The brown skua (Catharacta antarctica) belongs to the family of skuas and jaegers, Stercorariidae.
These skua species are distributed in Antarctic Peninsula, subantarctic regions of the Atlantic, Indian and Pacific Oceans. Vagrant brown skua populations have been observed in the coasts of India, Oman and Iran. There are three recognized subspecies of brown skua.
Brown skua - Overview
- Scientific name: Catharacta antarctica
- Species author: (Lesson, 1831)
- Synonyms/Protonym: Lestris antarcticus Lesson, 1831, Stercorarius antarcticus
- Family: Stercorariidae › Charadriiformes › Aves › Chordata › Animalia
- Vernacular names: English: Brown skua, Chinese: 棕贼鸥, French: Labbe antarctique, German: Subantarktikskua, Spanish: Págalo subantártico, Russian: Антарктический поморник, Japanese: ミナミオオトウゾクカモメ
- Other names: Antarctic skua, subantarctic skua, southern great skua
- Distribution: Antarctic Peninsula, subantarctic regions of the Atlantic, Indian and Pacific Oceans
- Diet and feeding habits: fish, birds, small mammals, carrion
- IUCN status listing: Least Concern (LC)
The three recognized subspecies of brown skua are: Catharacta antarctica antarctica (Lesson, 1831), Catharacta antarctica hamiltoni Hagen, 1952 and Catharacta antarctica lonnbergi Mathews, 1912.
Appearance, physical description and identificationThe brown skua (Catharacta antarctica) is a large seabird, measuring about 65 cm in length and weighing 1500 to 2200 grams. The wingspan is 125 to 160 cms.
The overall plumage of these species is brownish shades with pale flecking. Both the sexes look alike, but the female is larger. The wings are long, broad and pointed. The wings have distinctive white outer wing flashes.
The bill of the skua is black and hooked. The legs are dark gray with webbed feet and sharp claws. The irises are black. Their call is a repetitive “couk...couk...couk" sound.
|Birds of India - Image of Brown skua - Catharacta antarctica|
|Indian birds - Picture of Brown skua - Catharacta antarctica|
|Birds of India - Photo of Brown skua - Catharacta antarctica by Liam Quinn|
Origin, geographical range and distributionThe brown skua species are distributed in the coasts of Antarctica, Australia, Heard Island and McDonald Islands, French Southern Territories, New Zealand, Norfolk Island, St Helena, Uruguay, Falkland Islands, Argentina, South Africa, Sri Lanka, Maldives and Seychelles.
The subspecies C. a. antarctica is distributed Falkland Islands and South Argentina and winters in South America. The subspecies C. a. hamiltoni is distributed Tristan da Cunha and Gough Islands and is sedentary.
The subspecies C. a. lonnbergi is distributed Antarctic Peninsula and subantarctic regions of Atlantic, Indian and Pacific Oceans. Vagrant brown skua populations have been observed in the coasts of India, Oman and Iran.
Ecosystem and habitatThe brown skua species do not normally occur in forests. These species occur in altitudes from 0 to 100 meters. They inhabit subantarctic grasslands and various marine ecosystems.
The brown skuas inhabit marine ecosystems like, rocky offshore islands, intertidal rocky shoreline, intertidal beaches, intertidal pools, shallow seas with macroalgal growth (kelp and seagrass), marine pelagic zones and oceanic zones.
Diet and feeding behaviorThe diet of these brown skua species is mostly fish and birds. Fish, birds, small mammals and carrion are the primary food. They feed opportunistically on prey. They are found to scavenge around fishing boats and ships.
They prey upon eggs and chicks of penguins, adults and fledgling petrels, burrow-nesting prions, gadfly petrels, storm-petrels and shearwaters. They are also kleptoparasites, robbing the seabirds of their catch by high speed pursuit and strikes from above.
Reproduction and breeding habitsThe breeding season of these brown skua species is from September to December. Loose breeding colonies are formed. These birds are monogamous and highly territorial and attack intruders. Quite often breeding territories are occupied by trios, comprising one female and two males.
These skua species nest on grass, gravel or bare rock. Sometimes the scrape nest may be lined with grass or moss. The typical clutch contains two large pale brown mottled eggs. Both the parents take part in incubation and in feeding chicks. The chicks hatch out in 29 to 33 days and fledge at 58 to 63 days.
Migration and movement patternsThe brown skua is a partially migratory bird.
Breeding populations of brown skua occur in Antarctic Peninsula and subantarctic regions of the Atlantic, Indian and Pacific Oceans. They disperse slightly northwards from the breeding grounds for wintering.
Post breeding, the brown skua juveniles may disperse and establish in new locations within the range. They may make local movements for feeding and breeding within their range.
Conservation and survivalThe global population size of the brown skua (Catharacta antarctica) is estimated to be around 39,000 to 42,000 individual birds. The overall population trend of these species is considered to be stable. Throughout its range it is reported to be rare to common. The generation length is 17.1 years. Their distribution size is about 135,000,000 sq.km.
The brown skua (Catharacta antarctica) does not approach the thresholds for being Vulnerable either under the range size criterion, or the population trend criterion or under the population size criterion. Loss of habitat due to global warming is the main threat that may endanger the survival of these species.
IUCN and CITES statusThe IUCN (International Union for Conservation of Nature) has categorized and evaluated the skua species and has listed it as of "Least Concern". CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) status is ‘Not Evaluated’ for the brown skua (Catharacta antarctica).
1.Image source: https://commons.wikimedia.org/wiki/File:Brownskua_inggeorgeisland.jpg
Image author: Henrike Mühlichen | License: CC BY-SA 3.0
2.Image source: https://commons.wikimedia.org/wiki/File:Skua_Terra_Nova_Bay_02.jpg
Image author: Francisco Ardini/PNRA | License: CC BY-SA 4.0
3.Image source: https://en.wikipedia.org/wiki/File:Stercorarius_antarcticus_-Godthul,_South_Georgia,_British_Overseas_Territories,_UK_-landing-8.jpg
Image author: Liam Quinn | License: CC BY-SA 2.0 (as on 21/02/17)
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