.archive.org/web/20220914222544/https://link.springer.com/article/10.1007/s00265-007-0366-6|url-status=live|url-access=subscription}}</ref> Because it takes around 2 weeks for a pair to build a nest from mud, hair, and other materials, old nests are highly prized.<ref>{{Cite journal|last=Safran|first=Rebecca Jo|date=November 2006|title=Nest-site selection in the barn swallow, Hirundo rustica: What predicts seasonal reproductive success?|url=http://dx.doi.org/10.1139/z06-176|journal=Canadian Journal of Zoology|volume=84|issue=11|pages=1533–1539|doi=10.1139/z06-176|bibcode=2006CaJZ...84.1533S |issn=0008-4301|url-access=subscription}}</ref>

[[File:Barn swallow (Hirundo rustica rustica) juveniles.jpg|thumb|right|''H. r. rustica'' juveniles|alt=A group of juvenile swallow resting in a tree.]]
[[File:BarnSwallowSlowMo960.ogv|thumb|The movement of two swallows in slow motion|alt=See caption]]

This species breeds across the Northern Hemisphere from sea level to {{convert|2700|m|ft|abbr=on}},<ref name=BirdLife>{{cite web |title = BirdLife International Species factsheet: ''Hirundo rustica'' |publisher = BirdLife International |access-date = 6 December 2007 |url = http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=7116&m=1 |archive-date = 15 December 2008 |archive-url = https://web.archive.org/web/20081215081352/http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=7116&m=1 |url-status = live }}</ref> but to {{convert|3000|m|ft|abbr=on}} in the [[Caucasus]]<ref name=BWP/> and North America,<ref name= umich/> and it is absent only from deserts and the cold northernmost parts of the continents. Over much of its range, it avoids towns, and in Europe is replaced in urban areas by the [[Common house martin|house martin]]. However, in [[Honshū]], Japan, the barn swallow is a more urban bird, with the [[Eastern red-rumped swallow|red-rumped swallow]] (''Cecropis daurica'') replacing it as the rural species.<ref name= Turner/>

In winter, the barn swallow is cosmopolitan in its choice of habitat, avoiding only dense forests and deserts.<ref name=SASOL>{{cite book |title=SASOL Birds of Southern Africa |last= Sinclair |first=Ian |author2= Hockey, Phil|author3= Tarboton, Warwick |location=Cape Town |publisher=Struik |year=2002 |isbn= 978-1-86872-721-6}} p294</ref> It is most common in open, low vegetation habitats, such as [[savanna]] and ranch land, and in Venezuela, South Africa and [[Trinidad and Tobago]] it is described as being particularly attracted to burnt or harvested [[sugarcane]] fields and the waste from the cane.<ref name = Hilty/><ref name = mercy/><ref name = ffrench>{{cite book |last = ffrench<!--this name should not be capitalized--> |first = Richard |title = A Guide to the Birds of Trinidad and Tobago |edition = 2nd |year = 1991 |location=Ithaca, New York |publisher = Comstock Publishing |isbn = 978-0-8014-9792-6}} p315–6</ref> In the absence of suitable roost sites, they may sometimes roost on wires where they are more exposed to predators.<ref>{{cite journal|author=George, PV|year=1965|title=Swallows ''Hirundo rustica'' Linnaeus roosting on wires|journal=Journal of the Bombay Natural History Society|volume=62|issue=1|page=160|url=https://biodiversitylibrary.org/page/47953533|access-date=23 December 2017|archive-date=26 July 2020|archive-url=https://web.archive.org/web/20200726145627/https://www.biodiversitylibrary.org/page/47953533|url-status=live}}</ref> Individual birds tend to return to the same wintering locality each year<ref name= burton/> and congregate from a large area to [[communal roosting|roost]] in reed beds.<ref name=mercy/> These roosts can be extremely large; one in Nigeria had an estimated 1.5 million birds.<ref name=Bijlsma/> These roosts are thought to be a protection from predators, and the arrival of roosting birds is synchronised in order to overwhelm predators like [[African hobby|African hobbies]]. The barn swallow has been recorded as breeding in the more temperate parts of its winter range, such as the mountains of Thailand and in central Argentina.<ref name= Turner/><ref name= Lekagul>{{cite book |last = Lekagul |first = Boonsong |author2=Round, Philip |title = A Guide to the Birds of Thailand |year = 1991 |location=Bangkok |publisher = Saha Karn Baet |isbn = 978-974-85673-6-5}} p234</ref>

Migration of barn swallows between Britain and South Africa was first established on 23 December 1912 when a bird that had been ringed by James Masefield at a nest in Staffordshire, was found in Natal.<ref name=MigrationAtlas>{{cite book |title=The Migration Atlas: Movements of the Birds of Britain and Ireland |publisher=[[T & AD Poyser]] | year=2002 |isbn= 978-0-7136-6514-7 |editor=Wernham, Chris |page = 462 }}</ref> As would be expected for a long-distance migrant, this bird has occurred as a vagrant to such distant areas as Hawaii, [[Bermuda]], Greenland, [[Tristan da Cunha]], the [[Falkland Islands]],<ref name= Turner/> and even Antarctica.<ref name="Korczak-Abshire">{{cite journal |last1=Korczak-Abshire |first1=Małgorzata |last2=Lees |first2=Alexander |last3=Jojczyk |first3=Agata |date=2001 |title=First documented record of barn swallow (''Hirundo rustica'') in the Antarctic |url=https://www.researchgate.net/publication/365362066 |journal=Polish Polar Research |volume=32 |issue=4 |pages=355–360 |doi=10.2478/v10183-011-0021-9 |doi-access=free}}</ref>

=== Feeding ===
[[File:Swallow August 2013-2.jpg|thumb|Chicks in the nest|alt=Three chicks in a nest with their beaks open.]]

The barn swallow is similar in its habits to other aerial [[insectivore]]s, including other swallow species and the unrelated [[Swift (bird)|swift]]s. It is not a particularly fast flier, with a speed estimated at {{convert|11|m/s|km/h|abbr=on}}, up to {{convert|20|m/s|km/h|abbr=on}} and a wing beat rate of approximately 5, up to 7–9 times each second.<ref name= flight>{{cite journal|last= Liechti|first= Felix|author2= Bruderer, Lukas|date= 15 August 2002|url= http://jeb.biologists.org/cgi/reprint/205/16/2461|title= Wingbeat frequency of barn swallows and house martins: a comparison between free flight and wind tunnel experiments|journal= The Journal of Experimental Biology|volume= 205|issue= 16|pages= 2461–2467|doi= 10.1242/jeb.205.16.2461|pmid= 12124369|access-date= 21 May 2009|archive-date= 15 August 2009|archive-url= https://web.archive.org/web/20090815022433/http://jeb.biologists.org/cgi/reprint/205/16/2461|url-status= live|url-access= subscription}}</ref><ref name= Park>{{cite journal |last=Park |first=Kirsty |author2=Rosén, Mikael|author3= Hedenström, Anders |year= 2001|title=Kinematics of the barn swallow (''Hirundo rustica'') over a wide range of speeds in a wind tunnel |journal=The Journal of Experimental Biology |volume=204 |issue=15 |pages=2741–2750 |doi=10.1242/jeb.204.15.2741 |url=http://jeb.biologists.org/cgi/content/full/204/15/2741|pmid=11533124 |hdl=1893/306 |issn=0022-0949| archive-url= https://web.archive.org/web/20071109084723/http://jeb.biologists.org/cgi/content/full/204/15/2741| archive-date= 9 November 2007 | url-status= live|hdl-access=free }}</ref>

The barn swallow typically feeds in open areas<ref>{{cite book|author=Angela Turner|title=The Barn Swallow|url=https://books.google.com/books?id=bpfGYOqRDW0C&pg=PA41|date=29 January 2010|publisher=Bloomsbury Publishing|isbn=978-1-4081-2821-3|page=41|access-date=14 July 2017|archive-date=26 July 2020|archive-url=https://web.archive.org/web/20200726150505/https://books.google.com/books?id=bpfGYOqRDW0C&pg=PA41|url-status=live}}</ref> {{convert|7|–|8|m|ft|abbr=on}} above shallow water or the ground often following animals, humans or farm machinery to catch disturbed insects, but it will occasionally pick prey items from the water surface, walls and plants.<ref name=BWP/> Swallows have been observed feeding on insects that fly around active [[white stork]] nests as well.<ref>{{Cite journal |last1=Tryjanowski |first1=Piotr |last2=Jankowiak |first2=Łukasz |last3=Myczko |first3=Łukasz |last4=Mikula |first4=Peter |last5=Łuczak |first5=Andrzej |date=2024-01-25 |title=White stork Ciconia ciconia nests as an attractant to birds and bats |journal=Journal of Ornithology |volume=165 |issue=2 |pages=551–555 |language=en |doi=10.1007/s10336-023-02143-y |issn=2193-7192|doi-access=free |bibcode=2024JOrni.165..551T }}</ref> In the breeding areas, large [[fly|flies]] make up around 70% of the diet, with [[aphid]]s also a significant component. However, in Europe, the barn swallow consumes fewer aphids than the [[Common house martin|house]] or [[sand martin]]s.<ref name=BWP/> On the wintering grounds, [[Hymenoptera]], especially flying [[ant]]s, are important food items.<ref name=Turner/> [[Grasshopper]]s, [[Cricket (insect)|cricket]]s, [[dragonflies]], [[beetle]]s and [[moth]]s are also preyed upon.<ref>{{cite web | url=https://animaldiversity.org/accounts/Hirundo_rustica/ | title=Hirundo rustica (Barn swallow) | website=[[Animal Diversity Web]] }}</ref> When egg-laying, barn swallows hunt in pairs, but otherwise will form often [[Group size measures|large flocks]].<ref name=Turner/>

The amount of food a clutch will get depends on the size of the clutch, with larger clutches getting more food on average. The timing of a clutch also determines the food given; later broods get food that is smaller in size compared to earlier broods. This is because larger insects are too far away from the nest to be profitable in terms of energy expenditure.<ref name="Waugh1978">{{cite thesis|type=PhD|last=Waugh|first=David R.|date=1978|title=Predation strategies in aerial feeding birds|publisher=University of Stirling}}</ref>

[[Isotope]] studies have shown that wintering populations may utilise different feeding habitats, with British breeders feeding mostly over grassland, whereas Swiss birds utilised woodland more.<ref name= Evans>{{cite journal|last= Evans|first= K. L. |author2= Wadron, S.|author3= Bradbury, R. B. |year= 2003|title= Segregation in the African wintering grounds of English and Swiss Barn Swallows ''Hirundo rustica'': a stable isotope study |journal= Bird Study|volume= 50|issue= 3|pages= 294–299|doi= 10.1080/00063650309461322 |s2cid= 82263008 |doi-access= free}}</ref> Another study showed that a single population breeding in [[Denmark]] actually wintered in two separate areas.<ref name= Mollerhobson>{{cite journal|year= 2004|title= Heterogeneity in stable isotope profiles predicts coexistence of populations of barn swallows ''Hirundo rustica'' differing in morphology and reproductive performance |journal= Proceedings of the Royal Society of London. Series B: Biological Sciences|volume= 271|issue= 1546|pages= 1355–1362 | doi = 10.1098/rspb.2003.2565|pmid= 15306333|last1= Møller|first1= AP|last2= Hobson|first2= K A|issn= 0962-8452|pmc= 1691733}}</ref>

The barn swallow drinks by skimming low over lakes or rivers and scooping up water with its open mouth.<ref name = umich/> This bird bathes in a similar fashion, dipping into the water for an instant while in flight.<ref name= burton>{{cite book |last = Burton |first = Robert |title = Bird behaviour |year = 1985 |location = London |publisher = Granada |isbn = 978-0-246-12440-1 |url-access = registration |url = https://archive.org/details/birdbehaviour0000burt }}</ref>

Swallows gather in communal roosts after breeding, sometimes thousands strong. Reed beds are regularly favoured, with the birds swirling ''en masse'' before swooping low over the reeds.<ref name= Mullarney >{{cite book |last = Mullarney |first = Killian |author2= Svensson, Lars|author3= Zetterstrom, Dan|author4= Grant, Peter |title = Collins Bird Guide |year = 1999 |location=London |publisher = HarperCollins |isbn = 978-0-00-219728-1}} p242</ref> Reed beds are an important source of food prior to and whilst on migration; although the barn swallow is a diurnal migrant that can feed on the wing whilst it travels low over ground or water, the reed beds enable fat deposits to be established or replenished.<ref name=Euring>{{cite web|last=Pilastro |first=Andrea |title=The EURING Swallow Project in Italy |url=http://www.euring.org/about_euring/newsletter2/euring_swallows_italy.htm |date=December 1998 |work=Euring Newsletter, Volume 2 |access-date=1 December 2007 |archive-url=https://web.archive.org/web/20071203210458/http://www.euring.org/about_euring/newsletter2/euring_swallows_italy.htm |archive-date=3 December 2007 |url-status=dead }}</ref>

=== Song ===
Males sing to defend small territories (when living in colonies, less so in solitary pairs) and to attract mates. Males sing throughout the breeding season, from late April into August in many parts of the range. Their song is made up of a "twitter warble," followed by a rising "P-syllable" in European ''H. r. rustica'' and the North American ''H. r. erythrogaster.''<ref name="Wilkins2018">{{Cite journal|last1=Wilkins|first1=Matthew R|last2=Scordato|first2=Elizabeth S C|last3=Semenov|first3=Georgy A|last4=Karaardiç|first4=Hakan|last5=Shizuka|first5=Daizaburo|last6=Rubtsov|first6=Alexander|last7=Pap|first7=Peter L|last8=Shen|first8=Sheng-Feng|last9=Safran|first9=Rebecca J|date=2018-03-30|title=Global song divergence in barn swallows (Hirundo rustica): exploring the roles of genetic, geographical and climatic distance in sympatry and allopatry|url=https://academic.oup.com/biolinnean/article/123/4/825/4943524|journal=Biological Journal of the Linnean Society|language=en|volume=123|issue=4|pages=825–849|doi=10.1093/biolinnean/bly012|issn=0024-4066|access-date=10 June 2021|archive-date=10 June 2021|archive-url=https://web.archive.org/web/20210610023112/https://academic.oup.com/biolinnean/article/123/4/825/4943524|url-status=live|url-access=subscription}}</ref> In all subspecies, this is followed by a short "Q-syllable" and a trilled series of pulses, termed the "rattle."<ref name="Galeotti1996">{{Cite journal|last1=GALEOTTI|first1=PAOLO|last2=SAINO|first2=NICOLA|last3=SACCHI|first3=ROBERTO|last4=MØLLER|first4=ANDERS PAPE|date=April 1997|title=Song correlates with social context, testosterone and body condition in male barn swallows|url=http://dx.doi.org/10.1006/anbe.1996.0304|journal=Animal Behaviour|volume=53|issue=4|pages=687–700|doi=10.1006/anbe.1996.0304|s2cid=54358836|issn=0003-3472|access-date=10 June 2021|archive-date=14 September 2022|archive-url=https://web.archive.org/web/20220914222545/https://www.sciencedirect.com/science/article/abs/pii/S0003347296903048?via%3Dihub|url-status=live|url-access=subscription}}</ref> The rattle is sometimes followed by a terminal "Ω-Note" in some subspecies' populations, and always at the end of ''H. r. tytleri'' song.<ref name="Wilkins2018"/>

Female songs are much shorter than male songs, and are only produced during the early part of the breeding season.<ref name="Wilkins2020"/> Females sing spontaneously, though infrequently, and will also countersing in response to each other.<ref name="Wilkins2020"/>

=== Breeding ===

[[File:Hirundo rustica MHNT.jpg |Swallow eggs, hatched|thumb|alt=See caption]]

The male barn swallow returns to the breeding grounds before the females and selects a nest site, which is then advertised to females with a circling flight and song.<ref name=BWP/> Plumage may be used to advertise: in some populations, like in the subspecies ''H. r. gutturalis'', darker ventral plumage in males is associated with higher breeding success. In other populations,<ref name="LiuScordato2018">{{cite journal|last1=Liu|first1=Yu|last2=Scordato|first2=Elizabeth S. C.|last3=Safran|first3=Rebecca|last4=Evans|first4=Matthew|s2cid=19235964|title=Ventral colour, not tail streamer length, is associated with seasonal reproductive performance in a Chinese population of barn swallows (''Hirundo rustica gutturalis'')|journal=Journal of Ornithology|volume=159|issue=3|year=2018|pages=675–685|issn=2193-7192|doi=10.1007/s10336-018-1555-y|bibcode=2018JOrni.159..675L }}</ref> the breeding success of the male is related to the length of the tail streamers, with longer streamers being more attractive to the female.<ref name=BWP/><ref name = Saino>{{cite journal |last=Saino |first=Nicola|author2=Romano, Maria|author3=Sacchi|author4=Roberto|author5=Ninni, Paola|author6=Galeotti, Paolo|author7= Møller, Anders Pape |s2cid=35334066|date=September 2003 |title=Do male barn swallows (''Hirundo rustica'') experience a trade-off between the expression of multiple sexual signals? |journal=Behavioral Ecology and Sociobiology |volume=54 |issue=5 |pages=465–471 |doi=10.1007/s00265-003-0642-z|bibcode=2003BEcoS..54..465S }}</ref> Males with longer tail feathers are generally longer-lived and more disease resistant, females thus gaining an indirect fitness benefit from this form of selection, since longer tail feathers indicate a genetically stronger individual which will produce offspring with enhanced vitality.<ref name= Moller/> Males in northern Europe have longer tails than those further south, whereas in Spain the male's tail streamers are only 5% longer than the female's; in Finland, the difference is 20%. In Denmark, the average male tail length increased by 9% between 1984 and 2004, but it is possible that climatic changes may lead in the future to shorter tails if summers become hot and dry.<ref name= BB102/>

[[File:Hirundo rustica 14105.JPG|Older chicks in nest|alt=see caption|thumb|left]]

Males with long streamers also have larger white tail spots, and since feather-eating [[chewing louse|bird lice]] prefer white feathers, large white tail spots without [[Parasitism|parasite]] damage again demonstrate breeding quality; a positive association exists between spot size and the number of offspring produced each season.<ref name= Kose>{{cite journal |last=Kose |first=Mati |author2=Mänd, Raivo|author3=Møller, Anders Pape |s2cid=24583746 |date=December 1999 |title=Sexual selection for white tail spots in the barn swallow in relation to habitat choice by feather lice |journal=Animal Behaviour |volume=58 |issue=6 |pages=1201–1205 |doi=10.1006/anbe.1999.1249 |pmid=10600140 |issn=0003-3472}}</ref>

The breeding season of the barn swallow is variable: in the southern part of the range, the breeding season usually is from February or March to early to mid September, although some late second and third broods finish in October. In the northern part of the range, it usually starts late May to early June and ends the same time as the breeding season of the southernmost birds.<ref name="Turner2010">{{cite book|author=Angela Turner|title=The Barn Swallow|url=https://books.google.com/books?id=bpfGYOqRDW0C&pg=PA113|date=29 January 2010|publisher=Bloomsbury Publishing|isbn=978-1-4081-2821-3|pages=113–114|access-date=14 July 2017|archive-date=26 July 2020|archive-url=https://web.archive.org/web/20200726150441/https://books.google.com/books?id=bpfGYOqRDW0C&pg=PA113|url-status=live}}</ref>

Both sexes defend the nest, but the male is particularly aggressive and territorial.<ref name=Turner/> Once established, pairs stay together to breed for life, but extra-pair [[Mating|copulation]] is common, making this species [[gene]]tically [[Animal sexual behaviour#Polygamy|polygamous]], despite being socially [[monogamy in animals|monogamous]].<ref>
{{cite journal |last=Møller |first=Anders Pape |author2=Tegelstrom, Håkan |s2cid=33591800 |date=November 1997 |title=Extra-pair paternity and tail ornamentation in the barn swallow |journal=Behavioral Ecology and Sociobiology |volume=41 |issue=5 |pages=353–360 |doi=10.1007/s002650050395}}</ref> Males guard females actively to avoid being [[cuckold]]ed.<ref>
{{cite journal |last=Møller |first=Anders Pape |s2cid=24056440 |date=October 1985 |title=Mixed reproductive strategy and mate guarding in a semi-colonial passerine, the swallow ''Hirundo rustica'' |journal=Behavioral Ecology and Sociobiology |volume=17 |issue=4 |pages=401–408 |doi=10.1007/BF00293220|bibcode=1985BEcoS..17..401M }}</ref> Males may use deceptive alarm calls to disrupt extrapair copulation attempts toward their mates.<ref>{{cite journal |last=Møller |first=Anders Pape |year=1990 |title=Deceptive use of alarm calls by male swallows, ''Hirundo rustica'': a new paternity guard |journal=Behavioral Ecology |volume=1 |issue=1 |pages=1–6 |doi=10.1093/beheco/1.1.1}}</ref>

As its name implies, the barn swallow typically nests inside accessible buildings such as barns and stables, or under bridges and wharves.<ref name="Duffin"/> Before man-made sites became common, it nested on cliff faces or in caves, but this is now rare.<ref name=Turner/> The neat cup-shaped nest is placed on a beam or against a suitable vertical projection. It is constructed by both sexes, although more often by the female, with mud pellets collected in their beaks and lined with grasses, feathers, algae<ref name="Duffin">{{cite journal|last=Duffin|first=K.|year=1973|title=Barn Swallows use freshwater and marine algae in nest construction|journal=Wilson Bull.|volume=85|pages=237–238}}</ref> or other soft materials.<ref name=Turner/> The nest building ability of the male is also sexually selected; females will lay more eggs and at an earlier date with males who are better at nest construction, with the opposite being true with males that are not.<ref name="SolerCuervo1998">{{cite journal|last1=Soler|first1=Juan José|last2=Cuervo|first2=José Javier|last3=Møller|first3=Anders Pape|last4=De Lope|first4=Florentino|s2cid=12957069|title=Nest building is a sexually selected behaviour in the barn swallow|journal=Animal Behaviour|volume=56|issue=6|year=1998|pages=1435–1442|issn=0003-3472|doi=10.1006/anbe.1998.0938|pmid=9933540}}</ref> After building the nest, barn swallows may nest colonially where sufficient high-quality nest sites are available, and within a colony, each pair defends a territory around the nest which, for the European subspecies, is {{convert|4|to|8|m2|sqft|sigfig=1|abbr=on}} in size. [[Group size measures|Colony size]] tends to be larger in North America.<ref name= umich/>

[[File:Hirundo rustica -West Sussex, England -chick-8.jpg|right|thumb|A juvenile swallow on a red brick in Sussex]]

In North America at least, barn swallows frequently engage in a [[Mutualism (biology)|mutualist]] relationship with [[osprey]]s. Barn swallows will build their nest below an osprey nest, receiving protection from other birds of prey that are repelled by the exclusively fish-eating ospreys. The ospreys are alerted to the presence of these predators by the alarm calls of the swallows.<ref name= umich/>

Barn swallows will normally raise two broods, with the original nest being reused for the second brood and being repaired and reused in subsequent years. The female lays two to seven, but typically four or five, reddish-spotted white eggs.<ref name=Turner/> The clutch size is influenced by latitude, with clutch sizes of northern populations being higher on average than southern populations.<ref name="Moller1984">{{cite journal|last1=Moller|first1=Anders Pape|title=Geographical trends in breeding parameters of swallows ''Hirundo rustica'' and house martins ''Delichon urbica''|journal=Ornis Scandinavica|volume=15|issue=1|year=1984|pages=43–54|issn=0030-5693|doi=10.2307/3676002|jstor=3676002}}</ref> The eggs are {{convert|20|x|14|mm|in|frac=8|abbr=on}} in size, and weigh {{convert|1.9|g|gr|abbr=off}}, of which 5% is shell. In Europe, the female does almost all the [[avian incubation|incubation]], but in North America the male may incubate up to 25% of the time. The incubation period is normally 14–19 days, with another 18–23 days before the [[altricial]] chicks fledge. The fledged young stay with, and are fed by, the parents for about a week after leaving the nest. Occasionally, first-year birds from the first brood will assist in feeding the second brood.<ref name=Turner/> Compared to those from early broods, juvenile barn swallows from late broods have been found to migrate at a younger age, fuel less efficiently during migration and have lower return rates the following year.<ref>{{cite journal |author1= Raja-aho, S. |author2= Eeva, T. | author3= Suorsa, P. |author4= Lehikoinen, E. | year=2017| title= Juvenile Barn Swallows ''Hirundo rustica'' L. from late broods start autumn migration younger, fuel less effectively and show lower return rates than juveniles from early broods | journal=Ibis| volume=159| pages=892–901| doi=10.1111/ibi.12492 | issue=4| doi-access=free }}</ref>

[[File:Barn swallow (feeding) at Tennōji Park in Osaka, June 2016.jpg|Juvenile being fed|thumb|left|alt=A swallow is feeding an insect to another swallow]]

The barn swallow will [[mobbing behavior|mob]] intruders such as cats or [[accipiter]]s that venture too close to their nest, often flying very close to the threat.<ref name = Moller>
{{cite book |last=Møller |first=Anders Pape |year=1994 |title=Sexual Selection and the Barn Swallow |location=Oxford |publisher=Oxford University Press |isbn=978-0-19-854028-1| page=245}}</ref> Adult barn swallows have few predators, but some are taken by accipiters, [[falcon]]s, and [[owl]]s. [[Brood parasite|Brood parasitism]] by [[cowbird]]s in North America or [[cuckoo]]s in Eurasia is rare.<ref name=BWP/><ref name= umich/>

Hatching success is 90% and the fledging survival rate is 70–90%. Average mortality is 70–80% in the first year and 40–70% for the adult. Although the record age is more than 11 years, most survive less than four years.<ref name=Turner/> Barn swallow nestlings have prominent red gapes, a feature shown to induce feeding by parent birds. An experiment in manipulating brood size and immune system showed the vividness of the gape was positively correlated with T-cell–mediated immunocompetence, and that larger brood size and injection with an antigen led to a less vivid gape.<ref name="Saino03">{{cite journal|author=Saino, Nicola|author2=Ambrosini, Roberto|author3=Martinelli, Roberta|author4=Ninni, Paola|author5=Møller, Anders Pape |year=2003 |title=Gape coloration reliably reflects immunocompetence of barn swallow (''Hirundo rustica'') nestlings |journal=Behavioral Ecology |volume=14 |issue=1 |pages=16–22 |url=http://www.georgealozano.com/papers/Saino2K03.pdf|doi=10.1093/beheco/14.1.16 |url-status=dead |archive-url=https://web.archive.org/web/20110711084908/http://www.georgealozano.com/papers/Saino2K03.pdf |archive-date=11 July 2011|doi-access=free }}</ref>

The barn swallow has been recorded as [[hybrid (biology)|hybridising]] with the [[American cliff swallow|cliff swallow]] (''Petrochelidon pyrrhonota'') and the [[cave swallow]] (''P. fulva'') in North America, and the [[house martin]] (''Delichon urbicum'') in Eurasia, the cross with the latter being one of the most common passerine hybrids.<ref name = Moller/>

== Parasites and predators ==
[[File:Feather hole.jpg|thumb|right|Feeding trace of ''Brueelia'' lice on a tail feather|alt=See caption]]

Barn swallows (and other small [[passerines]]) often have characteristic [[feather holes]] on their wing and tail feathers. These holes were suggested as being caused by [[Phthiraptera|avian lice]] such as ''[[Machaerilaemus malleus]]'' and ''[[Myrsidea rustica]]'', although other studies suggest that they are mainly caused by species of ''[[Brueelia]]''. Several other species of lice have been described from barn swallow hosts, including ''Brueelia domestica'' and ''Philopterus microsomaticus''.<ref>{{cite book|author=Møller, A P|year=1991 |chapter= Parasites, sexual ornaments and mate choice in the Barn Swallow ''Hirundo rustica''|title=Bird-parasite interactions: Ecology, evolution, and behaviour|editor1=Loye, J E |editor2=Zuk, M |publisher=Oxford University Press|location = Oxford| pages=328–343}}</ref><ref>{{cite journal|year=2008|url=http://www.zoologia.hu/list/Vas_et_al.pdf|title=The feather holes on the barn swallow ''Hirundo rustica'' and other small passerines are probably caused by ''Brueelia'' spp. lice|journal=Journal of Parasitology|volume=94|issue=6|pages=1438–1440|doi=10.1645/GE-1542.1|pmid=18576840|last1=Vas|first1=Z|last2=Csörgo|first2=T|last3=Møller|first3=A P|last4=Rózsa|first4=L|s2cid=6713948|issn=0022-3395|access-date=3 September 2009|archive-date=21 July 2011|archive-url=https://web.archive.org/web/20110721120159/http://www.zoologia.hu/list/Vas_et_al.pdf|url-status=live}}</ref> The avian lice prefer to feed on white tail spots, and they are generally found more numerously on short-tailed males, indicating the function of unbroken white tail spots as a measure of quality.<ref name="KoseMøller1999">{{cite journal|last1=Kose|first1=Mati|last2=Møller|first2=Anders Pape|s2cid=22196756|title=Sexual selection, feather breakage and parasites: the importance of white spots in the tail of the barn swallow (''Hirundo rustica'')|journal=Behavioral Ecology and Sociobiology|volume=45|issue=6|year=1999|pages=430–436|issn=0340-5443|doi=10.1007/s002650050581|bibcode=1999BEcoS..45..430K }}</ref> In Texas, the swallow bug (''[[Oeciacus vicarius]]''), which is common on species such as the [[cliff swallow]], is also known to infest barn swallows.<ref>{{cite journal|journal=J. Vector Ecol.|year=2007|volume=32 |issue=2|pages=280–284|title= The incidence of American swallow bugs (''Oeciacus vicarius'') in barn swallow (''Hirundo rustica'') colonies in northeast Texas |vauthors=Kopachena JG, Cochran BL, Nichols TB |doi=10.3376/1081-1710(2007)32[280:TIOASB]2.0.CO;2|pmid=18260518|s2cid=24386134 |issn=1081-1710}}</ref>

Predatory bats such as the [[greater false vampire bat]] are known to prey on barn swallows.<ref>{{cite journal|last=Sugathan|first=R|year=1988|title=Movement of the Eastern Swallow (''Hirundo rustica gutturalis'') ringed at Mootpuzha, Kerala|journal=Journal of the Bombay Natural History Society|volume=85|issue=2|pages=428–429|url=https://biodiversitylibrary.org/page/48804989|access-date=23 December 2017|archive-date=15 June 2020|archive-url=https://web.archive.org/web/20200615051910/https://www.biodiversitylibrary.org/page/48804989|url-status=live}}</ref> Swallows at their communal roosts attract predators and several falcon species make use of these opportunities. Falcon species confirmed as predators include the [[peregrine falcon]]<ref>{{cite journal|first=Yasuo |last=Ezaki|author2=Mizota, Hiromi |title=Wintering of a Peregrine Falcon on an electricity pylon and its food in a suburban area of western Japan|journal=Ornithological Science|volume=5|pages=211–216|year=2006|doi=10.2326/osj.5.211|issue=2}}</ref> and the [[African hobby]].<ref name=Bijlsma>{{cite journal|author1=Bijlsma R.G. |author2=van den Brink B. |name-list-style=amp |year=2005 |title=A Barn Swallow ''Hirundo rustica'' roost under attack: timing and risks in the presence of African Hobbies ''Falco cuvieri'' |journal=Ardea |volume=93 |issue=1 |pages=37–48 |url=http://ardeajournal.natuurinfo.nl/ardeapdf/a93-037-048.pdf |url-status=dead |archive-url=https://web.archive.org/web/20081031130906/http://ardeajournal.natuurinfo.nl/ardeapdf/a93-037-048.pdf |archive-date=31 October 2008}}</ref> In Africa, tigerfish ''[[Hydrocynus vittatus]]'' have been recorded to routinely leap out of the water to capture low-flying swallows.<ref>{{Cite journal |last1=O'Brien |first1=G. C. |last2=Jacobs |first2=F. |last3=Evans |first3=S. W. |last4=Smit |first4=N. J. |date=2014 |title=First observation of African tigerfish ''Hydrocynus vittatus'' predating on barn swallows ''Hirundo rustica'' in flight |url=https://onlinelibrary.wiley.com/doi/10.1111/jfb.12278 |journal=Journal of Fish Biology |language=en |volume=84 |issue=1 |pages=263–266 |doi=10.1111/jfb.12278|pmid=24354922 |bibcode=2014JFBio..84..263O |url-access=subscription }}</ref>

== Status ==
[[File:The barn swallow moment of truth.jpg|thumb|Barn swallow at the moment when its beak touches the water to have a drink in Bagmati River, Nepal|alt=See caption]]
[[File:A reflection flight of barn swallow.jpg|thumb|A reflection flight of barn swallow|alt=See caption]]
The barn swallow has an enormous range, with an estimated global extent of about {{convert|250000000|km2|sqmi|abbr=on}} and a population of 190 million individuals. The species is evaluated as [[least concern]] on the 2019 [[IUCN Red List]],<ref name="iucn status 12 November 2021" /> and has no special status under the Convention on International Trade in Endangered Species of Wild Fauna and Flora ([[CITES]]), which regulates international trade in specimens of wild animals and plants.<ref name= umich>{{cite web |last=Dewey |first=Tanya |author2=Roth, Chava |title=''Hirundo rustica'' |url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Hirundo_rustica.html |year=2002 |work=Animal Diversity Web |publisher=University of Michigan Museum of Zoology| archive-url= https://web.archive.org/web/20071210232505/http://animaldiversity.ummz.umich.edu/site/accounts/information/Hirundo_rustica.html| archive-date= 10 December 2007| url-status= live}}</ref>

This is a species that has greatly benefited historically from forest clearance, which has created the open habitats it prefers, and from human habitation, which have given it an abundance of safe man-made nest sites. There have been local declines due to the use of [[DDT]] in Israel in the 1950s, competition for nest sites with [[house sparrow]]s in the US in the 19th century, and an ongoing gradual decline in numbers in parts of Europe and Asia due to agricultural intensification, reducing the availability of insect food. However, there has been an increase in the population in North America during the 20th century with the greater availability of nesting sites and subsequent range expansion, including the colonisation of northern [[Alberta]].<ref name=Turner/>

A specific threat to wintering birds from the European populations is the transformation by the South African government of a light aircraft runway near [[Durban]] into [[King Shaka International Airport|an international airport]] for the [[2010 FIFA World Cup]]. The roughly {{convert|250|m|yd|abbr=on}} square Mount Moreland reed bed is a night roost for more than three million barn swallows, which represent 1% of the global population and 8% of the European breeding population. The reed bed lies on the flight path of aircraft using the proposed La Mercy airport, and there were fears that it would be cleared because the birds could threaten aircraft safety.<ref name= Guardian>{{cite news|title=World Cup airport 'threatens swallow population' |url=https://www.theguardian.com/travel/2006/nov/16/travelnews.conservationandendangeredspecies.environment |date=16 November 2006 |work=The Guardian |location=UK| archive-url= https://web.archive.org/web/20071203201940/http://www.guardian.co.uk/travel/2006/nov/16/travelnews.conservationandendangeredspecies.environment| archive-date= 3 December 2007 | url-status= live}}</ref><ref name = BirdLife2>{{cite press release | title = 'World Cup 2010' development threatens millions of roosting Barn Swallows| publisher = BirdLife International| date = 16 November 2006| url = http://www.birdlife.org/news/pr/2006/11/La_Mercy_BarnSwallows.html| access-date = 27 November 2007| archive-url= https://web.archive.org/web/20071204005003/http://www.birdlife.org/news/pr/2006/11/La_Mercy_BarnSwallows.html| archive-date= 4 December 2007| url-status= live}}</ref> However, following detailed evaluation, advanced radar technology will be installed to enable planes using the airport to be warned of bird movements and, if necessary, take appropriate measures to avoid the flocks.<ref name=mercy>{{cite news|last=Froneman |first=Albert |author2=Bortle, Jon |author3=Merritt, Ron |title=Draft swallow monitoring and bird aircraft interaction |url=http://eia.dubetradeport.co.za/Documents/Documents/2007Apr23/Draft%20Swallow%20Monitoring%20&%20Bird%20Aircraft%20Interaction%20Apr%202007.pdf |date=April 2007 |work=Environmental Impact Assessment Report |publisher=Dube TradePort Environmental Impact Assessment Information Center|archive-url=https://web.archive.org/web/20080625075752/http://eia.dubetradeport.co.za/Documents/Documents/2007Apr23/Draft%20Swallow%20Monitoring%20%26%20Bird%20Aircraft%20Interaction%20Apr%202007.pdf |archive-date=25 June 2008 |url-status=dead }}</ref>

[[Climate change]] may affect the barn swallow; drought causes weight loss and slow feather regrowth, and the expansion of the [[Sahara]] will make it a more formidable obstacle for migrating European birds. Hot dry summers will reduce the availability of insect food for chicks. Conversely, warmer springs may lengthen the breeding season and result in more chicks, and the opportunity to use nest sites outside buildings in the north of the range might also lead to more offspring.<ref name= BB102>{{cite journal| last=Turner | first=Angela |date=January 2009 | title= Climate change: a Swallow's eye view| journal= British Birds| volume=102 | issue=1 | pages= 3–16 }}</ref>

== Relationship with humans ==
[[File:Nederlandsche vogelen (KB) - Hirundo rustica (030b).jpg|thumb|In ''[[Nederlandsche Vogelen]]'' (1770)|alt=A coloured print of two swallows and a nest on a fence.]]

The barn swallow is an attractive bird that feeds on flying insects and has therefore been tolerated by humans when it shares their buildings for nesting. As one of the earlier migrants, this conspicuous species is also seen as an early sign of summer's approach.<ref name=Welldon/>

In the [[Old World]], the barn swallow appears to have used man-made structures and bridges since time immemorial. An early reference is in [[Virgil]]'s ''[[Georgics]]'' (29 BC), "''Ante garrula quam tignis nidum suspendat hirundo''" (Before the twittering swallow hangs its nest from the rafters).<ref name=Virgil>{{in lang|la}} Virgil, ''The Georgics'' [http://www.sacred-texts.com/cla/virgil/geo/geol04.htm Text Book IV line 307] {{Webarchive|url=https://web.archive.org/web/20210426223929/https://www.sacred-texts.com/cla/virgil/geo/geol04.htm |date=26 April 2021 }}. Retrieved 28 November 2007</ref>

Many cattle farmers believed that swallows spread ''[[Salmonella]]'' infections; however, a study in Sweden showed no evidence of the birds being reservoirs of the bacteria.<ref>{{cite journal|last=Haemig|first=Paul D. |author2=Hernandez J.|author3=Waldenström J.|author4=Bonnedahl J.|author5=Olsen B|journal=Vector-Borne and Zoonotic Diseases |title=Barn swallows (''Hirundo rustica'') test negative for ''Salmonella'' | year=2008 |volume=8 |issue=4 | pages=451–454| doi=10.1089/vbz.2007.0233| pmid=18266565| issn=1530-3667}}</ref>

=== In literature ===
Many literary references are based on the barn swallow's northward migration as a symbol of spring or summer. The [[proverb]] about the necessity for more than one piece of evidence goes back at least to [[Aristotle]]'s ''[[Nicomachean Ethics]]'': "For as one swallow or one day does not make a spring, so one day or a short time does not make a fortunate or happy man."<ref name=Welldon>{{cite book |translator-last=Welldon |translator-first=James Edward Cowell  |year=1987 |orig-year=1897 |title=The Nicomachean Ethics of Aristotle |chapter=Book 1, chapter 6 |publisher=Prometheus |location=Buffalo |isbn=978-0-87975-378-8}}</ref>

The barn swallow symbolises the coming of spring and thus love in the ''[[Pervigilium Veneris]]'', a late [[Latin]] poem. In his poem "[[The Waste Land]]", [[T. S. Eliot]] quoted the line ''"Quando fiam uti chelidon [ut tacere desinam]?"'' ("When will I be like the swallow, so that I can stop being silent?") This refers to the myth of [[Philomela (princess of Athens)|Philomela]] in which she turns into a [[nightingale]], and her sister [[Procne]] into a [[swallow]].<ref>{{cite book |last = Nims |first = John Frederick |author-link = John Frederick Nims |year = 1981 |title = The Harper Anthology of Poetry |publisher = Harper and Row |location = New York |isbn = 978-0-06-044846-2 |url-access = registration |url = https://archive.org/details/harperanthologyo00nims }}</ref>

=== In culture ===
{{further|Birds in culture}}

[[Gilbert White]] studied the barn swallow in detail in his pioneering work ''[[The Natural History of Selborne]]'', but even this careful observer was uncertain whether it migrated or hibernated in winter.<ref name= white /> Elsewhere, its long journeys were well observed, and a [[Sailor tattoos#Experiences and achievements|swallow tattoo]] is traditional among sailors as a symbol of a safe return; the tradition was that a mariner had a tattoo of this fellow wanderer after sailing {{convert|5000|nmi|km|abbr=off}}. A second swallow would be added after {{convert|10000|nmi|km|abbr=on}} at sea.<ref name =mmbc>{{cite web |title=Hardtack and marlinspikes&nbsp;– life and work aboard ship |work=Sailors' tattoos post-visit activity, teachers' handout |url=http://mmbc.bc.ca/downloads/educational_materials/Tatoos/tattoo%20activity%20text.pdf |publisher=Maritime Museum of British Columbia |access-date=2007-12-01 |archive-date=16 February 2008 |archive-url=https://web.archive.org/web/20080216073643/http://mmbc.bc.ca/downloads/educational_materials/Tatoos/tattoo%20activity%20text.pdf |url-status=live }}</ref>

In the past, the tolerance for this beneficial [[insectivore]] was reinforced by superstitions regarding damage to the barn swallow's nest. Such an act might lead to cows giving bloody milk, or no milk at all, or to hens ceasing to lay.<ref name="Cocker">{{cite book |last=Cocker |first=Mark |author2=Mabey, Richard |title=Birds Britannica |year=2005 |location=London |publisher=Chatto & Windus |isbn=978-0-7011-6907-7}}</ref> This may be a factor in the longevity of swallows' nests. Survival, with suitable annual refurbishment, for 10–15 years is regular, and one nest was reported to have been occupied for 48 years.<ref name="Cocker" />

It is depicted as the ''martlet'', ''merlette'' or ''merlot'' in [[heraldry]], where it represents younger sons who have no lands. It is also represented as lacking feet as this was a common belief at the time.<ref name = "Cooper92">{{cite book |last=Cooper |first=JC |title=Symbolic and Mythological Animals |pages=218–19 |year=1992 |publisher=Aquarian Press |location=London |isbn=978-1-85538-118-6}}</ref> As a result of a campaign by [[ornithology|ornithologists]], the barn swallow has been the national bird of Estonia since 23 June 1960, and is also the national bird of Austria.<ref name="Estonia">{{cite web |title=The State&nbsp;— Structure and Symbols |work=Estonia |url=http://www.estonia.gov.uk/estonia/state |publisher=Estonian Embassy in London |access-date=27 November 2007 |archive-url=https://web.archive.org/web/20071115000710/http://www.estonia.gov.uk/estonia/state |archive-date=15 November 2007 |url-status=dead}}</ref><ref name = Estonia2>{{cite web |title=National symbols of Estonia |url=http://www.einst.ee/publications/symbols/ |publisher=The Estonia Institute |access-date=27 November 2007| archive-url= https://web.archive.org/web/20071109221700/http://www.einst.ee/publications/symbols/| archive-date= 9 November 2007 | url-status= live}}</ref>

== See also ==
{{portal|Birds}}
* [[Bird migration#Swallow migration versus hibernation|Swallow migration versus hibernation]]
{{clear}}

== References ==
{{Reflist|30em |refs =
<ref name=Torres>{{cite journal |first1=Cristian |last1=Torres |first2=Pablo |last2=Brandolin |name-list-style=amp |title=Datos sobre la biologia reproductiva de la Golondrina Tijerita ''Hirundo rustica'' y registros novedosos de nidificatión en la provincia de San Luis y suroeste de Córdoba, Argentina |language=es |journal=Cotinga |date=June 2020 |volume=42 |pages=61–65 |url=https://www.neotropicalbirdclub.org/cotinga/C42/Articles/Cotinga42-15Torres.pdf |access-date=28 December 2020 |archive-date=23 June 2022 |archive-url=https://web.archive.org/web/20220623175425/https://www.neotropicalbirdclub.org/cotinga/C42/Articles/Cotinga42-15Torres.pdf |url-status=live }}</ref>
}}

== Further reading ==
* {{cite journal | last1 = Smiddy | first1 = P | year = 2010 | title = Post-fledging roosting at the nest in juvenile barn swallows (''Hirundo rustica'') | journal = Ir. Nat. J. | volume = 31 | pages = 44–46}}

== External links ==
{{Commons category|Hirundo rustica|Barn swallow}}
{{Wikispecies|Hirundo rustica}}
* {{BirdLife|22712252|Hirundo rustica}}
* [http://www.freesound.org/samplesViewSingle.php?id=74868 Audio recording of swallows] High quality audio recording of a group of swallows
* {{InternetBirdCollection|barn-swallow-hirundo-rustica|Barn swallow}}
* European Swallow (barn swallow) - [http://sabap2.adu.org.za/docs/sabap1/518.pdf Species text in The Atlas of Southern African Birds].
* [https://web.archive.org/web/20161210113000/http://www.mbr-pwrc.usgs.gov/id/framlst/i6130id.html Barn swallow - ''Hirundo rustica''] - USGS Patuxent Bird Identification InfoCenter
* [http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Barn_Swallow.html Barn Swallow Species Account] – Cornell Lab of Ornithology
* [http://www.birdlife.org/datazone/species/BirdsInEuropeII/BiE2004Sp7116.pdf BirdLife species' status map for Europe (pdf)].
* [https://web.archive.org/web/20141202065129/http://aulaenred.ibercaja.es/wp-content/uploads/307_BarnSwallowHrustica.pdf Ageing and sexing (PDF; 2.3 MB) by Javier Blasco-Zumeta & Gerd-Michael Heinze]
* [http://www.ornithos.de/Ornithos/Feather_Collection/Hirundo_rustica/Hirundo_rustica.htm Feathers of barn swallow (''Hirundo rustica'')] {{Webarchive|url=https://web.archive.org/web/20150924061846/http://www.ornithos.de/Ornithos/Feather_Collection/Hirundo_rustica/Hirundo_rustica.htm |date=24 September 2015 }}
* {{VIREO|Barn+Swallow|Barn swallow}}
* {{inaturalist taxon|11901}}

{{Hirundinidae}}
{{Birds in culture}}
{{Taxonbar |from=Q25429}}
{{Authority control}}

[[Category:Hirundo|barn swallow]]
[[Category:Swallows|barn swallow]]
[[Category:Holarctic birds]]
[[Category:National symbols of Austria]]
[[Category:National symbols of Estonia]]
[[Category:Birds described in 1758|barn swallow]]
[[Category:Birds of the Dominican Republic]]
[[Category:Taxa named by Carl Linnaeus|barn swallow]]
[[Category:Articles containing video clips]]
[[Category:Cosmopolitan birds]]