Sites - Important Bird Areas (IBAs)

Ornithological information Seven bird species are known to breed on the island, more than at most other sites in the region. An Adélie Penguin (Pygoscelis adeliae) colony occupies much of the northern half of the island with 35,600 breeding pairs estimated in 1979, representing one of the largest breeding colonies on the Antarctic Peninsula. A large Imperial Shag (Phalacrocorax atriceps) colony has been recorded on the southwestern coast of the island, totalling 670 pairs in 1989 (Poncet & Poncet, unpublished data). Avian Island holds the largest breeding colony of Southern Giant Petrel (Macronectes giganteusi) south of the South Shetland Islands, with 250 breeding pairs recorded in 1990 (Poncet & Poncet 1990) and 237 chicks estimated in 2001 (Harris 2001). A colony of Kelp Gulls (Larus dominicanus) of around 60 pairs breed near the southern extent of their range on Avian island (Poncet & Poncet 1979), and South Polar Skua (Catharacta maccormicki) breeding colonies are present in central and eastern parts of the island (Fraser pers. comm. in Ritz et al. 2005). The southernmost record of breeding Brown Skua (Catharacta lonnbergi) has also been documented on Avian Island and several hundred pairs of Wilson’s Storm Petrel (Oceanites oceanicus) breed in rocky outcrops around the island (Poncet & Poncet 1979).

Non-breeding species observed on Avian Island include the Antarctic Tern (Sterna vittata), Southern Fulmar (Fulmarus glacioloides), Antarctic Petrel (Thalassoica antarctica), Cape Petrel (Daption capense), King (Aptenodytes patagonicus) and Chinstrap (Pygoscelis antarctica) penguins.

Site description Avian Island is a small island lying ~0.5 km south of Adelaide Island in Marguerite Bay, on the western side of the Antarctic Peninsula. Avian Island is one of the most ornithologically important sites in the Antarctic Peninsula region, and is designated as Antarctic Specially Protected Area (ASPA) No. 117. The ASPA includes the littoral zone, offshore islets and rocks and a 100 m buffer zone around the shoreline. The IBA is defined by the boundary of the ASPA.

Avian Island is of rocky, low relief of up to 40 m, with an irregular coastline. The southern coastline features steep cliffs with rocky ledges, suitable for small nesting birds. Other bird habitats include scattered rocks and boulders, ice-free ground, and a gently sloping, well-drained northern shoreline. Several ephemeral freshwater ponds, meltwater channels and small streams are present. Strong tidal currents are common in the surrounding sea, helping to keep coastal waters ice-free. In addition, strong winds reduce snow accumulation, resulting in more favourable conditions for bird colonisation (ASPA No. 117 Management Plan, 2002). Vegetation is sparse across Avian Island and dominated by lichens and mosses.

The nearest permanent scientific station is Teniente Luis Carvajal (Chile), a summer-only station lying ~1 km from Avian Island on the southern shore of Adelaide Island. No long-term meteorological records are available for Avian Island. However, at Teniente Luis Carvajal Station the mean daily maximum temperature was 3ºC in February for the period 1962-74, whilst the mean daily minimum temperature was –8ºC in August for the same period (ASPA No. 117 Management Plan, 2002). Most snowfall occurs between August and October, with light precipitation occurring through the austral summer.

Populations of IBA trigger species

Other biodiversity Weddell Seals (Leptonychotes weddellii) and Elephant Seals (Mirounga leonina) commonly haul out and breed on Avian Island (ASPA No. 117 Management Plan, 2002). Non-breeding Antarctic Fur Seals (Arctocephalus gazella) also frequent the island with several hundred present on low-lying ground and beaches in February 2001 (Harris 2001). Leopard Seals (Hydrurga leptonyx) are also occasionally observed on Avian Island.

Protection status ASPA No.117

Conservation response The principal reason for designation of Avian Island as a protected area in 1989 was to protect the unusually large and diverse colonies of breeding birds. The Management Plan for ASPA No. 107 is designed to allow scientific research in the area but ensure visitor impacts are low. Entry to the ASPA is allowed only by permit and aircraft overflight is restricted year-round. The boundaries of the protected area were designed to include the surrounding marine as a buffer to help protect nesting birds. Visits to the island are infrequent, and disturbance to breeding birds by visitors remains low.

The past impact of visitors to Avian Island are believed to have been minor although these have not been well documented (ASPA No.117 Management Plan, 2002).The Management Plan notes that a few human visits have caused loss of eggs and chicks through nest abandonment or predation. Two refuges and beacon structures are in poor repair on the island, with rusting cans, roofing iron, wood and glass exposed to locally breeding birds, some of which were observed amongst debris in February 2001. A large beacon was installed in 1998 in the Southern Giant Petrel breeding area, and the level of disturbance to breeding birds during installation and maintenance are unknown. Southern Giant Petrels and Kelp Gulls are particularly vulnerable to disturbance.

The island is close to a permanent summer research station, where activities have included the use of small boats and aircraft. A snow runway once existed on southern Adelaide Island, the access route to which crossed the general area of Avian Island, although the status and use of this runway is currently unknown.

References ASPA No. 117 Avian Island: 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 (2013) Important Bird Areas factsheet: Avian Island. Downloaded from http://www.birdlife.org on 19/06/2013

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