This site covers a small group of islands and islets to the east of the northern tip of Grande Terre. The largest island, Île de Castries, is about 500 ha. The landscape of the islands is mostly flat, rising westwards to meet coastal cliffs. Access from the sea is virtually impossible because of the extensive banks of the seaweed Macrocystis pyrifera which surround the islands. It is likely therefore that humans have never set foot on these islands.
See Box for key species. The only data available are from observations made offshore and so are inevitably incomplete. Five or six pairs of Diomedea exulans breed (1989 data) as do unknown numbers of Macronectes halli. It is possible that the site is of importance for several petrel species, while numbers of breeding Phalacrocorax verrucosus exceed the threshold, but quantitative data are lacking.
Non-bird biodiversity: The flora is thought to be pristine. A large colony of the fur seal Arctocephalus gazella occurs. This population has probably never been exploited, which has enabled the recolonization of other sites from where the species had been exterminated.
BirdLife International (2021) Important Bird Areas factsheet: Îles Leygues. Downloaded from http://www.birdlife.org on 25/01/2021.