Catharacta skua 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Stercorariidae

Scientific Name: Catharacta skua (Brünnich, 1764)
Regional Assessments:
Common Name(s):
English Great Skua
French Grand Labbe
Stercorarius skua Brünnich, 1764
Stercorarius skua ssp. skua — AOU checklist (1998 + supplements)
Stercorarius skua ssp. skua — Cramp and Simmons (1977-1994)
Taxonomic Source(s): Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Taxonomic Notes: Catharacta skua (del Hoyo and Collar 2014) was previously placed in the genus Stercorarius.

Catharacta skua,
C. antarctica and C. maccormicki (Sibley and Monroe 1990, 1993), cross-regional species, are retained as separate species contra Christidis and Boles (1994) and Turbott (1990) who include lonnbergi and antarctica as subspecies of C. skua and AERC TAC (2003) who include C. maccormicki as a subspecies of C. skua.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2017
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Ashpole, J, Butchart, S., Calvert, R., Ekstrom, J.
Although this species may have a small range, it is not believed to approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species breeds in Iceland, Norway, Svalbard (to Norway), the Faroe Islands (to Denmark), the Scottish islands and a few on mainland Scotland. It is a migratory species, normally wintering off the Atlantic coast of France and the Iberian Peninsulas, but juveniles can reach as far as Cape Verde, the coast of Brazil, areas of the Caribbean and small numbers also winter on the Grand Banks of Newfoundland (Canada) (del Hoyo et al. 1996).
Countries occurrence:
Algeria; Antigua and Barbuda; Austria; Barbados; Belgium; Belize; Brazil; Bulgaria; Canada; Cape Verde; Colombia; Denmark; Dominica; Egypt; Faroe Islands; France; French Guiana; Germany; Gibraltar; Greenland; Guyana; Iceland; Ireland; Italy; Libya; Martinique; Mauritania; Montserrat; Morocco; Netherlands; Norway; Panama; Portugal; Puerto Rico; Russian Federation (Central Asian Russia - Vagrant, European Russia); Saint Kitts and Nevis; Saint Lucia; Saint Pierre and Miquelon; Saint Vincent and the Grenadines; Slovakia; Spain; Suriname; Svalbard and Jan Mayen; Sweden; Tunisia; United Kingdom; United States
Bermuda; Côte d'Ivoire; Croatia; Cuba; Czech Republic; Finland; Ghana; Greece; Guadeloupe; Hungary; Israel; Latvia; Liberia; Lithuania; Luxembourg; Malta; Montenegro; Nigeria; Poland; Romania; Senegal; Serbia; Slovenia; Switzerland; Turkey
Present - origin uncertain:
Anguilla; Cyprus; Gambia; Guinea; Guinea-Bissau; Lebanon; Sierra Leone; Syrian Arab Republic; Trinidad and Tobago; Venezuela, Bolivarian Republic of; Virgin Islands, British; Virgin Islands, U.S.; Western Sahara
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:4300000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The breeding population, which is confined to Europe, is estimated at 16,300-17,200 pairs, which equates to 32,600-34,500 mature individuals (BirdLife International 2015).

Trend Justification:  The population is suspected to be stable in the absence of evidence for any declines or substantial threats. The European population trend is unknown (BirdLife International 2015).
Current Population Trend:Stable
Additional data:
Number of mature individuals:30000-34999Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:This marine species avoids land during migration and winter, aggregating in winter in areas where it can scavenge from fisheries. It has a hugely varied diet owing to be being a highly opportunistic feeder. Individuals regularly show individual specialisations in diet and feeding with some colony-specific learning. Breeding begins in May, and it is loosely colonial but highly territorial, breeding on islands on flat ground with some vegetation cover, usually avoiding human contact. Most birds breed within 1 km of their birth place (del Hoyo et al. 1996).
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):17.5
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): The following information refers to the species's European range only: Declines in Shetland have been due to a recent reduction in sand eel stocks that have resulted in reduced breeding success and less birds at the largest colonies. Changes in fishing practices could also have serious impacts as more than half the summer diet at Shetland is made up of discards from fisheries (Furness 1996) and when discard rates are reduced this species will switch to predating other birds, especially if small shoaling pelagic fish are scarce (Votier et al. 2004). Fishing activities also pose a threat through drowning in fishing nets or being caught on hooks. Human persecution (often illegal) has limited the size of some colonies although harvesting for food has now nearly ceased (Furness 1996). The species is also affected by climate change (Oswald et al. 2008).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
The following information refers to the species's European range only: There are currently no known significant conservation measures for this species.

Conservation Actions Proposed
The following information refers to the species's European range only: As it is not desirable to maintain current rates of fish discard, conservation measures are needed to conserve sandeel stocks in order to provide an alternative food source for this species and avoid a switch to preying on other bird species, which may impact populations of other seabirds (Votier et al. 2004).

Amended [top]

Amended reason: Map revised.

Citation: BirdLife International. 2017. Catharacta skua (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22694160A110633436. . Downloaded on 19 April 2018.
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