Possession Island

Possession Island is the largest of the five islands that make up the Crozet archipelago, rising steeply from the Southern Ocean with coastal cliffs that reach 200 to 300 metres on the western and southern shores. The island is volcanic in origin, the eroded remnant of a large stratovolcano whose central crater has been breached by the sea on the northern side. The landscape above the cliffs is a plateau of exposed basalt and glacial moraine, cut by streams that flow into the ocean in small waterfalls visible from the water.

The king penguin colony at Baie du Biso is the most dramatic wildlife spectacle on the island, a dense mass of breeding birds that stretches across the coastal plain near the French research station. The colony has been monitored continuously since the station was established in 1961, providing one of the longest individual-level datasets on any seabird population in the world. From the ridge above the colony the sound of the penguins is a constant, overlapping chorus that carries on the wind even when the birds themselves are out of sight.

The research station Alfred Faure occupies a sheltered valley on the northern shore and has been permanently staffed since 1961, making it one of the longest-running scientific bases in the subantarctic. The station supports research on penguin demography, marine mammal populations, and atmospheric chemistry. Access to the island is by a small boat from a ship that anchors off the coast; disembarkation depends entirely on sea conditions, which can change within minutes and make the shore inaccessible for days.

Four penguin species breed on Possession Island: king, macaroni, gentoo, and rockhopper. The king colony is by far the largest, with estimates ranging above one hundred thousand breeding pairs concentrated on the beaches of the eastern shore. Wandering albatrosses nest in the coastal tussock, and the island is one of the few places in the Crozet group where the Kerguelen shag breeds. The surrounding waters are heavily used by marine mammals; southern fur seals haul out on the southern beaches and whales are seen in the vicinity throughout the year.

Beyond the penguin colonies, Possession Island supports a rich assemblage of marine mammals that use the beaches and coastal waters throughout the year. Southern fur seals are present in large numbers during the summer breeding season, their haul-out beaches competing for space with the penguins on the eastern shore. Elephant seals breed on the beaches to the south of the station in smaller numbers, and both species are studied as part of the long-term marine mammal monitoring programme. At sea, the surrounding waters are frequented by sperm whales and several species of dolphin, and the ship-based surveys that depart from Alfred Faure station contribute to the growing picture of how Southern Ocean ecosystems are responding to changing sea temperatures and ice cover.

The king penguin colony at Baie du Biso is one of the largest single breeding concentrations of any penguin species on Earth.

The Alfred Faure research station has maintained continuous ecological and atmospheric records since 1961, a remarkable scientific legacy in such an isolated location.

The dramatic cliff scenery and coastal plateau offer outstanding views of the Southern Ocean and the island's wildlife from above.