Snow petrel (Pagodroma nivea) in flight against a dark blue sea, South Georgia and South Sandwich Islands, Polar Regions

Southern Giant Petrel (Macronectes giganteus) on the wing in and around the Antarctic Peninsula. (rr)

Southern Giant Petrel (Macronectes giganteus) on the wing in and around the Antarctic Peninsula.

Southern Giant Petrel (Macronectes giganteus) on the wing in and around the Antarctic Peninsula. (rr)

Southern Giant Petrel (Macronectes giganteus) on the wing in and around the Antarctic Peninsula.

A Buller's Albatross rests on the water off the coast of Wollongong, New South Wales, Australia

Search for a Blue Petrel (Halobaena caerulea) in a burrow that has been monitored for several years or even decades on ile Verte. Gulf of Morbihan, Kerguelen archipelago.

Precise measurement of the leg length of a Blue Petrel (Halobaena caerulea) after banding, as part of an annual monitoring program over several decades on ile Verte. Gulf of Morbihan, Kerguelen archipelago.

The two ornithologists take the Blue Petrels (Halobaena caerulea) being monitored from their burrows, then release them there after carrying out the required measurements. Gulf of Morbihan, Mayes Island, Kerguelen archipelago.

Blue Petrel footprints in the snow. Mayes Island, Gulf of Morbihan. Kerguelen Archipelago.

Measuring the wing of a Blue Petrel (Halobaena Caerulea). Mayes Island, Gulf of Morbihan. Kerguelen Archipelago.

Reading the ring. The ornithologist delicately places a ring on the leg of the Blue Petrel (Halobaena caerulea). Gulf of Morbihan, Mayes Island, Kerguelen archipelago.