The mountainous island of South Georgia, situated in the cold but productive waters of the Southern Ocean, is one of the world’s most important seabird islands. It is estimated that over 100 million individual seabirds are based there, and that there may have been an order of magnitude more before the introduction of rats. South Georgia has 29 species of breeding bird, and is the world’s most important breeding site for six species (Macaroni Penguin Eudyptes chrysolophus, Grey-headed Albatross Thalassarche chrysostoma, Northern Giant Petrel Macronectes halli, Antarctic Prion Pachyptila desolata, White-chinned Petrel Procellaria aequinoctialis and Common Diving Petrel Pelecanoides urinatrix). It is also probably in the top three such sites for seven others (King Penguin Aptenodytes patagonicus, Gentoo Penguin Pygoscelis papua, Wandering Albatross Diomedea exulans, Black-browed Albatross Thalassarche melanophris, Southern Giant Petrel Macronectes giganteus, Black-bellied Storm-petrel Fregetta tropica and South Georgia Diving Petrel Pelecanoides georgicus). Several of these species are globally threatened or near-threatened, which enhances the importance of South Georgia and emphasises the need for action to improve the conservation status of its birds. Although South Georgia is currently classified by BirdLife International as a single Important Bird Area (IBA), closer scrutiny may well reveal that it would better be considered as comprising several distinct IBAs. Current threats to the South Georgia avifauna include rats, regional climate change, and incidental mortality in longline and trawl fisheries outside the Southern Ocean. The 2010/11 austral summer marked the start of a major campaign to eliminate rats. Local fisheries are now well regulated but South Georgia albatrosses and petrels are still killed in large numbers in more distant fisheries. Furthermore, there is probably little that can be done to mitigate the effects of climate change.