Ismaele Tortella / Three Rock ptarmigan (Lagopus muta) feeding in winter plumage, city of Tromso in the background, northern Norway, March 2019.

Ismaele Tortella / Aerial tracking shot over Tromso in the winter, northern Norway, March 2019.

Danny Green / Polar bear (Ursus maritimus) walking across ice, snow covered mountain in background. Svalbard, Norway, April 2018.

Danny Green / Polar bear (Ursus maritimus) male walking across frozen landscape. Svalbard, Norway, April 2019.

Danny Green / Polar bear (Ursus maritimus) male in snow. Svalbard, Norway, April.

Danny Green / Arctic fox (Vulpes lagopus), two in snow covered landscape. Svalbard, Norway, April 2019.

Danny Green / Arctic fox (Alopex lagopus) standing on ice, in winter pelage. Svalbard, Norway, April.

Danny Green / RF - Polar bear (Ursus maritimus) male walking through snow covered landscape, mountains in background. Svalbard, Norway, April (This image may be licensed either as rights managed or royalty free.)

Danny Green / RF - Arctic fox (Alopex lagopus) in winter pelage, camouflaged in snow. Svalbard, Norway, April (This image may be licensed either as rights managed or royalty free.)

Danny Green / RF - Reindeer (Rangifer tarandus) walking up slope in snow. Svalbard, Norway, April. (This image may be licensed either as rights managed or royalty free.)

Danny Green / RF - Polar bear (Ursus maritimus) cub walking in snow. Svalbard, Norway, April. (This image may be licensed either as rights managed or royalty free.)

Danny Green / RF - Polar bear (Ursus maritimus) female walking across ice. Svalbard, Norway, April. (This image may be licensed either as rights managed or royalty free.)

Danny Green / Ringed seal (Pusa hispida) and pup resting on ice. Svalbard, Norway. April.

Danny Green / Reindeer (Rangifer tarandus), two standing on ridge in blizzard. Svalbard, Norway. April.

Danny Green / Reindeer (Rangifer tarandus), two play fighting in snow. Svalbard, Norway, April.

Danny Green / Reindeer (Rangifer tarandus), two standing on ridge in snow. Svalbard, Norway, April.

Danny Green / Reindeer (Rangifer tarandus) standing on ridge in snow, another reindeer in background. Svalbard, Norway, April.

Danny Green / Reindeer (Rangifer tarandus) hunkering down in snow during blizzard. Svalbard, Norway, April.

Danny Green / Reindeer (Rangifer tarandus) walking in snow. Svalbard, Norway, April.

Danny Green / Polar bear (Ursus maritimus) two walking in snowy landscape. Svalbard, Norway, April 2018.

Danny Green / Polar bear (Ursus maritimus) male female pair looking upwards, snow covered hills in background. Svalbard, Norway, April 2018.

Danny Green / Polar bear (Ursus maritimus) cub ready to jump down from pack ice. Svalbard, Norway, April.

Danny Green / Arctic fox (Alopex lagopus) following scent, in winter pelage. Svalbard, Norway. April.

Danny Green / Arctic fox (Alopex lagopus) camouflaged in winter pelage. Svalbard, Norway, April.

Danny Green / Arctic fox (Alopex lagopus) in snow. Svalbard, Norway. April.

Nick Garbutt / American bison (Bison bison) female covered in hoar frost near hot spring, portrait. Midway Geyser Basin, Yellowstone National Park, USA. February.

Nick Garbutt / RF - Red fox (Vulpes vulpes) foraging in snow covered valley. Hayden Valley, Yellowstone National Park, USA. February 2019. (This image may be licensed either as rights managed or royalty free.)

Ingo Arndt / Sun rising over ice formations on Lake Baikal. Siberia, Russia. February 2019.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) colony huddled together under the Southern Lights, Aurora australis, Atka Bay, Antarctica. September.

Theo Bosboom / Winter landscape at Luskentyre beach, Isle of Lewis, Scotland, North Harris in the background. February 2018.

Theo Bosboom / Powerful waves rolling in at the Atlantic coast of Iceland near Dyrholey during a powerful winter storm. February 2016

Theo Bosboom / Sand patterns at sunrise, Praia da Adraga, Sintra, Portugal. December 2016

Theo Bosboom / Blue hour before sunrise over the dunes of Seilebost beach, Isle of Harris, Hebrides, Scotland. February 2018.

Theo Bosboom / Winter sunsrise at Seilebost beach, Isle of Harris, Scotland. February 2018

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) egg hatching on father's feet. Atka Bay, Antarctica. August. Winner of the Portfolio category of the Wildlife Photographer of the Year Awards 2019.

Sven Zacek / Ural owl (Strix uralensis) hunting, Tartumaa county, Southern Estonia.

Heather Angel / Giant panda (Ailuropoda melanoleuca) portrait, in falling snow. Captive bred, in enclosure, Panda Breeding Centre, Wolong, Sichuan Province, China. February 2008.

Oscar Dewhurst / Fallow deer (Dama dama) walking across frost-covered playing fields at dawn, with tower blocks of London in the background. Richmond Park, London, UK. December

Mark Raycroft / Pronghorn Antelope (Antilocapra americana) running in winter, North America

Mark Raycroft / Pronghorn Antelope (Antilocapra americana) running in winter, North America

Loic Poidevin / Eurasian bullfinch (Pyrrhula pyrrhula) male on a branch feeding on Rowan (Sorbus aucuparia) berries, Leon, Spain, February.

Loic Poidevin / Eurasian bullfinch (Pyrrhula pyrrhula) male on a branch feeding on Rowan (Sorbus aucuparia) berries, Leon, Spain, February.

Jack Dykinga / Inspiration point covered in snow, Bryce Canyon National Park, USA, January.

Jack Dykinga / Landscape of hoodoos in snow at sunrise, Bryce Canyon National Park, Utah, USA, January.

Jack Dykinga / Winter snow storms cause wind-blown drifting along the canyon rim, Bryce Canyon National Park, Utah, USA, January.

Jack Dykinga / Conifer tree branch covered in snow and frost from winter snow storm. Bryce Canyon National Park, Utah, USA, January.

Jack Dykinga / Bryce Canyon National Park, Utah. Bristlecone pine clinging to the canyon rim at dawn, Bryce Canyon National Park, Utah, USA, January.

Ernie Janes / Beech trees (Fagus sylvatica) at night in winter, with lamp post illuminating the woodland. Felbrigg Woods, Norfolk, England, UK. January.

Jeff Foott / Turret Arch in winter, La Sal Mountains, Arches National Park, Utah

Jeff Foott / Marching Men sandstone formation, Arches National Park, Utah

Jeff Foott / Winding road and sandstone formations, La Sal Mountains, Arches National Park, Utah

David Woodfall / Strips of cultivated Black oats (Avena strigosa) , grown by crofters ,who create sillage and feed it to their cattle in the winter. Berneray, North Uist, Scotland, UK, July.

John Shaw / Pine tree (Pinus sp) in winter, Bryce Canyon National Park, Utah, USA, January.

Colin Monteath/ Hedgehog House / Icebergs in winter in lake, Hooker Glacier, Mount Cook, Mount Cook National Park, New Zealand

SCOTLAND: The Big Picture / Red deer, (Cervus elaphus), stags silhouetted at sunset in winter, Scotland, UK.February

SCOTLAND: The Big Picture / Red deer, (Cervus elaphus), stags silhouetted at sunset in winter, Scotland, UK.February

SCOTLAND: The Big Picture / Mountain hare, (Lepus timidus), four animals on snowy hillside in winter, Scotland, UK, February.

SCOTLAND: The Big Picture / Mountain hare footprints in snow on mountain top in Glen Coe, Lochaber, Scotland, UK.February

SCOTLAND: The Big Picture / River Spey on winter's dawn, Cairngorms National Park, Scotland, UK.January

SCOTLAND: The Big Picture / Buacaille Etive Mor and River Etive in winter, Rannoch Moor, Glencoe, Scotland, UK.December

SCOTLAND: The Big Picture / Turnstones (Arenaria interpres) and Purple sandpipers (Calidris maritima) over wintering on the beaches of the Orkney Isles, Scotland, UK, April.

Oscar Dewhurst / Red fox (Vulpes vulpes) sitting on a frozen lake at the edge of the reeds. London, UK. December.

Oscar Dewhurst / Red Fox (Vulpes vulpes) running through deep snow. London, UK. January

Oscar Dewhurst / Red Fox (Vulpes vulpes), hunting in the frost, London, UK. November

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.

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Marie Read / Snow buntings (Plectrophenax nivalis) flock in flight during a snowstorm, New York, USA, January.

Marie Read / Snowy Owl (Nyctea scandiaca) female perched, Amherst Island, Ontario, Canada, January.

Marie Read / California quail (Callipepla californica), male emerging from behind snowbank in winter, Mono Lake Basin, California, USA

Marie Read / Loggerhead shrike (Lanius ludovicianus) on an ice-covered fence after an ice storm, Anahuac National Wildlife Refuge, Texas, USA. January.

Marie Read / Northern cardinal (Cardinalis cardinalis) male perched amid snow-covered branches, New York, USA, February.

Marie Read / Common redpoll (Carduelis flammea), male perched in alder (Alnus rugosa) during a snowstorm in winter, New York, USA, January.

Marie Read / American Robin (Turdus migratorius), feeding on winterberry (Ilex) fruits in winter, New York, USA, December.

David Pattyn / Bearded vulture (Gypaetus barbatus) in flight over winter landscape with snow, Leukerbad, Vallais, Wallis, Switzerland, January

David Pattyn / Bearded vulture (Gypaetus barbatus) in flight over winter landscape with snow, Leukerbad, Vallais, Wallis, Switzerland, January

Markus Varesvuo / Black woodpecker (Dryocopus martius) male perched on tree trunk, trees covered in hoar frost. Kuusamo, Northern Ostrobothnia, Finland. February. Commended in the Birds in the Environment Category of t...

Staffan Widstrand / Golden eagle (Aquila chrysaetos) perched in snow covered tree. Kalvtrask, Vasterbotten, Lapland, Sweden. January.

Staffan Widstrand / Golden eagle (Aquila chrysaetos) in flight over snow. Kalvtrask, Vasterbotten, Lapland, Sweden. January.

Jeff Foott / Waterfall in winter, Horsetail Fall, Yosemite National Park, California

Jeff Foott / Waterfall in winter, Lower Yosemite Falls, Yosemite National Park, California

John Waters / Large group of Pied wagtails (Motacilla alba) roosting in a Plane tree (Platanus hispanica), Bath, England, UK, January.

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) breeding colony, males huddling on sea ice during polar night, incubating eggs, ice shelf in background. Atka Bay, Antarctica. July 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) colony huddled during polar night, males incubating eggs. Atka Bay, Antarctica. July 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) colony, males huddling whilst incubating eggs. Atka Bay, Antarctica. July.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) colony, males huddling whilst incubating eggs. Atka Bay, Antarctica. July.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri), group of three males incubating, one with begging chick. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) males in breeding colony huddling during winter storm. Atka Bay, Antarctica. July.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair transferring recently laid egg from female to male. 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) males huddling whilst incubating eggs,under full moon during polar night, Atka Bay, Antarctica. July.