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LC
Imperial Shag Phalacrocorax atriceps

Justification
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 is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not 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.

Taxonomic source(s)
SACC. 2006. A classification of the bird species of South America. Available at: http://www.museum.lsu.edu/~Remsen/SACCBaseline.html.
Turbott, E. G. 1990. Checklist of the birds of New Zealand. Ornithological Society of New Zealand, Wellington.

Taxonomic note
Phalacrocorax atriceps (Turbott 1990) includes bransfieldensis, verrucosus and georgianus contra Sibley and Monroe (1990, 1993). Seven species have been recognised involving the southern cormorant complex including four by Siegel-Causey (1988) (followed by Sibley and Monroe 1990, 1993) and six by Marchant and Higgins (1990). Siegel-Causey's findings were tentative and not based on DNA study (J. Cooper in litt. 1998). Given this uncertainty and the possibility of various treatments, BirdLife has not split P. atriceps thus far, although it is clear that any change in taxonomy would result in the recognition of additional threatened species.

Synonym(s)
Leucocarbo atriceps Turbott (1990), Leucocarbo atriceps atriceps Christidis and Boles (2008), Leucocarbo atriceps atriceps Turbott (1990)

Distribution and population
Four discrete ranges exist. Phalacrocorax atriceps is found on the southern tip of South America, from central Chile round to central Argentina, and on the Falkland Islands (Islas Malvinas). Phalacrocorax (atriceps) bransfieldensis breeds on the Antarctic Peninsula and the South Shetland Islands. Phalacrocorax (atriceps) georgianus is found on the islands of South Georgia (Georgia del Sur), the South Orkney Islands, South Sandwich Islands (Islas Sandwich del Sur) and Shag Rocks (Scotia Sea). In the Indian Ocean, Phalacrocorax (atriceps) verrucosus is restricted to the Kerguelen Islands (French Southern Territories), Phalacrocorax (atriceps) melanogenis occupies the Crozet Islands (French Southern Territories), Phalacrocorax (atriceps) nivalis is found on Heard Island (to Australia) and Phalacrocorax (atriceps) purpurascens is restricted to Macquarie Island (to Australia) (del Hoyo et al. 1992).

Trend justification
The overall population trend is uncertain, as some populations are decreasing, while others are fluctuating, stable, or have unknown trends (Wetlands International 2006).

Ecology
This marine species forages in subantartic and Antarctic waters along the coast and around islands. It feeds in inshore waters having a diet which varies geographically, but including fish, crustaceans, squid and benthic invertebrates including sea urchins in the Kerguelen Islands. Breeding begins in either October or November, forming colonies up to hundreds of thousands of birds which are very dense (del Hoyo et al. 1992).

Related state of the world's birds case studies

References
del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.

Text account compilers
Calvert, R., Taylor, J., Shutes, S.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Phalacrocorax atriceps. Downloaded from http://www.birdlife.org on 24/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/04/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Imperial shag (Phalacrocorax atriceps) 0

Key facts
Current IUCN Red List category Least Concern
Family Phalacrocoracidae (Cormorants)
Species name author King, 1828
Population size 340000-1400000 mature individuals
Population trend Unknown
Distribution size (breeding/resident) 365,000 km2
Country endemic? No
Links to further information
- Additional Information on this species