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{{Short description|Family of seabirds (Fregatidae)}}
{{About|the type of bird|other uses|Frigate Bird (disambiguation){{!}}Frigate Bird}}
{{Featured article}}
{{Automatic taxobox
| name = Frigatebird
| fossil_range = [[Early Eocene]] to present {{fossilrange|50|present}}
| image = Male Frigate bird.jpg
| image_caption = Male [[magnificent frigatebird]]<br />(''Fregata magnificens'')<br />displaying gular pouch, [[Galápagos Islands]].
| parent_authority = [[Côme-Damien Degland|Degland]] & [[Zéphirin Gerbe|Gerbe]], 1867
| taxon = Fregata
| authority = [[Bernard Germain de Lacépède|Lacépède]], 1799
| type_species = ''Pelecanus aquilus'' ([[Ascension frigatebird]])
| type_species_authority = [[Linnaeus]], 1758
| subdivision_ranks = Species
| subdivision = * ''[[Fregata magnificens]]'' – Magnificent frigatebird
* ''[[Fregata aquila]]'' – Ascension frigatebird
* ''[[Fregata andrewsi]]'' – Christmas frigatebird
* ''[[Fregata minor]]'' – Great frigatebird
* ''[[Fregata ariel]]'' – Lesser frigatebird
| range_map = Fregata distribution.png
| range_map_caption = Range map
}}

'''Frigatebirds''' are a [[Family (biology)|family]] of [[seabird]]s called '''Fregatidae''' which are found across all [[tropical]] and subtropical oceans. The five extant species are classified in a single genus, '''''Fregata'''''. All have predominantly black plumage, long, deeply forked tails and long hooked bills. Females have white underbellies and males have a distinctive red [[gular pouch]] which they inflate during the breeding season to attract females. Their wings are long and pointed and can span up to {{convert|2.3|m|ft}}, the largest wing area to body mass ratio of any bird.

Able to soar for weeks on wind currents, frigatebirds spend most of the day in flight hunting for food, and roost on trees or cliffs at night. Their main prey are fish and [[squid]], caught when chased to the water surface by large predators such as [[tuna]]. Frigatebirds are referred to as [[Kleptoparasitism|kleptoparasites]] as they occasionally rob other seabirds for food, and are known to snatch seabird chicks from the nest. Seasonally monogamous, frigatebirds nest [[Bird colony|colonially]]. A rough nest is constructed in low trees or on the ground on remote islands. A single egg is laid each breeding season. The duration of parental care is among the longest of any bird species; frigatebirds are able to breed only every other year.

The Fregatidae are a [[sister group]] to [[Suloidea]] which consists of [[cormorant]]s, [[darter]]s, [[gannet]]s, and [[Booby|boobies]]. Three of the five extant species of frigatebirds are widespread (the [[Magnificent frigatebird|magnificent]], [[Great frigatebird|great]] and [[lesser frigatebird]]s), while two are endangered (the [[Christmas Island frigatebird|Christmas Island]] and [[Ascension Island frigatebird]]s) and restrict their breeding habitat to one small island each. The oldest fossils date to the early [[Eocene]], around 50 million years ago. Classified in the genus ''[[Limnofregata]]'', the three species had shorter, less-hooked bills and longer legs, and lived in a freshwater environment.

==Taxonomy==

===Etymology===
The term ''Frigate Bird'' itself was used in 1738 by the English naturalist and illustrator [[Eleazar Albin]] in his ''A Natural History of the Birds''. The book included an illustration of the male bird showing the red [[gular pouch]].<ref>{{cite book | last=Albin | first=Eleazar | author-link=Eleazar Albin | year=1738 | title=A Natural History of the Birds | volume= 3 | page=75 and plate 80 on previous page | url=http://gdz.sub.uni-goettingen.de/dms/load/img/?PPN=PPN469884460&DMDID=DMDLOG_0162&LOGID=LOG_0162&PHYSID=PHYS_0170 | place=London | publisher=Printed for the author and sold by William Innys }}</ref> Like the genus name, the English term is derived from the French mariners' name for the bird ''la frégate''—a [[frigate]] or fast warship.<ref>{{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, United Kingdom | isbn = 978-1-4081-2501-4 | page=[https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling/page/n164 164]}}</ref> The etymology was mentioned by French naturalist [[Jean-Baptiste Du Tertre]] when describing the bird in 1667.<ref name=tertre>{{cite book | last=du Tertre | first=du Jean-Baptiste | author-link=Jean-Baptiste Du Tertre | year=1667 | title=Histoire générale des Antilles habitées par les François | volume=2 | publisher=Thomas Joly | place=Paris | language=fr | page=269, Plate p. 246 | url=http://gallica.bnf.fr/ark:/12148/bpt6k114021k/f297.image }}</ref>{{efn|Du Tertre wrote: "Loyseau que les habitans des Indes appellent ''Fregate'' (à cause de la vistesse de son vol) n'a pas le corp plus gros qu'une poule&nbsp;..." ("The bird that the inhabitants of the Indies call "frigate" (because of the speed of its flight) has a body no larger than a chicken's.")<ref name=tertre/>}}
Alternative names and spellings include "frigate bird", "frigate-bird", "frigate", "frigate-petrel".<ref name="SOED">{{cite book|title = Shorter Oxford English Dictionary|date =2007|location = Oxford, UK|isbn = 978-0-19-920687-2|publisher = Oxford University Press}}</ref>

[[Christopher Columbus]] encountered frigatebirds when passing the [[Cape Verde Islands]] on his first voyage across the Atlantic in 1492. In his journal entry for 29 September he used the word ''rabiforçado'', modern Spanish ''rabihorcado'' or forktail.<ref>{{cite journal | last=Hartog | first=J.C. den | year=1993 | title=An early note on the occurrence of the Magnificent Frigate Bird, ''Fregata magnificens'' Mathews, 1914, in the Cape Verde Islands: Columbus as an ornithologist | journal=Zoologische Mededelingen | volume=67 | pages=361–64 | url=http://www.repository.naturalis.nl/document/149308 }}</ref><ref name=dunn>{{ cite book | last1=Dunn | first1=Oliver | last2=Kelley | first2=James E. Jr | year=1989 | title=The Diario of Christopher Columbus's First Voyage to America, 1492–1493| publisher=University of Oklahoma Press | place=Norman, Oklahoma | isbn=0-8061-2384-2 | page=[https://archive.org/details/diarioofchristop00colu/page/45 45] | url=https://archive.org/details/diarioofchristop00colu | url-access=registration }}</ref>{{efn|Columbus's journal survives in a version recorded by Bartholomé de las Casas in the 1530s. In English the entry reads: "They saw a bird that is called a frigatebird, which makes the boobies throw up what they eat in order to eat it herself, and she does not sustain herself on anything else. It is a seabird, but does not alight on the sea nor depart from land 20 leagues. There are many of these on the islands of Cape Verde."<ref name=dunn/>}} In the Caribbean frigatebirds were called Man-of-War birds by English mariners. This name was used by the English explorer [[William Dampier]] in his book ''An Account of a New Voyage Around the World'' published in 1697:<ref name=dampier>{{cite book | last=Dampier | first=James | author-link=William Dampier | year=1699 | orig-date=1697 | title=An Account of a New Voyage Around the World | publisher=James Knapton | place=London, United Kingdom | page=[https://archive.org/details/anewvoyageround01knapgoog/page/n77 49] | url=https://archive.org/details/anewvoyageround01knapgoog }}</ref>
<blockquote>The Man-of-War (as it is called by the English) is about the bigness of a Kite, and in shape like it, but black; and the neck is red. It lives on Fish yet never lights on the water, but soars aloft like a Kite, and when it sees its prey, it flys down head foremost to the Waters edge, very swiftly takes its prey out of the Sea with his Bill, and immediately mounts again as swiftly; never touching the Water with his Bill. His Wings are very long; his feet are like other Land-fowl, and he builds on Trees, where he finds any; but where they are wanting on the ground.<ref name=dampier/></blockquote>

===Classification===
Frigatebirds were grouped with [[cormorant]]s, and [[Sulidae|sulids]] ([[gannet]]s and [[booby|boobies]]) as well as pelicans in the [[genus]] ''Pelecanus'' by [[Carl Linnaeus|Linnaeus]] in 1758 in the [[10th edition of Systema Naturae|tenth edition]] of his ''[[Systema Naturae]]''. He described the distinguishing characteristics as a straight bill hooked at the tip, linear nostrils, a bare face, and fully webbed feet.<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 |location=Holmiae|publisher=Laurentii Salvii| year=1758| volume=1 | language = la |quote = Rostrum edentulum, rectum: apice adunco, unguiculato. Nares lineares. Facies nuda. Pedes digitís omnibus palmatis. |pages=132–34|url=https://www.biodiversitylibrary.org/page/727037}}</ref> The genus ''Fregata'' was introduced by French naturalist [[Bernard Germain de Lacépède]] in 1799.<ref>{{ cite book | last=Lacépède | first=Bernard Germain de | author-link=Bernard Germain de Lacépède | year=1799 | title=Discours d'ouverture et de clôture du cours d'histoire naturelle | chapter=Tableau des sous-classes, divisions, sous-division, ordres et genres des oiseux | language=fr | publisher=Plassan | place=Paris | page=15 | chapter-url=https://books.google.com/books?id=6uhAAAAAcAAJ&pg=PA89 }} Page numbering starts at one for each of the three sections.</ref> The [[type species]] was designated as the Ascension frigatebird by French zoologist [[François Marie Daudin]] in 1802.<ref>{{ cite book | last1=Lacépède  | first1=Bernard Germain de | author1-link=Bernard Germain de Lacépède | last2=Daudin | first2=François Marie | author2-link=François Marie Daudin | chapter=Tableau des sous-classes, divisions, sous-divisions, ordres et genres des oiseaux, par le Cen Lacépède; avec l'indication de toutes les espèces décrites par Buffon, et leur distribution dans chacun des genres, par F. M. Daudin | date=1799 | language=French | editor-last=Buffon | editor-first=Georges-Louis Leclerc de | editor-link=Georges-Louis Leclerc, Comte de Buffon | title=Histoire Naturelle par Buffon Dédiée au citoyen Lacépède, membre de l'Institut National | volume=14: Quadrupedes | location=Paris | publisher=P. Didot l'ainé et Firmin Didot | pages=197–346 [317] | url=https://www.biodiversitylibrary.org/page/42033567 }} Although the date of 1799 is printed on the title page, this volume was not published until 1802. For a discussion of the date see: {{ cite journal | last=Richmond | first=Charles W. | author-link=Charles Wallace Richmond | date=1899 | title=On the date of Lacépède's 'Tableaux' | journal=Auk | volume=16 | issue=4 | pages=325–329 | doi=10.2307/4069359 | jstor=4069359 | url=https://www.biodiversitylibrary.org/page/15935570 }}</ref><ref>{{ cite book | editor1-last=Mayr | editor1-first=Ernst | editor1-link=Ernst Mayr | editor2-last=Cottrell | editor2-first=G. William | year=1979 | title=Check-List of Birds of the World | volume=1 | edition=2nd | publisher=Museum of Comparative Zoology | location=Cambridge, Massachusetts | page=159 | url=https://www.biodiversitylibrary.org/page/16108799 }}</ref> [[Louis Pierre Vieillot]] described the genus name ''Tachypetes'' in 1816 for the [[great frigatebird]]. The genus name ''Atagen'' had been coined by German naturalist [[Paul Möhring]] in 1752, though this has no validity as it predates the official beginning of [[Linnaean taxonomy]].<ref name="AFD2">{{cite web|url=http://www.environment.gov.au/topics/science-and-research/abrs/databases-and-online-resources/taxa/FREGATIDAE|archive-url=https://web.archive.org/web/20141207221612/http://www.environment.gov.au/topics/science-and-research/abrs/databases-and-online-resources/taxa/FREGATIDAE|archive-date=2014-12-07 |title=Family Fregatidae Degland & Gerbe, 1867 |last=Australian Biological Resources Study|date=26 August 2014 |work=Australian Faunal Directory|publisher=Department of the Environment, Water, Heritage and the Arts, Australian Government|access-date=30 November 2014|location=Canberra, Australian Capital Territory}}</ref>

In 1874, English zoologist [[Alfred Henry Garrod]] published a study where he had examined various groups of birds and recorded which muscles of a selected group of five{{efn|1=ambiens, fermorocaudal, accessory femorocaudal, semitendinosus, and accessory tendinosus<ref name="garrod 1874"/>}}  they possessed or lacked. Noting that the muscle patterns were different among the steganopodes (classical [[Pelecaniformes]]), he resolved that there were divergent lineages in the group that should be in separate [[Family (biology)|families]], including frigatebirds in their own family Fregatidae.<ref name="garrod 1874">{{cite journal|last=Garrod|first=Alfred Henry|date=1874|title=On certain muscles of birds and their value in classification|journal=Proceedings of the Zoological Society of London|volume=42|issue=1|pages=111–23|url=https://www.biodiversitylibrary.org/page/28502198|doi=10.1111/j.1096-3642.1874.tb02459.x}}</ref> Urless N. Lanham observed in 1947 that frigatebirds bore some skeletal characteristics more in common with [[Procellariiformes]] than Pelecaniformes, though concluded they still belonged in the latter group (as suborder Fregatae), albeit as an early offshoot.<ref>{{cite journal |author=Lanham, Urless N. |journal=The Auk | volume=64|issue=1|pages=65–70 |year=1947|title= Notes on the phylogeny of the Pelecaniformes |url=https://sora.unm.edu/sites/default/files/journals/auk/v064n01/p0065-p0070.pdf |doi=10.2307/4080063|jstor=4080063 }}</ref> Martyn Kennedy and colleagues derived a [[cladogram]] based on behavioural characteristics of the traditional Pelecaniformes, calculating the frigatebirds to be more divergent than pelicans from a core group of gannets, [[darters]] and cormorants, and [[tropicbirds]] the most distant lineage.<ref>{{cite journal|last=Kennedy|first=Martyn |author2=Spencer, Hamish G. |author3=Gray, Russell D.|date=1996|title=Hop, step and gape: do the social displays of the Pelecaniformes reflect phylogeny?|journal=Animal Behaviour|volume=51|issue=2|pages=273–91|url=http://academic.brooklyn.cuny.edu/biology/jbasil/documents/Pelicanslecture2.pdf | doi=10.1006/anbe.1996.0028|s2cid=53202305 }}</ref> The classification of this group as the traditional Pelecaniformes, united by feet that are [[Bird feet and legs#Webbing and lobation|totipalmate]] (with all four toes linked by webbing) and the presence of a gular pouch, persisted until the early 1990s.<ref name="Hedges94">{{cite journal|author1=Hedges, S. Blair |author2=Sibley, Charles G. |year=1994|title=Molecules vs. morphology in avian evolution: the case of the "pelecaniform" birds|journal=PNAS|volume=91|issue=21|pages=9861–65|doi=10.1073/pnas.91.21.9861|pmid=7937906 |pmc=44917|bibcode=1994PNAS...91.9861H |doi-access=free }}</ref> The [[DNA–DNA hybridization]] studies of [[Charles Sibley]] and [[Jon Edward Ahlquist]] placed the frigatebirds in a lineage with [[penguin]]s, [[loon]]s, [[petrel]]s and [[albatross]]es.<ref>{{cite book|last=Sibley|first=Charles Gald|author2=Ahlquist, Jon Edward|title=Phylogeny and classification of birds|publisher=Yale University Press|location=New Haven, Connecticut|date=1990|isbn=978-0-300-04085-2}}</ref> Subsequent genetic studies place the frigatebirds as a [[sister group]] to the group [[Suloidea]], which comprises the gannets and boobies, cormorants and darters.<ref name = "Hackett2008">{{cite journal| last1 =  Hackett| first1 = Shannon J.| last2 = Kimball | first2 = Rebecca T.| last3 = Reddy | first3 = Sushma| last4 = Bowie | first4 = Rauri C. K.| last5 = Braun | first5 = Edward L.| last6 = Braun | first6 = Michael J.| last7 = Chojnowski | first7 = Jena L.| last8 = Cox | first8 = W. Andrew| last9 = Han | first9 = Kin-Lan| last10 =  Harshman | first10 =  John| last11 =  Huddleston | first11 =  Christopher J.| last12 =  Marks | first12 =  Ben D.| last13 =  Miglia | first13 =  Kathleen J.| last14 =  Moore | first14 =  William S.| last15 =  Sheldon | first15 =  Frederick H.| last16 =  Steadman | first16 =  David W.| last17 =  Witt | first17 =  Christopher C.| last18 =  Yuri | first18 =  Tamaki | title = A phylogenomic study of birds reveals their evolutionary history| journal = Science| date = 2008| volume = 320| issue = 5884| pages = 1763–68| doi = 10.1126/science.1157704| pmid =  18583609| bibcode = 2008Sci...320.1763H| s2cid = 6472805| url = http://www.sciencemag.org/cgi/content/abstract/320/5884/1763| url-access = subscription}}</ref><ref name=smith/> Microscopic analysis of eggshell structure by Konstantin Mikhailov in 1995 found that the eggshells of frigatebirds resembled those of other Pelecaniformes in having a covering of thick microglobular material over the crystalline shells.<ref>{{cite journal |last=Mikhailov |first=Konstantin E. |title=Eggshell structure in the shoebill and pelecaniform birds: comparison with hamerkop, herons, ibises and storks |journal=Canadian Journal of Zoology |year=1995 |issue=9 |volume=73 |pages= 1754–70 |doi=10.1139/z95-207 |bibcode=1995CaJZ...73.1754M }}</ref>

Molecular studies have consistently shown that [[pelican]]s, the namesake family of the Pelecaniformes, are actually more closely related to [[heron]]s, [[Threskiornithidae|ibises and spoonbills]], the [[hamerkop]] and the [[shoebill]] than to the remaining species. In recognition of this, the [[order (biology)|order]] comprising the frigatebirds and Suloidea was renamed [[Suliformes]] in 2010.<ref>{{cite journal| last1=Chesser  | first1=R. Terry  | last2=Banks | first2=Richard C. | last3=Barker | first3=F. Keith  | last4=Cicero | first4=Carla  | last5=Dunn | first5=Jon L. | last6=Kratter | first6=Andrew W. | last7=Lovette | first7=Irby J. | last8=Rasmussen | first8=Pamela C. | last9=Remsen  | first9=J.V. Jr | last10=Rising | first10=James D. | last11=Stotz  | first11=Douglas F. | last12=Winker  | first12=Kevin | year=2010 | title=Fifty-First Supplement to the American Ornithologists' Union Check-List of North American Birds |journal=The Auk |volume=127 | issue= 3 |pages= 726–44|doi=10.1525/auk.2010.127.3.726| s2cid=86363169 | url=https://zenodo.org/record/1236285 | doi-access=free }}</ref><ref>{{cite web|url=http://www.worldbirdnames.org/updates/archives/taxonomy-version-2/|title=Taxonomy Version 2|work=IOC World Bird List: Taxonomy Updates – v2.6 (23 October 2010) |year=2010|access-date=29 November 2014}}</ref>

In 1994, the family name Fregatidae, cited as described in 1867 by French naturalists [[Côme-Damien Degland]] and [[Zéphirin Gerbe]], was [[Conserved name|conserved]] under Article 40(b) of the [[International Code of Zoological Nomenclature]] in preference to the 1840 description Tachypetidae by [[Johann Friedrich von Brandt]]. This was because the genus names ''Atagen'' and ''Tachypetes'' had been [[Synonym (taxonomy)|synonymised]] with ''Fregata'' before 1961, resulting in the aligning of family and genus names.<ref>{{cite book | last=Bock | first=Walter J. | year=1994 | title=History and nomenclature of avian family-group names | series=Bulletin of the American Museum of Natural History Issue 222 | pages=131, 166 | hdl=2246/830 }}</ref>

===Fossil record===
[[File:Limnofregata azygosternon.jpg|thumb|right|Fossil of Eocene species ''Limnofregata azygosternon'']]
The [[Eocene]] frigatebird genus ''[[Limnofregata]]'' comprises birds whose fossil remains were recovered from prehistoric freshwater environments, unlike the marine preferences of their modern-day relatives. They had shorter less-hooked bills and longer legs, and longer slit-like nasal openings.<ref name="mayr">{{cite book |last=Mayr |first=Gerald |title=Paleogene Fossil Birds |publisher=Springer Science & Business Media |location=New York|date=2009 |pages=63–64 |isbn=978-3-540-89628-9 |url=https://books.google.com/books?id=P_TB72RBLLMC&q=Limnofregata&pg=PA63}}</ref><!-- cites previous two sentences --> Three species have been described from fossil deposits in the western United States, two—''L. azygosternon'' and ''L. hasegawai''—from the [[Green River Formation]] (48–52 million years old) and one—''L. hutchisoni''—from the [[Wasatch Formation]] (between 53 and 55 million years of age).<ref name="stidham">{{cite journal|last=Stidham|first=Thomas A.| year=2014 |title=A new species of ''Limnofregata'' (Pelecaniformes: Fregatidae) from the Early Eocene Wasatch Formation of Wyoming: implications for palaeoecology and palaeobiology | journal=Palaeontology | pages=1–11|doi=10.1111/pala.12134 | volume=58|issue=2|s2cid=85200173 |doi-access=free}}</ref> Fossil material indistinguishable from living species dating to the [[Pleistocene]] and [[Holocene]] has been recovered from [[Ascension Island]] (for ''F. aquila''),<ref>{{cite journal|last=Ashmole | first=Nelson Philip |year=1963|title= Sub-fossil bird remains on Ascension Island | journal=Ibis | volume= 103 | issue=3 | pages=382–89 | doi=10.1111/j.1474-919X.1963.tb06761.x }}</ref> [[Saint Helena|Saint Helena Island]],<ref>{{cite journal|last=Olson | first=Storrs L. |year= 1975|title= Paleornithology of St. Helena Island, South Atlantic Ocean | journal=Smithsonian Contributions to Paleobiology | volume= 23 | issue=23 | pages= 1–49 | url=http://www.sil.si.edu/smithsoniancontributions/paleobiology/pdf_lo/SCtP-0023.pdf | doi=10.5479/si.00810266.23.1}}</ref> both in the southern Atlantic Ocean, and also from various islands in the Pacific Ocean (for ''F. minor'' and ''F. ariel'').<ref>{{cite journal|last=James | first=Helen F.  |year=1987|title= A late Pleistocene avifauna from the island of Oahu, Hawaiian Islands |journal=Documents des Laboratories de Géologie, Lyon|volume= 99| pages=221–30 | url=https://repository.si.edu/bitstream/handle/10088/11424/vz_james-87-documlabgeollyon-pleistocene_oahu.pdf?sequence=1}}</ref><ref>{{cite book |last=Steadman |first=David W. |year=2006 |title=Extinction and biogeography of tropical Pacific birds |publisher=University of Chicago Press |location=Chicago, Illinois |isbn=978-0-226-77142-7 |url=https://books.google.com/books?id=vBZXJQ3HDg0C&q=fregata}}</ref> A [[tarsometatarsus]] and [[pedal phalanx]] from the [[Lower Eocene]] [[London Clay]] of the [[Walton-on-the-Naze]] resembles ''Limnofregata'', but being notably larger and distinct in other ways, was tentatively referred to ''Marinavis longirostris'' due to similar stratigraphy, geography, size, and presumed frigatebird affinities.<ref>{{Cite journal |last1=Mayr |first1=Gerald |last2=Kitchener |first2=Andrew |date=2024 |title=A large frigatebird-like tarsometatarsus from the London Clay of Walton-on-the-Naze (Essex, UK) may shed light on the affinities of a poorly known early Eocene seabird taxon |url=https://www.app.pan.pl/article/item/app011692024.html |journal=Acta Palaeontologica Polonica |volume=69 |doi=10.4202/app.01169.2024|doi-access=free }}</ref>

A [[cladistics|cladistic]] study of the skeletal and bone morphology of the classical Pelecaniformes and relatives found that the frigatebirds formed a [[clade]] with ''Limnofregata''. Birds of the two genera have 15 [[cervical vertebrae]], unlike almost all other [[Ciconiiformes]], Suliformes and Pelecaniformes, which have 17. The age of ''Limnofregata'' indicates that these lineages had separated by the Eocene.<ref name=smith>{{cite journal | last= Smith | first= Nathan D. | year=2010 | title= Phylogenetic analysis of Pelecaniformes (Aves) based on osteological data: Implications for waterbird phylogeny and fossil calibration studies | journal= PLOS ONE | volume=5 | issue = 10 | article-number= e13354 | doi = 10.1371/journal.pone.0013354 | pmid=20976229 | pmc=2954798| bibcode= 2010PLoSO...513354S | doi-access= free }}</ref><!-- cites previous 4 sentences --><!-- {{cite journal | last1=Kennedy | first1=Martyn | last2=Spencer | first2=Hamish G. | year=2004 | title=Phylogenies of the frigatebirds (Fregatidae) and tropicbirds (Phaethonidae), two divergent groups of the traditional order Pelecaniformes, inferred from mitochondrial DNA sequences | journal=Molecular Phylogenetics and Evolution | volume=31 | issue=1 | pages=31–38 | doi=10.1016/j.ympev.2003.07.007 | pmid=15019606}} -->

===Living species and infrageneric classification===
{{Cladogram|title=Frigatebird phylogeny<ref name=kennedy04/>
|caption=
|align=right
|cladogram={{Clade| style=font-size:90%;line-height:100%;width:400px;
   |1={{clade
      |1=[[Lesser frigatebird]] (''Fregata ariel'')
      |2={{clade
         |1={{clade
            |1=[[Christmas frigatebird]] (''Fregata andrewsi'')
            |2=[[Great frigatebird]] (''Fregata minor'')
            }}
         |2={{clade
            |1=[[Ascension frigatebird]] (''Fregata aquila'')
            |2=[[Magnificent frigatebird]] (''Fregata magnificens'')
            }}
         }}
      }}
   }}
}}
The [[type species]] of the genus is the  [[Ascension frigatebird]] (''Fregata aquila'').<ref name="AFD">{{cite web|url=http://www.environment.gov.au/topics/science-and-research/abrs/databases-and-online-resources/taxa/Fregata|archive-url=https://web.archive.org/web/20141205002927/http://www.environment.gov.au/topics/science-and-research/abrs/databases-and-online-resources/taxa/Fregata|archive-date=2014-12-05 |title=Genus ''Fregata'' Lacépède, 1799 |last=Australian Biological Resources Study|date=29 July 2014 |work=Australian Faunal Directory|publisher=Department of the Environment, Water, Heritage and the Arts, Australian Government|access-date=30 November 2014|location=Canberra, Australian Capital Territory}}</ref> For many years, the consensus was to recognise only two species of frigatebird, with larger birds as ''F. aquila'' and smaller as ''F. ariel''. In 1914 the Australian ornithologist [[Gregory Mathews]] delineated five species, which remain valid.<ref name=kennedy04>{{cite journal | last1=Kennedy | first1=Martyn | last2=Spencer | first2=Hamish G. | year=2004 | title=Phylogenies of the frigatebirds (Fregatidae) and tropicbirds (Phaethonidae), two divergent groups of the traditional order Pelecaniformes, inferred from mitochondrial DNA sequences | journal=Molecular Phylogenetics and Evolution | volume=31 | issue=1 | pages=31–38 | doi=10.1016/j.ympev.2003.07.007 | pmid=15019606 | bibcode=2004MolPE..31...31K }}</ref><ref>{{cite journal | last=Mathews | first=Gregory M. | author-link=Gregory Mathews | year=1914 | title=On the species and subspecies of the genus ''Fregata'' | journal=Australian Avian Record | volume=2 | issue=6 | pages=117–21 | url=https://www.biodiversitylibrary.org/page/34804723 }}</ref> Analysis of [[Ribosomal DNA|ribosomal]] and [[mitochondrial DNA]] indicated that the five species had diverged from a common ancestor only recently—as little as 1.5 million years ago. There are two species pairs, the great and Christmas Island frigatebirds, and the magnificent and Ascension frigatebirds, while the fifth species, the lesser frigatebird, is an early offshoot of the common ancestor of the other four species.<ref name=kennedy04/> Two subspecies of the magnificent, three subspecies of the lesser and five subspecies of the great frigatebird are recognised.<ref>{{Cite web |title=Storks, frigatebirds, boobies, darters, cormorants – IOC World Bird List |url=https://www.worldbirdnames.org/new/bow/storks/ |access-date=2022-05-09 |language=en-US}}</ref>British-Canadian ornithologist [[Anthony W. Diamond|Antony W. Diamond]] conducted some of the earliest ecological studies of frigatebirds, examining their breeding colonies''',''' feeding ecology''',''' and parental behavior on tropical islands.<ref>{{Cite journal |last=Diamond |first=Antony W. |last2=Schreiber |first2=E. A. |date=2020 |title=Magnificent Frigatebird (Fregata magnificens), version 1.0 |url=https://birdsoftheworld.org/bow/species/magfri/cur/introduction |journal=Birds of the World |language=en |doi=10.2173/bow.magfri.01 |issn=2771-3105|url-access=subscription }}</ref>Diamond’s fieldwork in the Indian [[Ocean]] and the [[Seychelles]] provided key insights into frigatebird nesting density''',''' interspecific competition, and the influence of food availability on breeding success.<ref>{{Cite journal |last=Croxall |first=John P. |date=January 2023 |title=Frigatebirds Fregata: impacts of potential taxonomic change on population and conservation status |url=https://www.cambridge.org/core/journals/bird-conservation-international/article/abs/frigatebirds-fregata-impacts-of-potential-taxonomic-change-on-population-and-conservation-status/E07904C16A18ABF27ADF35FEF5EF5E52 |journal=Bird Conservation International |language=en |volume=33 |pages=e70 |doi=10.1017/S0959270923000229 |issn=0959-2709|url-access=subscription }}</ref> 
{{Clear}}

{| class="wikitable sortable"
| style="background:#d3d3a4; text-align:center;" colspan="4"|'''Living species of frigatebirds'''
|-
! Common and binomial names
! class="unsortable"| Image
! Description
! Range
|-
| [[Magnificent frigatebird]]<br />(''Fregata magnificens'')<br /><small>[[Gregory Mathews|Mathews]], 1914</small>
| [[File:Fregata magnificens -Galapagos, Ecuador -male-8 (1).jpg|120px]]
| With a body length of {{convert|89|-|114|cm|in|abbr=on}}, it is the largest species and has the longest bill. The adult male is all-black with a scarlet [[throat pouch]] that is inflated like a balloon in the breeding season. Although the feathers are black, the scapular feathers have a purple sheen, in contrast to the male [[great frigatebird]]'s green sheen. The female is brownish-black, but has a white breast and lower neck sides, a brown band on the wings, and a blueish-grey  eye-ring.<ref name=hbwmagnificens>{{cite book | last1=Orta | first1=Jaume | last2=Christie | first2=D.A. | last3=Garcia | first3=E.F.J. | last4=Boesman | first4=P. | year=2020 | chapter=Magnificent Frigatebird (''Fregata magnificens'') | editor1-last=del Hoyo | editor1-first=J. | editor2-last=Elliott | editor2-first=A. | editor3-last=Sargatal | editor3-first=Sargatal | editor4-last=Christie | editor4-first=D.A. | editor5-last=de Juana | editor5-first=E. | title=Handbook of the Birds of the World Alive | publisher=Lynx Edicions | doi=10.2173/bow.magfri.01 | s2cid=216360730 | place=Barcelona, Spain | chapter-url=http://www.hbw.com/node/52669 | access-date=27 May 2015 }}{{subscription required}}</ref>
| Widespread in the tropical [[Atlantic Ocean|Atlantic]], it breeds in [[bird colony|colonies]] in trees in [[Florida]], the Caribbean and [[Cape Verde Islands]], as well as along the Pacific coast of the Americas from Mexico to Ecuador, including the [[Galápagos Islands]].<ref name=iucnmagn/>
|-
| [[Ascension frigatebird]]<br />(''Fregata aquila'')<br /><small>([[Carl Linnaeus|Linnaeus]], 1758)</small>
| [[File:Male Frigatebird with chick Fregata aquila.jpg|120px]]
| Apart from its smaller size, the adult male is very similar to the magnificent frigatebird. The female is brownish black with a rusty brown mantle and chest, and normally lacks any white patches present on the front of female birds of other species. The occasional female observed with a white belly may be breeding before obtaining the full adult plumage.<ref name=hbwaquila>{{cite book | last1=Orta | first1=Jaume | last2=Christie | first2=D.A. | last3=Garcia | first3=E. F. J. | last4=Jutglar | first4=F. | last5=Boesman | first5=P. | year=2020 | chapter=Ascension Frigatebird (''Fregata aquila'') | editor1-last=del Hoyo | editor1-first=J. | editor2-last=Elliott | editor2-first=A. | editor3-last=Sargatal | editor3-first=Sargatal | editor4-last=Christie | editor4-first=D. A. | editor5-last=de Juana | editor5-first=E. | title=Handbook of the Birds of the World Alive | publisher=Lynx Edicions | doi=10.2173/bow.asifri1.01 | s2cid=242440790 | place=Barcelona, Spain | chapter-url=http://www.hbw.com/node/52667 | access-date=29 December 2014 }}{{subscription required}}</ref>
| Found on [[Boatswain Bird Island]] just off [[Ascension Island]] in the tropical Atlantic Ocean, having not bred on the main island since the 1800s.<ref name=iucnascension>{{cite iucn |author=BirdLife International |date=2018 |title=''Fregata aquila'' |volume=2018 |article-number=e.T22697728A132597828 |doi=10.2305/IUCN.UK.2018-2.RLTS.T22697728A132597828.en |access-date=12 November 2021}}</ref>
|-
| [[Christmas frigatebird]]<br />(''Fregata andrewsi'')<br /><small>Mathews, 1914</small>
| [[File:Christmas Island Frigatebird.JPG|120px]]
| The adult male is one of the frigatebird species with white on its belly—an egg shaped patch. It is larger with a longer bill than the related great frigatebird. Its upperparts are black with green metallic gloss on the mantle and scapulars. The female has dark upperparts with brown wing bars, a black head with white belly and white collar (sometimes incomplete) around its neck.<ref name=james>{{cite journal|last=James |first=David J. |year=2004 |title=Identification of Christmas Island, Great and Lesser Frigatebirds |journal=BirdingASIA |volume=1 |pages=22–38 |url=http://tanzaniabirds.net/articles/Frigatebird-ID-BirdingAsia.pdf |archive-url=https://web.archive.org/web/20141209090255/http://tanzaniabirds.net/articles/Frigatebird-ID-BirdingAsia.pdf |archive-date=2014-12-09 }}</ref>
| Breeds only on [[Christmas Island]] in the eastern Indian Ocean.<ref name=iucnxmas>{{cite iucn |author=BirdLife International |date=2018 |title=''Fregata andrewsi'' |volume=2018 |article-number=e.T22697742A132599384 |doi=10.2305/IUCN.UK.2018-2.RLTS.T22697742A132599384.en |access-date=12 November 2021}}</ref>
|-
| [[Great frigatebird]]<br />(''Fregata minor'')<br /><small>([[Johann Friedrich Gmelin|Gmelin]], 1789)</small>
| [[File:Male greater frigate bird displaying crop.jpg|120px]]
| The adult male has black upperparts with green metallic gloss on the mantle and scapulars. It is completely black underneath with subtle brown barring on the axillaries. The upperparts of the female are dark with lighter brown wing bars. Its head is black with a mottled throat and belly. The neck has a white collar.<ref name=james/>
| Found in tropical Indian and Pacific oceans, as well as one colony—[[Trindade and Martim Vaz]]—in the south Atlantic, generally where the water is warmer than {{convert|22|C|F}}, and breeding on islands and atolls with sufficient vegetation to nest in.<ref name=iucngrt/>
|-
| [[Lesser frigatebird]]<br />(''Fregata ariel'')<br /><small>([[George Robert Gray|G. R.Gray]], 1845)</small>
| [[File:Lesser frigatebird lei.jpg|120px]]
| With a body length of around {{convert|75|cm|in|abbr=on}}, it is the smallest species. The adult male has black upperparts with greenish to purple metallic gloss on the mantle and scapulars, and is black underneath except for bold white axillary spurs. The upperparts of the female are dark with lighter wing bars. The head is black while the belly and the neck collar are white.<ref name=james/>
| Tropical and subtropical waters across the Indian and Pacific Oceans. Atlantic race ''trinitatis'' was limited to  [[Trindade (island)|Trindade]], off Eastern Brazil but may now be extinct.<ref name=hbwariel>{{cite book| last1=Orta | first1=Jaume | last2=Garcia | first2=E.F.J. | last3=Kirwan | first3=G.M. | last4=Boesman | first4=P. | chapter=Lesser Frigatebird (''Fregata ariel'') | editor1-last=del Hoyo | editor1-first=J. | editor2-last=Elliott | editor2-first=A. | editor3-last=Sargatal | editor3-first=J. | editor4-last=Christie | editor4-first=D.A. | editor5-last=de Juana | editor5-first=E. | title=Handbook of the Birds of the World Alive | year=2020 | publisher=Lynx Edicions | doi=10.2173/bow.lesfri.01 | s2cid=216239853 | chapter-url=http://www.hbw.com/node/52671  | access-date=30 November 2014 }}{{subscription required}}</ref><ref name=alves>{{cite book | last1=Alves | first1=R.J.V. | last2=da Silva | first2=N.G. | last3=Aguirre-Muñoz | first3=A. | year=2011 | chapter=Return of endemic plant populations on Trindade Island, Brazil, with comments on the fauna | editor1-last=Veitch | editor1-first=CR | editor2-last=Clout | editor2-first=MN | editor3-last=Towns | editor3-first=DR | title=Island invasives: eradication and management: proceedings of the International Conference on Island Invasives | publisher=IUCN | place=Gland, Switzerland | oclc=770307954 | pages=259–263 | chapter-url=http://www.issg.org/pdf/publications/Island_Invasives/pdfHQprint/3Alves.pdf | access-date=2015-05-27 | archive-date=2016-03-05 | archive-url=https://web.archive.org/web/20160305021259/http://issg.org/pdf/publications/Island_Invasives/pdfHQprint/3Alves.pdf }}</ref>
|}

==Description==
[[File:Magnificent-Frigate-male.jpg|thumb|right|Male magnificent frigatebird in the Galapagos Islands]]
Frigatebirds are large, slender, mostly black-plumaged, seabirds, with the five species similar in appearance to each other. The largest species is the magnificent frigatebird, which reaches {{convert|114|cm|in|abbr=on}} in length, with three of the remaining four almost as large. The lesser frigatebird is substantially smaller, at around {{convert|71|cm|in|abbr=on}} long. Frigatebirds exhibit marked [[sexual dimorphism]]; females are larger and up to 25 percent heavier than males,<ref name=hbwFregatidae/><!-- cites previous 3.5 sentences --> and generally have white markings on their underparts.<ref name=BoB>{{cite book |title=Biology of Birds |author=Khanna, D. R. |year=2005 |publisher=Discovery Publishing House |isbn=978-81-7141-933-3 |location=New Delhi, India |pages=317–19 |url=https://books.google.com/books?id=fDblIChi7KwC&q=Ascension+frigatebird&pg=PA318}}</ref> Frigatebirds have short necks and long, slender, hooked bills.<ref name=hbwFregatidae/> Their long narrow wings (male wingspan can reach {{convert|2.3|m|ft}}) taper to points. Their wings have eleven [[Primary feathers|primary flight feathers]], with the tenth the longest and eleventh a vestigial feather only, and 23 [[Secondary feathers|secondaries]]. Their tails are deeply forked, though this is not apparent unless the tail is fanned.<ref name=obrien/> The tail and wings give them a distinctive 'W' silhouette in flight.<ref name=hbwFregatidae/> The legs and face are fully feathered. The totipalmate feet are short and weak; the webbing is reduced and part of each toe is free.<ref name=obrien/>

The bones of frigatebirds are markedly [[Skeletal pneumaticity|pneumatic]], making them very light and contributing only 5% to total body weight. The [[pectoral girdle]] is strong as its bones are fused. The pectoral muscles are well-developed, and weigh as much as the frigatebird's feathers—around half the body weight is made up equally of these muscles and feathers.<ref name=hbwFregatidae/><!-- cites previous 3 sentences --> The males have inflatable red-coloured throat pouches called gular pouches which they inflate to attract females during the mating season.<ref name=BoB/> The gular sac is, perhaps, the most striking frigatebird feature. These can deflate only slowly, so males that are disturbed will fly off with pouches distended for some time.<ref name=hbwFregatidae/><!-- cites previous two sentences -->

Frigatebirds remain in the air and do not settle on the ocean. They produce very little oil from their [[uropygial gland]]s, so their feathers would become sodden if they settled on the surface. In addition, with their long wings relative to body size, they would have great difficulty taking off again.<ref name=hbwFregatidae/>

==Distribution and habitat==
Frigatebirds are found over tropical oceans, and ride warm [[vertical draft|updrafts]] under [[cumulus cloud]]s. Their range coincides with availability of food such as [[flying fish]], and with the [[trade wind]]s, which provide the windy conditions that facilitate their flying.<ref name=hbwFregatidae/> They occur as rare [[Vagrancy (biology)|vagrant]]s to [[Temperate climate|temperate region]]s and are not found in polar latitudes. Adults are generally sedentary, remaining near the islands where they breed.<ref name=hbwFregatidae/><!-- cites previous two sentences --> However, male frigatebirds have been recorded dispersing great distances after departing a breeding colony—one male great frigatebird relocated from [[Europa Island]] in the Mozambique Channel to the [[Maldives]] {{convert|4400|km|mi|abbr=on}} away, and a male magnificent frigatebird flew {{convert|1400|km|mi|abbr=on}} from [[French Guiana]] to [[Trinidad]].<ref name="Weimerskirch 2006">{{cite journal|last1=Weimerskirch|first1=Henri|last2=Le Corre |first2=Matthieu |last3=Marsac |first3=Francis |last4=Barbraud |first4=Christophe |last5=Tostain |first5=Olivier |last6=Chastel |first6=Olivier |date=2006 |title=Postbreeding movements of frigatebirds tracked with satellite telemetry |journal=The Condor |volume=108 |issue=1|pages=220–25|doi=10.1650/0010-5422(2006)108[0220:PMOFTW]2.0.CO;2|s2cid=55434650 |doi-access=free }}</ref> In 2015, a magnificent frigatebird was spotted as far north as Michigan.<ref>{{cite web |last1=Engel |first1=Joshua |title=A tropical wanderer visits the Midwest |url=https://www.fieldmuseum.org/blog/tropical-wanderer-visits-midwest |publisher=Field Museum of Natural History |access-date=28 January 2022 |date=15 July 2015}}</ref> Great frigatebirds marked with [[bird ringing|wing tags]] on Tern Island in the [[French Frigate Shoals]] were found to regularly travel the {{convert|873|km|mi|abbr=on}} to [[Johnston Atoll]], although one was reported in [[Quezon City]] in the [[Philippines]]. Genetic testing seems to indicate that the species has fidelity to their site of hatching despite their high mobility.<ref name=Dearborn>{{cite journal | last1=Dearborn |first1=D. |last2=Anders |first2=A. |last3=Schreiber |first3=E. |last4=Adams |first4=R. |last5=Muellers |first5=U. |year=2003| title=Inter island movements and population differentiation in a pelagic seabird  |journal= Molecular Ecology |volume=12 |pages= 2835–43 |doi=10.1046/j.1365-294X.2003.01931.x |pmid=12969485 |issue=10|bibcode=2003MolEc..12.2835D |s2cid=18679093}}</ref> Young birds may disperse far and wide, with distances of up to {{convert|6000|km|mi|abbr=on}} recorded.<ref name=hbwFregatidae/>

==Behaviour and ecology==
[[File:Prachtfregattvogel MM01.jpg|left|thumb|Magnificent frigatebirds drinking freshwater]]
Having the largest wing-area-to-body-weight ratio of any bird, frigatebirds are essentially aerial.<ref name=hbwFregatidae/> This allows them to soar continuously and only rarely flap their wings. One great frigatebird, being tracked by satellite in the Indian Ocean, stayed aloft for two months. They can fly higher than 4,000 meters in freezing conditions.<ref>{{ cite journal | last1=Weimerskirch | first1=H. | last2=Bishop | first2=C. | last3=Jeanniard-du-Dot | first3=T. | last4=Prudor | first4=A. | last5=Sachs | first5=G. | year=2016 | title=Frigate birds track atmospheric conditions over months-long transoceanic flights | journal=Science | volume=353 | issue=6294 | pages=74–78 | doi=10.1126/science.aaf4374 | pmid=27365448| bibcode=2016Sci...353...74W | s2cid=206648100 | url=https://research.bangor.ac.uk/portal/en/researchoutputs/frigate-birds-track-atmospheric-conditions-over-monthslong-transoceanic-flights(7871f444-35c6-4ce1-a788-df0bf321e7dd).html }}</ref> Like [[Swift (bird)|swift]]s they are able to spend the night on the wing, but they will also return to an island to roost on trees or cliffs.<ref name=weimerskirch03>{{cite journal | last1=Weimerskirch | first1=Henri | last2=Chastel | first2=Olivier | last3=Barbraud | first3=Christophe | last4=Tostain | first4=Olivier | year=2003 | title=Frigatebirds ride high on thermals | journal=Nature | volume=421 | pages=333–34 | url=http://www.cebc.cnrs.fr/publipdf/2003/WNat421.pdf | doi=10.1038/421333a | pmid=12540890 | issue=6921 | s2cid=4357404 | access-date=2014-12-23 | archive-date=2018-09-21 | archive-url=https://web.archive.org/web/20180921192153/http://www.cebc.cnrs.fr/publipdf/2003/WNat421.pdf }}</ref><!-- cites previous 2 sentences --> Field observations in the [[Mozambique Channel]] found that great frigatebirds could remain on the wing for up to 12 days while foraging.<ref>{{cite journal | last1=Weimerskirch | first1=Henri | last2=Le Corre | first2=Matthieu  | last3=Jaquemet | first3=Sébastien  | last4=Potier | first4=Michel  | last5=Marsac | first5=Francis | year=2004 | title=Foraging strategy of a top predator in tropical waters: great frigatebirds in the Mozambique Channel | journal=Marine Ecology Progress Series | volume=275 | pages=297–308 | doi=10.3354/meps275297 | bibcode=2004MEPS..275..297W | url=https://www.int-res.com/articles/meps2004/275/m275p297.pdf | doi-access=free }}</ref> Highly adept, they use their forked tails for steering during flight and make strong deep wing-beats,<ref name=obrien/> though not suited to flying by sustained flapping. Frigatebirds bathe and clean themselves in flight by flying low and splashing at the water surface before preening and scratching afterwards.<ref name=hbwFregatidae/><!-- cites previous 2 sentences --> Conversely, frigatebirds do not swim and with their short legs cannot walk well or take off from the sea easily.<ref name=obrien/>

According to a study in the journal ''Nature Communications'', scientists attached an [[accelerometer]] and an [[electroencephalogram]] testing device on nine great frigatebirds to measure if they slept during flight. The study found the birds do sleep, but usually only using one hemisphere of the brain at a time and usually sleep while ascending at higher altitudes. The amount of time mid-air sleeping was less than an hour and always at night.<ref>{{cite news |last=Ferro |first=Shaunacy |url=http://mentalfloss.com/article/84220/can-birds-sleep-mid-flight-yes-new-study-confirms |title=Can Birds Sleep Mid-Flight? Yes, a New Study Confirms |work=[[Mental Floss]] |date=2016-08-04 |access-date=2019-09-19 }}</ref>

The average life span is unknown but in common with seabirds such as the [[wandering albatross]] and [[Leach's storm petrel]], frigatebirds are long-lived. In 2002, 35 ringed great frigatebirds were recovered on [[Tern Island (Hawaii)|Tern Island]] in the [[Hawaiian Islands]]. Of these ten were older than 37 years and one was at least 44 years of age.<ref name=juola>{{cite journal | last1=Juola | first1=Frans A. | last2=Haussmann | first2=Mark F. | last3=Dearborn | first3=Donald C. | last4=Vleck | first4=Carol M. | year=2006 | title=Telomere shortening in a long-lived marine bird: cross-sectional analysis and test of an aging tool | journal=The Auk | volume=123 | issue=3 | pages=775–83 | doi=10.1642/0004-8038(2006)123[775:TSIALM]2.0.CO;2 | s2cid=46907175 | url=http://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1009&context=eeob_las_pubs | doi-access=free }}</ref>

Despite having dark plumage in a tropical climate, frigatebirds have found ways not to overheat—particularly as they are exposed to full sunlight when on the nest. They ruffle feathers to lift them away from the skin and improve air circulation, and can extend and upturn their wings to expose the hot undersurface to the air and lose heat by evaporation and convection. Frigatebirds also place their heads in the shade of their wings, and males frequently flutter their gular pouches.<ref name=hbwFregatidae/><!-- cites previous 3 sentences -->

Unlike most seabirds, frigatebirds are [[thermal soaring|thermal soarers]], using thermals to glide.<ref>{{cite journal | url=https://www.biorxiv.org/content/10.1101/2020.10.31.354605v1.full | doi=10.1093/pnasnexus/pgac023|biorxiv=10.1101/2020.10.31.354605 | title=Soaring styles of extinct giant birds and pterosaurs |journal= PNAS Nexus | year=2020 | last1=Goto | first1=Yusuke | last2=Yoda | first2=Ken | last3=Weimerskirch | first3=Henri | last4=Sato | first4=Katsufumi | article-number=pgac023| s2cid=226263538|doi-access=free | pmid=36712794| pmc=9802081 }}</ref><ref>{{cite journal | jstor=27838346 | title=Thermal Soaring of Birds | last1=Cone | first1=Clarence D. | journal=American Scientist | year=1962 | volume=50 | issue=1 | pages=180–209 }}</ref> This is in contrast to birds like albatrosses, which are [[dynamic soaring|dynamic soarers]], using winds produced by the waves to stay aloft.

[[File:Soaring styles.png|thumb|Soaring styles in extinct and extant flyers. Frigatebirds are marked as thermal soarers.]]

===Breeding behaviour===
{{See also|Seabird breeding behavior}}
[[File:Fregata magnificens -Galapagos, Ecuador -male-8.jpg|thumb|right|Magnificent frigatebird male breeding display]]
Frigatebirds typically breed on remote oceanic islands, generally in colonies of up to 5000 birds. Within these colonies, they most often nest in groups of 10 to 30 (or rarely 100) individuals.<ref name=obrien/> Breeding can occur at any time of year, often prompted by commencement of the dry season or plentiful food.<ref name=hbwFregatidae/>

Frigatebirds have the most elaborate mating displays of all seabirds. The male birds take up residence in the colony in groups of up to thirty individuals.<ref name=hbwFregatidae/> They display to females flying overhead by pointing their bills upwards, inflating their red throat pouches and vibrating their outstretched wings, showing the lighter wing undersurfaces in the process. They produce a drumming sound by vibrating their bills together and sometimes give a whistling call.<ref name=obrien/> The female descends to join a male she has chosen and allows him to take her bill in his. The pair also engages in mutual "head-snaking".<ref name=hbwFregatidae/>

After copulation it is generally the male who gathers sticks and the female that constructs the loosely woven nest. The nest is subsequently covered with (and cemented by) [[guano]]. Frigatebirds prefer to nest in trees or bushes, though when these are not available, they will nest on the ground. A single white egg that weighs up to 6–7% of mother's body mass is laid, and is [[Egg incubation|incubated]] in turns by both birds for 41 to 55 days. The [[altricial]] chicks are naked on hatching and develop a white down. They are continuously guarded by the parents for the first 4–6 weeks and are fed on the nest for 5–6 months.<ref name=obrien/> Both parents take turns feeding for the first three months, after which the male's attendance trails off, leaving the mother to feed the young for another six to nine months on average.<ref name=hbwFregatidae/> The chicks feed by reaching their heads in their parents' throat and eating the partially regurgitated food. It takes so long to rear a chick that frigatebirds generally breed only every other year.<ref name=obrien/>
[[File:Seabird colony.JPG|thumb|right|Seabird colony with great frigatebirds, [[red-tailed tropicbird]], [[red-footed booby|red-footed boobies]], sooty terns and [[black noddy|black noddies]], French Frigate Shoals]]
The duration of parental care in frigatebirds is among the longest for birds, rivalled by only the [[southern ground hornbill]] and some large [[Accipitridae|accipitrids]].<ref>{{cite book |last1=Skutch |first1=Alexander Frank |last2=Gardner |first2=Dana (illustrator) |year=1987 |title=Helpers at Birds' Nests: a worldwide survey of cooperative breeding and related behaviour |pages=[https://archive.org/details/helpersatbirdsne00skut_0/page/69 69–71] |place=Iowa City |publisher=University of Iowa Press |isbn=0-87745-150-8 |url-access=registration |url=https://archive.org/details/helpersatbirdsne00skut_0/page/69 }}</ref> Frigatebirds take many years to reach sexual maturity. A study of great frigatebirds in the Galapagos Islands found that they bred only after they have acquired the full adult plumage. This was attained by female birds when they were eight to nine years of age and by male birds when they were ten to eleven years of age.<ref name=valle>{{cite journal | last1=Valle | first1=Arlos A. | last2=de Vries | first2=Tjitte | last3=Hernández | first3=Cecilia  | year=2006 | title=Plumage and sexual maturation in the Great frigatebird ''Fregata minor'' in the Galapagos Islands | journal=Marine Ornithology | volume=34 | pages=51–59 | doi=10.5038/2074-1235.34.1.682 | url=http://www.marineornithology.org/PDF/34_1/34_1_51-59.pdf }}</ref>

===Feeding===
[[File:Frigate sooty.JPG|right|thumb|An immature great frigatebird snatching a [[sooty tern]] chick]]
Frigatebirds' feeding habits are [[Pelagic birds|pelagic]], and they may forage up to 500&nbsp;km (310&nbsp;mi) from land. They do not land on the water but snatch prey from the ocean surface using their long, hooked [[beak|bills]].<ref name=obrien>{{cite book |last1=O'Brien |first1=Rory M. |year=1990 |chapter=Family Fregatidae frigatebirds |editor1-last=Marchant |editor1-first=S. |editor2-last=Higgins |editor2-first=P.G. |title=Handbook of Australian, New Zealand & Antarctic Birds. Volume 1: Ratites to ducks; Part B, Australian pelican to ducks |place=Melbourne, Victoria |publisher=Oxford University Press |isbn=978-0-19-553068-1 |page=912 |chapter-url=http://nzbirdsonline.org.nz/sites/all/files/142_Great%20Frigatebird.pdf#2 |archive-date=2015-01-27 |access-date=2014-12-24 |archive-url=https://web.archive.org/web/20150127001914/http://www.nzbirdsonline.org.nz/sites/all/files/142_Great%20Frigatebird.pdf#2 }}</ref> They catch mainly small fish such as [[flying fish]], particularly the genera ''[[Exocoetus]]'' and ''[[Cypselurus]]'', that are driven to the surface by predators such as [[tuna]] and [[dolphinfish]],<ref name=weimerskirch03/> but they will also eat [[cephalopod]]s, particularly [[squid]].<ref name=obrien/> [[Menhaden]] of the genus ''[[Brevoortia]]'' can be an important prey item where common, and [[jellyfish]] and larger [[plankton]] are also eaten. Frigatebirds have learned to follow fishing vessels and take fish from holding areas.<ref name=hbwFregatidae/> Conversely tuna fishermen fish in areas where they catch sight of frigatebirds due to their association with large marine predators.<ref name="Weimerskirch 2010">{{cite journal|last1=Weimerskirch|first1=Henri|last2=Le Corre |first2=Matthieu |last3=Kai |first3=Emilie Tew |last4=Marsac |first4=Francis|date=2010|title=Foraging movements of great frigatebirds from Aldabra Island: Relationship with environmental variables and interactions with fisheries|journal=Progress in Oceanography|volume=86|issue=1–2|pages=204–13|doi=10.1016/j.pocean.2010.04.003|bibcode=2010PrOce..86..204W}}</ref> Frigatebirds also at times prey directly on eggs and young of other seabirds, including boobies, petrels, [[shearwater]]s and terns, in particular the [[sooty tern]].<ref name=hbwFregatidae/>

Frigatebirds will rob  of their catch other [[seabird]]s such as boobies, particularly the [[red-footed booby]], [[tropicbird]]s, shearwaters, petrels, terns, [[gull]]s and even [[osprey]]s, using their speed and manoeuvrability to outrun and harass their victims until they regurgitate their stomach contents. They may either assail their targets after they have caught their food or circle high over seabird colonies waiting for parent birds to return laden with food.<ref name=hbwFregatidae/> Although frigatebirds are renowned for their [[Kleptoparasitism|kleptoparasitic feeding behaviour]], kleptoparasitism is not thought to play a significant part of the diet of any species, and is instead a supplement to food obtained by hunting.<ref name = "Burger">{{cite book | last1=Schreiber | first1=Elizabeth A. | last2=Burger |first2=Joanne |year=2001 |title=Biology of Marine Birds | place=Boca Raton, Florida | publisher=CRC Press | isbn=0-8493-9882-7}}</ref> A study of great frigatebirds stealing from [[masked booby|masked boobies]] estimated that the frigatebirds could obtain at most 40% of the food they needed, and on average obtained only 5%.<ref>{{cite journal | last1=Vickery | first1=J.A.  | last2=Brooke | first2=M. de L. |year=1994 |title=The kleptoparasitic interactions between Great Frigatebirds and Masked Boobies on Henderson Island, South Pacific | journal=Condor |volume=96 | issue=2 | pages=331–40 | jstor=1369318 | url=http://sora.unm.edu/sites/default/files/journals/condor/v096n02/p0331-p0340.pdf |doi=10.2307/1369318}}</ref>

Unlike most other seabirds, frigatebirds drink freshwater when they come across it, by swooping down and gulping with their bills.<ref name=hbwFregatidae/>

===Parasites===
Frigatebirds are unusual among seabirds in that they often carry blood parasites. Blood-borne [[protozoa]] of the genus ''[[Haemoproteus]]'' have been recovered from four of the five species.<ref>{{cite journal |author1=Merino, Santiago |author2=Hennicke, Janos |author3=Martínez, Javier |author4=Ludynia, Katrin |author5=Torres, Roxana |author6=Work, Thierry M. |author7=Stroud, Stedson |author8=Masello, Juan F. |author9=Quillfeldt, Petra |date=2012 |title=Infection by Haemoproteus parasites in four species of frigatebirds and the description of a new species of Haemoproteus (Haemosporida: Haemoproteidae) |journal=Journal of Parasitology |volume=98 |issue=2 |pages=388–97 |url=https://www.nwhc.usgs.gov/hfs/Globals/Products/MerinoEA2012HaemoproteusFrigates.pdf |doi=10.1645/GE-2415.1 |pmid=21992108 |bibcode=2012JPara..98..388M |s2cid=3846342 |access-date=2015-05-14 |archive-url=https://web.archive.org/web/20161210091542/https://www.nwhc.usgs.gov/hfs/Globals/Products/MerinoEA2012HaemoproteusFrigates.pdf |archive-date=2016-12-10 }}</ref> Bird lice of the [[ischnocera]]n genus ''[[Pectinopygus]]'' and [[amblycera]]n genus ''[[Colpocephalum]]'' and species ''[[Fregatiella aurifasciata]]'' have been recovered from magnificent and great frigatebirds of the Galapagos Islands. Frigatebirds tended to have more parasitic lice than did boobies analysed in the same study.<ref>{{cite journal|author1=Rivera-Parra, Jose L. |author2=Levin, Iris I. |author3=Parker, Patricia G. |date=2014|title=Comparative ectoparasite loads of five seabird species in the Galapagos Islands|journal=Journal of Parasitology|volume=100|issue=5|pages=569–77|doi=10.1645/12-141.1|pmid=24911632|s2cid=9735489 }}</ref>

A heavy chick mortality at a large and important colony of the magnificent frigatebird, located on [[Îles du Connétable|Île du Grand Connétable]] off French Guiana, was recorded in summer 2005. Chicks showed nodular skin lesions, feather loss and corneal changes, with around half the year's progeny perishing across the colony. An [[Alphaherpesvirinae|alphaherpesvirus]] was isolated and provisionally named ''Fregata magnificens'' herpesvirus, though it was unclear whether it caused the outbreak or affected birds already suffering malnutrition.<ref name="de Thoisy">{{cite journal|author1=de Thoisy, Benoit |author2=Lavergne, Anne |author3=Semelin, Julien |author4=Pouliquen, Jean-François |author5=Blanchard, Fabian |author6=Hansen, Eric |author7=Lacoste, Vincent |date=2009 |title=Outbreaks of disease possibly due to a natural avian herpesvirus infection in a colony of young magnificent frigatebirds (''Fregata magnificens'') in French Guiana|journal= Journal of Wildlife Diseases|volume=45|issue=3|pages=802–07|pmid=19617492 |doi=10.7589/0090-3558-45.3.802|s2cid=13466300 |url=https://archimer.ifremer.fr/doc/2009/publication-6811.pdf }}</ref>

==Status and conservation==

===Populations and threats===
Two of the five species are considered at risk.<ref name=hbwFregatidae/> In 2003, a survey of the four colonies of the critically endangered Christmas Island frigatebirds counted 1200 breeding pairs. As frigatebirds normally breed every other year, the total adult population was estimated to lie between 1800 and 3600 pairs. Larger numbers formerly bred on the island, but the clearance of breeding habitat during World War II and dust pollution from phosphate mining have contributed to the decrease.<ref name=iucnxmas/><ref name=james14>{{cite journal |last1=James |first1=David J. |last2=McAllan |first2=Ian A.W. |year=2014 |title=The birds of Christmas Island, Indian Ocean: A review |journal=Australian Field Ornithology |volume=31 |issue=Supplement |url=http://birdlife.org.au/documents/AFO-Christmas_Island_Supplement-2014-v2.pdf#64 |pages=S24 Table 3, S64–S67 |access-date=2015-05-15 |archive-date=2015-05-18 |archive-url=https://web.archive.org/web/20150518102319/http://birdlife.org.au/documents/AFO-Christmas_Island_Supplement-2014-v2.pdf#64 }}</ref> The population of the vulnerable Ascension frigatebird has been estimated at around 12,500 individuals.<ref name=ratcliffe08>{{cite journal |last1=Ratcliffe |first1=Norman |last2=Pelembe |first2=Tara  |last3=White | first3=Richard |year=2008 |title=Resolving the population status of Ascension Frigatebird ''Fregata aquila'' using a 'virtual ecologist' model |journal=Ibis |volume=150 |issue=2 |pages=300–306 |doi=10.1111/j.1474-919X.2007.00778.x |url=http://www.ascension-island.gov.ac/wp-content/uploads/2012/12/Ratcliffe-Pelembe-White-2008-Resolving-the-population-status-of-Ascension-frigatebird-Fregata-aquila-using-a-virtual-ecologist-model.-Ibis.pdf }}</ref> The birds formerly bred on Ascension Island itself, but the colonies were exterminated by [[feral cat]]s introduced in 1815. The birds continued to breed on a rocky outcrop just off the shore of the island. A program conducted between 2002 and 2004 eradicated the feral cats<ref>{{cite journal |last1=Ratcliffe |first1=Norman |last2=Bella |first2=Mike |last3=Pelembe |first3=Tara |last4=Boyle |first4=Dave |last5=Benjamin |first5=Raymond |last6=White |first6=Richard  |last7=Godley |first7=Brendan |last8=Stevenson  |first8=Jim  |last9=Sanders |first9=Sarah |year=2010 |title=The eradication of feral cats from Ascension Island and its subsequent recolonization by seabirds |journal=Oryx |volume=44 |issue=1 |pages=20–29 |doi=10.1017/S003060530999069X |url=http://www.ascension-island.gov.ac/wp-content/uploads/2012/12/Ratcliffe-et-al-2009-The-eradication-of-feral-cats-from-Ascension-Island-and-its-subsequent-recolonization-by-seabirds.pdf |doi-access=free}}</ref> and a few birds have returned to nest on the island.<ref>{{cite news |url=https://www.theguardian.com/environment/2012/dec/08/frigatebird-returns-to-ascension |last=McKie |first=Robin |title=Frigatebird returns to nest on Ascension for first time since Darwin |newspaper=[[The Observer]] |date=8 December 2012 |access-date=10 December 2012 }}</ref><ref>{{cite web |last=Fisher |first=Ian | date=23 January 2014  |title=Ascension frigatebird – the return continues |publisher=Royal Society for the Protection of Birds|url=http://www.rspb.org.uk/community/ourwork/b/biodiversity/archive/2014/01/23/ascension-frigatebird-the-return-continues.aspx |access-date=8 December 2014}}</ref>

The other three species are classified by the [[International Union for Conservation of Nature]] as being of ''Least Concern''. The populations of all three are large, with that of the magnificent frigatebird thought to be increasing,<ref name=iucnmagn>{{cite iucn |author=BirdLife International |date=2020 |title=''Fregata magnificens'' |volume=2020 |article-number=e.T22697724A168982712 |doi=10.2305/IUCN.UK.2020-3.RLTS.T22697724A168982712.en |access-date=12 November 2021}}</ref> while thatof the great and lesser frigatebird decreasing.<ref name=iucngrt>{{cite iucn |author=BirdLife International |date=2020 |title=''Fregata minor'' |volume=2020 |article-number=e.T22697733A163770613 |doi=10.2305/IUCN.UK.2020-3.RLTS.T22697733A163770613.en |access-date=12 November 2021}}</ref><ref name=iucnlssr>{{cite iucn |author=BirdLife International |date=2018 |title=''Fregata ariel'' |volume=2018 |article-number=e.T22697738A132598822 |doi=10.2305/IUCN.UK.2018-2.RLTS.T22697738A132598822.en |access-date=12 November 2021}}</ref> Monitoring populations of all species is difficult due to their movements across the open ocean and low reproductivity. The status of the Atlantic populations of the great and lesser frigatebirds are unknown and possibly extinct.<ref name=hbwFregatidae/>

As frigatebirds rely on large marine predators such as tuna for their prey, overfishing threatens to significantly impact on food availability and jeopardise whole populations.<ref name="Weimerskirch 2010"/> As frigatebirds nest in large dense colonies in small areas, they are vulnerable to local disasters that could wipe out the rare species or significantly impact the widespread ones.<ref name=hbwFregatidae/>

===Hunting===
In [[Nauru]], catching frigatebirds was an important tradition still practised to some degree. Donald W. Buden writes: "Birds typically are captured by slinging the weighted end of a coil of line in front of an approaching bird attracted to previously captured birds used as decoys. In a successful toss, the line becomes entangled about the bird's wing and bringing [sic] it to ground."<ref>{{cite journal |last=Buden |first=Donald W. |year=2008 |title=The birds of Nauru |journal=Notornis |volume=55 |pages=8–19 |doi=10.63172/767667oadncj |url=http://notornis.osnz.org.nz/system/files/Notornis_55_1_8.pdf |access-date=2014-06-06 |archive-date=2017-01-06 |archive-url=https://web.archive.org/web/20170106160018/http://notornis.osnz.org.nz/system/files/Notornis_55_1_8.pdf }}</ref> Marine birds including frigatebirds were once harvested for food on Christmas Island, but this practice ceased in the late 1970s.<ref name=james14/> Eggs and young of magnificent frigatebirds were taken and eaten in the Caribbean.<ref name=hbwFregatidae/> Great frigatebirds were eaten in the Hawaiian Islands and their feathers used for decoration.<ref>{{cite book |last=Barwell |first=Graham |title=Albatross |publisher=Reaktion Books |location=London, United Kingdom |date=2013 |page=68 |isbn=978-1-78023-214-0 |url=https://books.google.com/books?id=I5AOBQAAQBAJ&pg=PA68}}</ref>

==Cultural significance==
[[File:Nazca Frigate Bird from 062016 flamingo.jpg|thumb|The frigate bird painted in the [[Nazca Lines|Nazca desert]].]]
The frigate bird appears on the national [[Flag of Kiribati]]. The design is based on its former colonial [[Gilbert and Ellice Islands]] coat of arms. The bird also appears on the flag of [[Barbuda]], and is the national bird of [[Antigua and Barbuda]].<ref>{{ cite web| title=Our National Symbols | url=https://ab.gov.ag/detail_page.php?page=26 | publisher=Government of Antigua and Barbuda | access-date=25 November 2021 }}</ref>

There are anecdotal reports of tame frigatebirds being kept across Polynesia and Micronesia in the Pacific. A bird that had come from one island and had been taken elsewhere could be reliably trusted to return to its original home, hence would be used as a speedy way to relay a message there.<ref name=hbwFregatidae/> There is evidence of this practice taking place in the [[Gilbert Islands]] and [[Tuvalu]].<ref name="Lewis1994">{{cite book |last=Lewis |first=David |year=1994 |title=We, the Navigators: The Ancient Art of Landfinding in the Pacific |publisher=University of Hawaii Press |page=[https://archive.org/details/wenavigatorsanci0000lewi/page/208 208] |isbn=978-0-8248-1582-0 |url=https://archive.org/details/wenavigatorsanci0000lewi|url-access=registration }}</ref>

The great frigatebird was venerated by the [[Rapa Nui people]] on [[Easter Island]]; carvings of the birdman [[Tangata manu]] depict him with the characteristic hooked beak and throat pouch.<ref>{{cite book |last1=Kjellgren |first1=Eric |last2=Van Tilburg |first2=JoAnne |last3=Kaeppler |first3=Adrienne Lois |year=2001 |title=Splendid Isolation: Art of Easter Island |publisher=Metropolitan Museum of Art |location=New York, New York |pages=44–45 |isbn=978-1-58839-011-0 |url=https://books.google.com/books?id=YuRdI3s5NCYC&pg=PA45}}</ref> Its incorporation into local ceremonies suggests that the now-vanished species was extant there between the 1800s and 1860s.<ref>{{cite book |last=Fischer |first=Steven Roger |year=1967 |title=Rongorongo: The Easter Island Script: History, Traditions, Texts |publisher=Clarendon Press |location=Oxford, United Kingdom |series=Oxford studies in anthropological linguistics |volume=14 |page=489 |isbn=978-0-19-823710-5 |url=https://books.google.com/books?id=Tj16rYA5xK0C&pg=PA489}}</ref>

Maritime folklore around the time of European contact with the Americas held that frigatebirds were birds of good omen as their presence meant land was near.<ref name=hbwFregatidae/>

==See also==
* [[List of birds by flight speed]]

== Explanatory notes ==
{{notelist}}

== References ==
<references>
<ref name=hbwFregatidae>{{cite book |last1=Orta |first1=Jaume  |chapter=Family Fregatidae, Frigatebirds |editor1-last=del Hoyo | editor1-first=J |editor2-last=Elliott |editor2-first=A. |editor3-last=Sargatal |editor3-first=J. |editor4-last=Christie |editor4-first=D.A. | editor5-last=de Juana |editor5-first=E. |title=Handbook of the Birds of the World Alive |date=2020 |publisher=Lynx Edicions |doi=10.2173/bow.fregat1.01 |s2cid=242682341 |chapter-url=http://www.hbw.com/family/frigatebirds-fregatidae  |access-date=13 May 2015 }}{{subscription required}}</ref>
</references>

==External links==
{{Commons category|Fregata}}
* [http://ibc.lynxeds.com/family/frigatebirds-fregatidae Frigatebird videos, photos and sounds] on the Internet Bird Collection

{{Suliformes}}
{{Suliformes Genera|S.|state=collapsed}}
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[[Category:Fregata| ]]
[[Category:Fregatidae|Fregatidae]]
[[Category:Extant Ypresian first appearances]]
[[Category:Pleistocene animals of Africa]]
[[Category:Pleistocene animals of Asia]]
[[Category:Pleistocene animals of Oceania]]
[[Category:Pleistocene animals of South America]]
[[Category:Pleistocene birds of North America]]
[[Category:Pleistocene birds]]
[[Category:Seabirds]]
[[Category:Taxa named by Bernard Germain de Lacépède]]