Justification of Red List Category
This species has a very large range, and hence does not 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.
The population is placed in the band 10,000-19,999 individuals, equating to 6,667-13,333 mature individuals, rounded here to 6,000-15,000 mature individuals.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
The South Polar Skua breeds throughout the Antarctic coast, especially in the Ross Sea area. It undergoes a transequatorial migration, wintering as far north as Alaska (USA) and Greenland (to Denmark).
The South Polar Skua breeds on relatively snow-free areas in Antartica (del Hoyo et al. 1992). It is usually reliant on fish (Pietz 1987), with predation on penguins being of variable importance (del Hoyo et al. 1992). It can, however, subside exclusively on penguins where a breeding colony is associated to a penguin rookery (Trillmich 1978, Young and Miller 1999). It is a trans-equatorial migrant, wintering in the North Pacific and North Atlantic (del Hoyo et al. 1992).
At present there are no factors thought to pose a genuine threat to this species.
Text account compilers
Ekstrom, J., Bennett, S., Calvert, R., Butchart, S., Martin, R., Stuart, A.
BirdLife International (2019) Species factsheet: Catharacta maccormicki. Downloaded from http://www.birdlife.org on 22/04/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/04/2019.