By virtue of their location in the Austral Ocean and their insularity, the sub-Antarctic islands form an exceptional environment. These islands are not part of the classic representation of mountains but have summits above 2,000 metres. Most of them do not have an extreme climate but rather borderline climatic conditions that prevented species from temperate regions, whose developmental thresholds are a few tenths of a degree above the usual sub-Antarctic temperatures, from establishing. Recent warming in these islands has opened the door to the colonisation of species that are potentially invasive or that at the very least can compete with sub-Antarctic species.
This article focuses on British South Georgia and French Kerguelen. The Kerguelen are located in the southern Indian Ocean, approximately 2,000 kilometres from the coast of Antarctica. South Georgia is located approximately 2,150 kilometres south of Tierra del Fuego.
