Île de la Possession is the largest of the five Crozet Islands. Its mountainous landscape is cut by deep glaciated valleys. The valleys and coastal areas are covered in subantarctic vegetation. Black rats occur over most of the island. The island is uninhabited by man except for a research station on the eastern tip of the island, staffed by approximately 20 people.
See Box for key species. At least 28 species breed. In addition to those given below, these include 2,000 pairs of Pygoscelis papua, 1,150 pairs Phoebetria palpebrata and 84 pairs of Macronectes giganteus. Numbers of Anas eatoni and Chionis minor are believed to exceed thresholds, but no quantitative data are available. Ten pairs of Diomedea chrysostoma were recorded breeding in 1984. The smaller species breed only at higher altitudes due to the presence of rats lower down.
Non-bird biodiversity: Two species of fur seal breed on the island, Arctocephalus gazella and A. tropicalis, with respectively, 87 and 190 pups in 1991. Numbers have been increasing recently with the cessation of hunting. In 1997, 570 female Mirounga leonina bred. The coastal waters are inhabited by approximately 80 Orcinus orca (LR/cd). Two plants and 59 arthropod species endemic to the Îles Crozet occur.
BirdLife International (2019) Important Bird Areas factsheet: Île de la Possession. Downloaded from http://www.birdlife.org on 24/03/2019.