This site covers the western half of Péninsule Rallier du Baty in south-western Grande Terre. It is bordered to the north by the Cook Glacier and, to the east and south, by the main mountain ridge of the peninsula and the Arête Jérémine, respectively. Protected by rivers and glaciers, it is the only part of Grande Terre free from rats and cats, while rabbits are restricted to the northern part of the site. The landscape is mostly devoid of vegetation and the relief is very hilly, with glaciers covering mountain peaks. The mountains are interrupted by large, westward-sloping, glaciated valleys. The area is geothermically active, indicated by vents of steam and gas. Human visits to the site are only very occasional.
See Box for key species. This site holds very high densities of seabirds and at least 31 species breed. Penguins are particularly common as, in addition to those listed below, 10,000 pairs of E. chrysocome breed. The colony of Diomedea exulans is the largest in Kerguelen. It is also the only known breeding site in the archipelago for Macronectes giganteus, of which a few pairs occur. The site holds very large populations of petrels, particularly Pachyptila belcheri as well as a small population of Phalacrocorax verrucosus. It is possible that numbers of breeding Pterodroma lessoni, Pachyptila desolata, P. belcheri, Pelecanoides georgicus, P. urinatrix Anas eatoni, Chionis minor and Sterna virgata exceed thresholds, but quantitative data are lacking.
Non-bird biodiversity: The site is one of the few places where the endemic plant Lyallia kerguelensis is still known to occur.
BirdLife International (2019) Important Bird Areas factsheet: Péninsule Rallier du Baty. Downloaded from http://www.birdlife.org on 22/03/2019.