|Central coordinates||68o 42.00' West 67o 52.00' South|
|Altitude||0 - 46m|
|Year of IBA assessment||2011|
Site description The Dion Islands are located in Maguerite Bay, ~14 km south of Adelaide Island on the western side of the Antarctic Peninsula. The small archipelago comprises several islands of less than 0.5 km across, with numerous islets, shoals of rocks, and reefs. The IBA is defined by the boundary of Antarctic Specially Protected Area No. 107: Emperor Island, Dion Islands, and is around 12 km from Ant003: Avian Island.
The Dion Islands have several patches of permanent ice though are generally ice-free in summer. The geology consists of fine-grained lavas and tuffs, with shales, sandstones, grits and conglomerates also present (ASPA No. 107 Management Plan, 2002). Soil development is minimal, consisting of small areas of ornithogenic mud and decayed moss and algae. Vegetation comprises cryptogams (including the mosses Syntrichia princeps, Polytrichastrum alpinum and Sanionia uncinata, BAS Plant Database, accessed 16/08/2010) and at least 19 species of lichen. There is likely to be a range of microinvertebrate fauna, fungi and bacteria, although these have not yet been studied.
All birds known to breed within the IBA have been recorded on Emperor Island, the second largest island in the Dion group. Emperor Island is rocky and precipitous and less than 0.5 km across at its widest point. A meltwater pond usually occurs on its northern side in summer.
The nearest permanent scientific stations are Teniente Luis Carvajal Station (Chile, summer-only with capacity for ~30 personnel), situated ~14 km to the northwest on the southern shore of Adelaide Island, and Rothera Station (UK, year-round with capacity for c. 100 personnel) located 41 km to the northeast and also on Adelaide Island.
No long-term meteorological records are available for the Dion Islands. However, at Teniente Luis Carvajal Station the mean daily maximum temperature was 3ºC in February for the period 1962-74, with the mean daily minimum temperature being –8ºC in August over the same period (ASPA No.107 Management Plan, 2002). This is similar to data recorded in 1949 by Stonehouse (1953, cited in ASPA No.107 Management Plan, 2002) at the Dion Islands. Winds prevail from a northerly direction, and most snowfall occurs between August and October, with light precipitation continuing through the austral summer.
Key Biodiversity The IBA is triggered by approximately 500 pairs of Imperial Shag (Phalacrocorax atriceps) recorded breeding on Emperor Island in the 1980’s (S. Poncet, pers. comm.). An Adélie Penguin (Pygoscelis adeliae) colony on Emperor Island was estimated at 700 pairs in 1987 (Woehler 1993).
Of particular note is the presence of a small Emperor Penguin (Aptenodytes forsteri) colony on a low-lying beach and rocky promontory in the southeast of Emperor Island. First discovered on the island in 1948 (Stonehouse, 1953 cited in ASPA No.107 Management Plan, 2002), this is the most northerly Emperor Penguin colony in Antarctica and one of only two sites where this species has been found breeding on land. Stonehouse (1953) recorded around 150 breeding pairs on the island in the winter of 1949 and numbers are thought to have fluctuated around this level until 1968, after which they may have increased. However, only 14 males with eggs were present on the island in winter of 1999 (ASPA No. 107 Management Plan, 2002), whilst a count made from 1998 and 2005 aerial imagery indicated less than 20 Emperor Penguins may remain breeding on the island (Fretwell & Trathan 2009). If these studies are typical of recent breeding patterns, the continued presence of Emperor Penguins on the island may be marginal.
Other confirmed breeders on Emperor Island include the Wilson’s Storm Petrel (Oceanites oceanicus), Kelp Gull (Larus dominicanus) and Brown Skua (Catharacta lonnbergi) nesting on the larger islands (data cited in ASPA No.107 Management Plan, 2002). However, these species have not been censused owing to the difficult access.
Non-bird biodiversity: Leopard Seals (Hydrurga leptonyx) are occasionally sighted in the Dion Islands, whilst Crabeater Seals (Lobodon carcinophagus) are commonly found on local ice floes. Weddell Seals (Leptonychotes weddellii) have also been recorded hauled out at Emperor Island (ASPA No.107 Management Plan, 2002).
|Species||Season||Period||Population estimate||Quality of estimate||IBA Criteria||IUCN Category|
|Phalacrocorax atriceps||breeding||1985||500 breeding pairs||-||A4i||Not Recognised|
Protection status ASPA No. 107
References ASPA No. 107 Emperor Island, Dion Islands: Management Plan (2002).
Poncet, S. 1982. Le Grand Hiver: Damien II Base Antarctique. Les Éditions Arthaud, Paris
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Recommended citation BirdLife International (2015) Important Bird Areas factsheet: Dion Islands. Downloaded from http://www.birdlife.org on 31/08/2015
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