Brent Stephenson / Northern giant petrel (Macronectes halli) moving through water, off Kaikoura, Canterbury, New Zealand, November.

Barrie Britton / Southern Giant Petrel (Macronectes giganteus), St Andrew's Bay, South Georgia. Photograph taken on location for the BBC Frozen Planet series, October 2009.

Andy Trowbridge / Southern Giant Petrel (Macronectes giganteus) in flight off the coast of Kaikoura, Kaikoura, South Island, New Zealand. February.

Brent Stephenson / Northern Giant Petrel (Macronectes halli) with wings outstretched and tail cocked in threat display. Off Kaikoura, Canterbury, New Zealand, October.

Pete Oxford / Southern Giant Petrels (Macronectes giganteus) feeding on the carcass of a Southern Elephant seal bull, killed by Killer whales. Sea Lion Island. South of mainland east Falkland Island. Falkland Islan...

Michael Pitts / Southern giant petrel (Macronectes giganteus) head covered in blood feeding on carcass of an Elephant seal pup, with a penguin colony in the distance, St Andrews Bay, South Georgia

Hanne & Jens Eriksen / Southern Giant Petrel {Macronectes giganteus} resting on rocks, Antarctica.

Stefan Christmann / Giant petrel (Macronectes giganteus) in flight. Atka Bay, Antarctica. January.

Stefan Christmann / Giant petrel (Macronectes giganteus) in flight. Atka Bay, Antarctica. January.

Stefan Christmann / Giant petrel (Macronectes giganteus) in flight. Atka Bay, Antarctica. January.

Stefan Christmann / Giant petrel (Macronectes giganteus) in flight. Atka Bay, Antarctica. January.

Stefan Christmann / Giant petrel (Macronectes giganteus). Atka Bay, Antarctica. February.