Île aux Cochons is the westernmost island of the archipelago. It is a weakly eroded dome of volcanic origin, scattered with small, inactive craters. The coastline consists in part of low cliffs. Cats, rabbits and mice occur; there is, however, no human infrastructure and visits by scientific expeditions are rare.
See Box for key species. At least 19 species breed. Île aux Cochons is extremely important for its large penguin populations: it holds the world’s largest rookery of Aptenodytes patagonicus. The largest colony of Diomedea exulans in the Indian Ocean is also found here. Despite the presence of cats, large populations of small petrels still nest on the island, notably four million pairs of Pachyptila salvini salvini and one million pairs of Pelecanoides georgicus.
Non-bird biodiversity: Large populations of the mammals Mirounga leonina, Arctocephalus gazella and A. tropicalis breed, and two endemic plant species and 59 endemic arthropod species occur.
BirdLife International (2019) Important Bird Areas factsheet: Île aux Cochons. Downloaded from http://www.birdlife.org on 18/06/2019.