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Site description (2015 baseline)

Southern Powell Island is located 7 km east of the southwestern extremity of Coronation Island, between Lewthwaite Strait and Washington Strait, South Orkney Islands. Much of the land area at this site is ice-free in summer, although a permanent icecap covers much of Powell Island. The IBA qualifies on the basis of the Chinstrap Penguin (Pygoscelis antarctica), Gentoo Penguin (P. papua), Adélie Penguin (P. adeliae), Imperial Shag (Phalacrocorax [atriceps] bransfieldensis), and Southern Giant Petrel (Macronectes giganteus) colonies present. The IBA boundary follows the boundary of ASPA No. 111.

Vegetation at the site includes moss banks at southern Powell Island, Christoffersen Island and northern Fredriksen Island, and extensive cover of the alga Prasiola crispa associated with breeding penguins (ASPA No. 111 Management Plan, 2012). Snow algae also grow on glaciated areas and snow patches around the site.

The nearest research station is Orcadas (ARG), which lies ~17 km to the southeast on Laurie Island and operates year-round with accommodation for ~45 people in summer and a winter complement of ~14 people (COMNAP, Antarctic Facilities, accessed 01/09/2010). See IBA Signy Island for information on meteorological records and facilities at Signy Station (GBR), located 35 km to the west.

Key biodiversity

Southern Powell Island is one of the most populous sites for breeding birds in the South Orkney Islands. Over 2900 breeding pairs of Gentoo Penguin were recorded in 1983, at several sites on southern Powell Island (1729 pairs), Michelsen Island (870 pairs) and Christoffersen Island (324 pairs) (Poncet & Poncet 1985). In the same year, 16 750 pairs of Adélie Penguin and 28 100 pairs of Chinstrap Penguin were recorded at the site. Adélie Penguins breed on Michelsen Island (9000 pairs) and on southern Powell Island (7500 pairs), with a smaller colony on Christoffersen Island (250 pairs). The most abundant Chinstrap breeding site is on Fredriksen Island (21 320 pairs), while smaller colonies are located on southern Powell Island, the southern coast of Michelsen Island (4435 pairs) and on Grey Island (2350 pairs) (Poncet & Poncet 1985). A few Macaroni Penguins ( Eudyptes chrysolophus ) also breed among the Gentoo Penguins at the site (ASPA No. 111 Management Plan, 2012).

Southern Giant Petrel breed on southern Powell Island and on Christoffersen and Michelsen islands, with 613 breeding pairs on Powell Island in 1982/83 and 83 pairs on Michelsen Island in 1957 (Patterson et al . 2008). Other breeding birds include the Imperial Shag (144 breeding pairs nesting among Chinstrap Penguins on the northern coast of Grey Island in 1988), and Snow Petrel ( Pagodroma nivea ), which breeds at Ellefsen Harbour, Michelsen Island and Fredricksen Island (Croxall et al . 1995). Kelp Gull ( Larus dominicanus ), Cape Petrel ( Daption capense ), Brown Skua ( Catharacta antarctica ) and Snowy Sheathbill ( Chionis albus ) also breed at the site, and Antarctic Prion ( Pachyptila desolata ) and Black-bellied Storm-petrel ( Fregetta tropica ) are possible breeders (ASPA No. 111 Management Plan, 2012).

Non-bird biodiversity: Antarctic Fur Seal (Arctocephalus gazella) breed on Michelsen Island, with an upward trend in the breeding population since the 1950s (ASPA No. 111 Management Plan, 2012). Non-breeding mammals observed at the site include Southern Elephant Seal (Mirounga leonina), Weddell Seal (Leptonychotes weddellii) and occasionally Leopard Seal (Hydrurga leptonyx) and Crabeater Seal (Lobodon carcinophagus).

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Southern Powell Island and adjacent islands (Antarctica). Downloaded from https://datazone.birdlife.org/site/factsheet/southern-powell-island-and-adjacent-islands-iba-antarctica on 22/11/2024.