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Location Antarctica
Central coordinates 63o 57.97' West  64o 47.62' South
IBA criteria A4i
Area 22 ha
Altitude 0 - 32m
Year of IBA assessment 2015

Site description Cormorant Island is a small (10 ha), ice-free island located in Bismarck Strait, ~1 km south of Anvers Island and ~5 km from Arthur Harbour and Palmer Station (US). The island is named for the large numbers of Imperial Shag (Phalacrocorax atriceps) observed on the island during British surveys carried out in 1955-57 (Hattersley-Smith, 1991).

Cormorant Island and the nearshore marine area up to 50 m surrounding the island is now designated a Restricted Zone under the Management Plan for Antarctic Specially Managed Area No. 7: Southwest Anvers Island and Palmer Basin. The IBA covers the area defined by the boundary of the Restricted Zone.

Anvers Island and surrounding islands are dominated by granitic and volcanic rocks. Vegetation comprises a wide range of mosses, lichens and algae and includes the two native Antarctic vascular species, Deschampsia Antarctica and Colobanthus quitensis (ASMA No.7 Management Plan, 2009).

The nearest permanent scientific station to the IBA is Palmer (US), situated ~5 km to the northwest in Arthur Harbour. Palmer Station operates year-round, with a summer occupancy of ~43 people (COMNAP, Antarctic Facilities, accessed 16/08/2010).

Climate data are not available specifically for Cormorant Island, although good records exist for nearby Palmer Station, where the average annual air temperature for the period 1989-2009 was –1.7°C. The minimum and maximum temperatures recorded at Palmer Station over the same period were –26.0°C and 11.6°C respectively. January is typically the warmest month and August the coldest (CLIMDB/HYDRODB, accessed 16/08/2010). Average annual precipitation has been 655 mm since 1989. Storms in the region are relatively frequent, whilst prevailing winds are generally light to moderate and from the northeast (ASMA No.7 Management Plan, 2009).

Key Biodiversity Cormorant Island is one of the largest colonies of Imperial Shag (Phalacrocorax atriceps) in the Antarctic Peninsula region, with 729 breeding pairs recorded in 1985 (Poncet & Poncet, unpublished data). Adélie Penguins (Pygoscelis adeliae) also breed on Cormorant Island, with 872 pairs recorded in the last published count (Parmelee & Parmelee, 1987). Southern Giant Petrels (Macronectes giganteusi) breed on the island, numbering around 13 breeding pairs (W. Fraser, pers. comm., 2006).

Non-bird biodiversity: Fin Whale (Balaenoptera physalus) and Sei Whale (Balaenoptera borealis) have previously been observed near southern Anvers Island (ASMA No.7 Management Plan, 2009). Other species observed in the area include the Minke Whale (Balaenoptera bonaerensis), Killer Whale (Orcinus orca), Humpback Whale (Megaptera novaeangliae), Southern Right Whale (Eubalaena australis) and Hourglass Dolphin (Lagenorhynchus cruciger).

Seal species common to the Anvers Island area include the Weddell Seal (Leptonychotes weddellii), Southern Elephant Seal (Mirounga leonina), Crabeater Seal (Lobodon carcinophagus), Leopard Seal (Hydrurga leptonyx) and Antarctic Fur Seal (Arctocephalus gazella). However, there are no records of seals breeding in the area (ASMA No. 7 Management Plan, 2009).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Imperial Shag Phalacrocorax atriceps breeding  1985  729 breeding pairs  good  A4i  Least Concern 

Protection status Restricted Zone within ASMA No.7

References ASMA No. 7 Palmer Basin and Southwest Anvers Island: Management Plan (2008), Appendix A.

See also: Palmer LTER project site at

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Cormorant Island. Downloaded from on 27/10/2016

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