Espen Bergersen / Aerial shot of a fishing boat with net full of Atlantic herring (Clupea harengus), with Killer whales (Orcinus orca) swimming around the outside, Skjervoy, Troms, Norway, November.

Espen Bergersen / Aerial shot of two Humpback whales (Megaptera novaeangliae) coming to the surface to breathe, Sommaroy, Troms, Norway, January.

Klein & Hubert / Siberian tiger (Panthera tigris altaica) running in snow. Controlled conditions.

Klein & Hubert / Grey wolf (Canis lupus) two running in the snow, USA. Controlled conditions.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two males, one brooding young chick, the other incubating hatching egg. Atka Bay, Antarctica. August. Series 4/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two males, one brooding young chick, the other incubating hatching egg. Atka Bay, Antarctica. August. Series 3/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two males, one brooding young chick, the other incubating hatching egg. Atka Bay, Antarctica. August. Series 2/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two males, one brooding young chick, the other incubating hatching egg. Atka Bay, Antarctica. August. Series 1/4.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) colony huddling, males incubating eggs, on sea ice under full moon in polar night. Atka Bay, Antarctica. July 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), four journeying across sea ice to feed young. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) preparing to jump over crack in sea ice. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) breeding colony on sea ice, ice shelf in background. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) group of brooding males amongst drifting snow. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) footprints on sea ice. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair practising incubating with a snowball. Atka Bay, Antarctica. May.

Stefan Christmann / Moon bow, a halo around the moon during polar night. Sastrugi on sea ice in foreground. Atka Bay, Antarctica. June.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair, female laying egg. Atka Bay, Antarctica. June.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair with recently laid egg, on sea ice. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) group sliding over ice, returning to form breeding colony. Atka Bay, Antarctica. April.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) group sliding over sea ice, returning to form breeding colony. Iceberg in background. Atka Bay, Antarctica. April 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) walking across crack in sea ice during return to breeding colony. Atka Bay, Antarctica. April.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) group sliding across sea ice to form breeding colony. Atka Bay, Antarctica. April 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) chicks aged 20-24 weeks stretching wings, in moult whilst parents fish at sea. Atka Bay, Antarctica. January.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), four chicks in moult aged 20-24 weeks, parents away fishing in open water. Atka Bay, Antarctica. January.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two adults brooding chicks. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), two adults brooding chicks. One chick exhibiting aggression towards other. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), breeding colony with individuals in foreground walking to / from open water. Atka Bay, Antarctica. September 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), three in a row, walking through drifting snow to feed young. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) standing in drifting snow, silhouetted by sun. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) adult brooding chick with two additional chicks seeking protection while parents are at sea. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) chick aged six to eight weeks, portrait. Atka Bay, Antarctica. September.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) group clambering up slope during journey to bring back food for young. Atka Bay, Antarctica. September.

Stefan Christmann / Cameraman Lindsay McCrae on sea ice filming frozen landscape and icebergfor BBC Dynasties Penguin programme. Atka Bay, Antarctica. October 2017.

Paul Hobson / Red deer (Cervus elaphus) stags in snowy Pine forest. Scotland, UK. March.

Pal Hermansen / Avalanche on Gullemot (Uria aalge) nesting cliff on first day birds return to breed. Finnmark, Norway. March.

Sven Zacek / White-tailed sea eagle (Haliaeetus albicilla) flying over frost and snow covered forest. Tartumaa, Southern Estonia. January 2011.

Klein & Hubert / Emperor penguin (Aptenodytes forsteri) chick, Antarctica.

Nick Garbutt / Male American Bison (Bison bison) walking through snow. Firehole River Valley, Yellowstone National Park, Wyoming, USA. January

Nick Garbutt / Pack of wolves (Canis lupus). Yellowstone National Park, Wyoming, USA. January.

Bence Mate / Great white egret (Ardea alba) group of three in winter, Kiskunsag National Park, Hungary. Winner of the Bird Category of Nature Photographer of the Year Awards 2018.

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding in snow, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Terry Whittaker / Arctic fox (Vulpes lagopus) feeding and digging in snow whilst hunting, blue colour morph, Hornstrandir Nature Reserve, Iceland, March.

Erlend Haarberg / European pine marten (Martes martes) on spring snow. Vauldalen, Norway, April.

Erlend Haarberg / Sunset in snow-covered mountain landscape. Okstindan, Fjell, Norway, February 2018.

Guy Edwardes / Snow covered tree, Northumberland, England. November 2010

David Tipling / Brown hares (Lepus europaeus) on snow covered field, Burnham Norton, Norfolk, England, UK. winter

David Tipling / Fieldfare (Turdus pilaris) in garden in freezing weather with snow on the ground Norfolk, England, UK. february