Brown Skua Catharacta antarctica


Taxonomic note
Catharacta antarctica (del Hoyo and Collar 2014) was previously placed in the genus Stercorarius, following Chu et al. (2009), and split as S. antarcticus and S. lonnbergi, following Sibley and Monroe (1990, 1993).

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - -

Red List history
Year Category Criteria
2018 Least Concern
2016 Least Concern
2014 Least Concern
Species attributes

Migratory status full migrant Forest dependency Does not normally occur in forest
Land mass type Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 135,000,000
Extent of Occurrence non-breeding (km2) 86,100,000
Number of locations -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 26000-28000 poor estimated 1996
Population trend Decreasing suspected -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) - - -
Decline (10 years/3 generation past and future) - - -
Number of subpopulations - - -
Largest subpopulations - - -
Generation length (yrs) 17.1 - - -

Population justification: The total population has been estimated to number c.13,000-14,000 pairs (del Hoyo et al. 1996), assumed to equate to 26,000-28,000 mature individuals, or 39,000-42,000 individuals in total.

Trend justification: The largest known colony of the nominate race, C. antarctica antarctica, has undergone a 47% decline in the last 5 years, as such the species is suspected to be in decline, but the overall magnitude of decline is uncertain.

Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Angola U Extant
Antarctica N Extant Yes Yes
Argentina N Extant
Australia N Extant Yes Yes
Bouvet Island (to Norway) N Extant Yes
Brazil U Extant
Chile U Extant
Falkland Islands (Malvinas) N Extant
French Southern Territories N Extant Yes
Heard Island and McDonald Islands (to Australia) N Extant Yes
India V Extant
Iran, Islamic Republic of V Extant
Maldives N Extant
New Zealand N Extant Yes Yes
Norfolk Island (to Australia) N Extant
Oman V Extant Yes
Seychelles N Extant
South Africa N Extant Yes
South Georgia & the South Sandwich Islands N Extant Yes Yes
Sri Lanka N Extant
St Helena (to UK) U Extant Yes
Uruguay N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Antarctica Signy Island

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Grassland Subantarctic major breeding
Marine Coastal/Supratidal Sea Cliffs and Rocky Offshore Islands major breeding
Marine Intertidal Rocky Shoreline suitable breeding
Marine Intertidal Shingle and/or Pebble Shoreline and/or Beaches suitable breeding
Marine Intertidal Tidepools suitable breeding
Marine Neritic Macroalgal/Kelp suitable non-breeding
Marine Neritic Macroalgal/Kelp suitable breeding
Marine Neritic Pelagic major non-breeding
Marine Neritic Pelagic major breeding
Marine Neritic Seagrass (Submerged) suitable non-breeding
Marine Neritic Seagrass (Submerged) suitable breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel suitable non-breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel suitable breeding
Marine Neritic Subtidal Rock and Rocky Reefs suitable breeding
Marine Neritic Subtidal Rock and Rocky Reefs suitable non-breeding
Marine Neritic Subtidal Sandy suitable non-breeding
Marine Neritic Subtidal Sandy suitable breeding
Marine Neritic Subtidal Sandy-Mud suitable non-breeding
Marine Neritic Subtidal Sandy-Mud suitable breeding
Marine Oceanic Epipelagic (0-200m) suitable non-breeding
Marine Oceanic Mesopelagic (200-1000m) suitable non-breeding
Altitude   Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Invasive and other problematic species, genes & diseases Problematic native species/diseases - Phalcoboenus australis Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines Low Impact: 5
Competition, Reduced reproductive success

Recommended citation
BirdLife International (2019) Species factsheet: Catharacta antarctica. Downloaded from on 13/12/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from on 13/12/2019.