to provide a fresh food source to sailors who might become shipwrecked. Rabbits have devastated the islands' plant communities, and have caused serious erosion in places where their numbers have exploded – mostly the eastern half of the islands, where population densities have reached 40+ per acre in some places. To date, the western and northwestern limits of the islands have been spared due to a less hospitable climate. The off-lying islands surrounding the archipelago have also been spared. Rats. Cats. The islands are home to a population of feral cats descended from ships' cats kept by sailors to control the rat population. The cats live mainly on rabbits and seabirds. Birds Penguins: King penguin (Aptenodytes patagonicus) Gentoo penguin (Pygoscelis papua) Southern rockhopper penguin (Eudyptes chrysocome) Macaroni penguin (Eudyptes chrysolophus) Seabirds: Albatross Sheathbills Cormorants Petrels Seagulls Prions Skuas Terns The Kerguelen Islands are covered by France's ratification of the international Agreement on the Conservation of Albatrosses and Petrels, drawn up under the auspices of the Convention on Migratory Species. Anseriformes: Eaton's pintail (Anas eatoni) Mallard (Anas platyrhynchos) introduced Fish In the 1950s and 1960s, Edgar Albert de la Rue, a French geologist began the introduction of several species of salmonids. Of the seven species introduced, only brook trout and brown trout survived to establish wild populations. Brook trout occupy head water streams, while brown trout have established both resident stream and robust anadromous populations throughout the islands. Flora Land vegetation The coastal regions, up to an altitude of about 50 m, are generally covered with low herbaceous vegetation, and are classified as tundra. Higher up, rocky ground dominates and the vegetation is rarer, limited to scattered tufts and mosses and lichens. There are no trees or shrubs on the islands. This was not always the case, however. Fossilized tree trunks of the family Araucariaceae can be found in certain sediments, geological witnesses of times when Kerguelen had a warmer climate than today. Originally, the main type of low altitude vegetation consisted of a thick and continuous carpet of azorellae (Azorella selago) on which could be established various other species such as the famous Kerguelen cabbage, Pringlea antiscorbutica (family Brassicaceae). The azorella (Apiaceae) had a pillow-shaped growth: the year's growth forming a tight layer which superimposed itself on the previous year's growth. The species Lyallia kerguelensis (Hectorellaceae), the only strictly endemic species of the archipelago, has a similar growth pattern. The