skua

File:Skuas and Giant Petrel.jpgs (S. antarcticus) and a southern giant petrel (Macronectes giganteus) fighting over a dead Antarctic fur seal]]

Outside the breeding season, skuas take fish, offal, and carrion. Many practice kleptoparasitism, which comprises up to 95% of the feeding methods of wintering skuas, by chasing gulls, terns and other seabirds to steal their catches, regardless of the size of the species attacked (up to three times heavier than the attacking skua). Larger species, such as the great skua, regularly kill and eat adult seabirds, such as puffins and gulls and have been observed killing birds as large as a grey heron.[http://www.the-soc.org.uk/sb_index3.htm Scottish Ornithologists' Club] {{webarchive|url=https://web.archive.org/web/20110716221950/http://www.the-soc.org.uk/sb_index3.htm |date=2011-07-16 }} On the breeding grounds, the three, more slender northern breeding species commonly eat lemmings. Those species that breed in the southern oceans largely feed on fish that can be caught near their colonies. The eggs and chicks of other seabirds, primarily penguins, are an important food source for most skua species during the nesting season.{{cite book |last=Harrison |first=Colin J.O. |editor=Forshaw, Joseph |year=1991 |title=Encyclopaedia of Animals: Birds |publisher=Merehurst Press |location=London |pages=109 |isbn=1-85391-186-0}}

In the southern oceans and Antarctica region, some skua species (especially the south polar skua) will readily scavenge carcasses at breeding colonies of both penguins and pinnipeds. Skuas will also kill live penguin chicks and sick or injured adult penguins. In these areas, the skuas will often forfeit their catches to the considerably larger and very aggressive giant petrels. Skuas have also been observed to directly pilfer milk from the elephant seal's teats.{{cite journal |title=Antarctica's Milk-Stealing, Grudge-Holding Seabirds |journal=Boston NPR |date=2016 |url=http://archives.wbur.org/thewildlife/2016/03/29/antarcticas-milk-stealing-grudge-holding-seabirds/}}

Skuas are medium to large birds, typically with grey or brown plumage, often with white markings on the wings. The skuas range in size from the long-tailed skua, Stercorarius longicauda, at {{convert|310|g|lb|abbr=off}}, to the brown skua, Stercorarius antarcticus, at {{convert|1.63|kg|lb|abbr=on}}. On average, a skua is about {{convert|56|cm|in|abbr=on}} long, and {{convert|121|cm|in|abbr=on}} across the wings. They have longish bills with a hooked tip, and webbed feet with sharp claws. They look like large dark gulls, but have a fleshy cere above the upper mandible.

The skuas are strong, acrobatic fliers. They are generally aggressive in disposition. Potential predators approaching their nests will be quickly attacked by the parent birds, which usually target the heads of intruders – a practice known as 'divebombing'.{{cite news| url=https://www.bbc.co.uk/news/uk-scotland-highlands-islands-17338746| work=BBC News | title=Scottish Wildlife Trust builds £50,000 loo on Handa | date=12 March 2012}}

File:Stercorarius skua collage, Runde, Norway 06-06.jpg

File:Baby Skua.jpg still present on its beak]]

The genus Stercorarius was introduced by the French zoologist Mathurin Jacques Brisson in 1760 with the parasitic jaeger (Stercorarius parasiticus) as the type species.{{ cite book | last=Brisson | first=Mathurin Jacques | author-link=Mathurin Jacques Brisson | year=1760 | title=Ornithologie, ou, Méthode Contenant la Division des Oiseaux en Ordres, Sections, Genres, Especes & leurs Variétés | language=fr, la | at=[https://biodiversitylibrary.org/page/36010456 Vol. 1, p. 56], [https://biodiversitylibrary.org/page/36210999 Vol. 6, p. 149] | place=Paris | publisher=Jean-Baptiste Bauche }}{{ cite book | editor-last=Peters | editor-first=James Lee | editor-link=James L. Peters | year=1934 | title=Check-list of Birds of the World | volume=2 | publisher=Harvard University Press | place=Cambridge, Massachusetts | page=311 | url=https://biodiversitylibrary.org/page/14483124 }}

Skuas are related to gulls, waders, auks, and skimmers. In the three smaller species, all nesting exclusively in the Holarctic, breeding adults have the two central tail feathers obviously elongated, and at least some adults have white on the underparts and pale yellow on the neck. These characteristics are not shared by the larger species, all native to the Southern Hemisphere except for the great skua. Therefore, the skuas are often split into two genera, with only the smaller species retained in Stercorarius, and the large species placed in Catharacta. However, based on genetics, behavior, and feather lice, the overall relationship among the species is best expressed by placing all in a single genus.American Ornithologists' Union (2000). [http://www.aou.org/checklist/suppl/AOU_checklist_suppl_42.pdf Forty-second supplement to the American Ornithologists' Union Check-list of North American Birds.] The Auk 117(3):847–858. The pomarine and great skuas' mitochondrial DNA (inherited from the mother) is in fact more closely related to each other than it is to either Arctic or long-tailed skuas, or to the Southern Hemisphere species.Cohen, Baker, Belchschmidt, Dittmann, Furness, Gerwin, Helbig, de Korte, Marshall, Palma, Peter, Ramli, Siebold, Willcox, Wilson and Zink (1997). [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1688246/pdf/9061968.pdf Enigmatic phylogeny of skuas.] Proc. Biol. Sci. 264(1379):181–190. Thus, hybridization must have played a considerable role in the evolution of the diversity of Northern Hemisphere skuas.

The genus contains seven species:{{cite web| editor1-last=Gill | editor1-first=Frank | editor1-link=Frank Gill (ornithologist) | editor2-last=Donsker | editor2-first=David | year=2019 | title=Noddies, gulls, terns, auks | work=World Bird List Version 9.2 | url=https://www.worldbirdnames.org/bow/gulls/ | publisher=International Ornithologists' Union | access-date=24 June 2019 }}

{{Species table |genus=Skua |authority-name=Brisson|authority-year= 1760 |species-count=eight|no-note=y|narrow-percent=75}}

{{Species table/row

|name=Chilean skua|binomial=Stercorarius chilensis

|image=File:Catharacta chilensis (Chilean Skua).jpg|image-size=180px |image-alt=

|authority-name=Bonaparte|authority-year= 1857|authority-not-original=

|range= Breeds along the coasts of southern Chile and southern Argentina, winters along the Pacific coasts of Peru and Chile as well as the Atlantic coast of Argentina

|range-image=File:Stercorarius chilensis map.svg

|range-image-size=180px

|size=

|habitat=

|hunting=

|iucn-status= LC

|population=

|direction=

|subspecies=

}}

{{Species table/row

|name=South polar skua|binomial=Stercorarius maccormicki

|image=File:2007 Snow-Hill-Island Luyten-De-Hauwere, South Polar Skua 69.jpg|image-size=180px |image-alt=

|authority-name=Saunders|authority-year= 1893|authority-not-original=

|range=Breeds along the coast on Antarctica, winters in the north Atlantic and north Pacific

|range-image=File:Stercorarius maccormicki map.svg

|range-image-size=180px

|size=

|habitat=

|hunting=

|iucn-status= LC

|population=

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|subspecies=

}}

{{Species table/row

|name=Brown skua|binomial=Stercorarius antarcticus

|image=File:Stercorarius antarcticus -Godthul, South Georgia, British Overseas Territories, UK -landing-8.jpg|image-size=180px |image-alt=

|authority-name=Lesson|authority-year= 1831|authority-not-original=yes

|range= Southern Ocean

|range-image=File:Catharacta antarctica map.svg

|range-image-size=180px

|size=

|habitat=

|hunting=

|iucn-status= LC

|population=

|direction=

|subspecies={{Collapsible list |expand=yes |title=Three subspecies |bullets=on

|S. a. antarcticus (Lesson, 1831)

|S. a. hamiltoni (Hagen, 1952)

|S. a. lonnbergi (Mathews, 1912)

}}

}}

{{Species table/row

|name=Great skua|binomial=Stercorarius skua

|image=File:Stercorarius skua 1 (Martin Mecnarowski).jpg|image-size=180px |image-alt=

|authority-name=Brünnich|authority-year= 1764|authority-not-original=yes

|range= Breeds along the coastline of the northeast Atlantic, winters in the north Atlantic

|range-image=File:Stercorarius skua map.svg

|range-image-size=180px

|size=

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|iucn-status= LC

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{{Species table/row

|name=Pomarine jaeger or pomarine skua|binomial=Stercorarius pomarinus

|image=File:Stercorarius pomarinusPCCA20070623-3985B.jpg|image-size=180px |image-alt=

|authority-name=Temminck|authority-year= 1815|authority-not-original=yes

|range= Breeds along the Arctic coastline, winters in tropical and subtropical oceans

|range-image=File:StercorariusPomarinusIUCNver2018 2.png

|range-image-size=180px

|size=

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|iucn-status= LC

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{{Species table/row

|name=Parasitic jaeger or Arctic skua|binomial=Stercorarius parasiticus

|image=File:Parasitic Jaeger.jpg|image-size=180px |image-alt=

|authority-name=Linnaeus|authority-year= 1758|authority-not-original=yes

|range= Breeds along the Arctic coastline, winters in the southern hemisphere

|range-image=File:Stercorarius parasiticus map.svg

|range-image-size=180px

|size=

|habitat=

|hunting=

|iucn-status= LC

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{{Species table/row

|name=Long-tailed jaeger or long-tailed skua|binomial=Stercorarius longicaudus

|image=File:Long-tailed Skua, Svalbard 1.jpg|image-size=180px |image-alt=

|authority-name=Vieillot|authority-year= 1819|authority-not-original=

|range= Breeds in the Arctic, winters in the Southern Ocean

|range-image=File:Stercorarius longicaudus map.svg

|range-image-size=180px

|size=

|habitat=

|hunting=

|iucn-status= LC

|population=

|direction=

|subspecies={{Collapsible list |expand=yes |title=Two subspecies |bullets=on

| S. l. longicaudus Vieillot, 1819.

| S. l. pallescens Løppenthin, 1932

}}

}}

{{Species table/end}}

{{Reflist|group=note}}

{{Reflist}}

{{Wikispecies|Stercorariidae}}

{{Commons|Stercorariidae}}

• {{cite EB1911|wstitle=Skua |volume=25 |short=x}}
• [https://search.macaulaylibrary.org/catalog?taxonCode=gresku1&mediaType=video Great Skua videos] on the Internet Bird Collection

{{Charadriiformes|L.|state=collapsed}}

{{Taxonbar|from=Q205323}}

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Category:Seabirds

Category:Taxa named by Mathurin Jacques Brisson