Heather Angel / Giant panda (Ailuropoda melanoleuca) sliding down slope on back after losing footing. Panda Breeding Centre, Wolong, Sichuan, China. January 1987.

Ismaele Tortella / Eurasian otter (Lutra lutra) hunting in a shoal of Atlantic herring (Clupea harengus), northern Norway, March

Andy Rouse / African lion (Panthera leo) female carrying young cub, Masai Mara, Kenya, Africa. Highly commended in the African Wildlife Category of the Nature's Best Photography Competition 2019.

Diane McAllister / Polar bears (Ursus maritimus) fighting in water. Beaufort Sea , Kaktovik Alaska. USA. Highly commended in the Polar Passion category of the Nature's Best Photography Competition 2019.

Claudio Contreras / Californian sea lion (Zalophus californianus) swimming in Southern sea palm (Eisenia arborea) and Giant Kelp (Macrocystis pyrifera) forest, San Benitos Islands, Baja California Pacific Islands Biosphe...

Ann & Steve Toon / RF - Lion (Panthera leo) head portrait at night, Zimanga private game reserve, KwaZulu-Natal, South Africa. (This image may be licensed either as rights managed or royalty free.)

Danny Green / Polar bear (Ursus maritimus) walking across sea ice, reflected in water. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) female resting with cubs on glacier. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) female and cubs feeding on Whale carcass. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and two cubs feeding on Whale carcass. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs, standing on sea ice. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs resting on sea ice. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) female and cubs, one cub walking up slope of ice in foreground. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs feeding on Whale carcass. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs feeding on Whale carcass, on iceberg. Svalbard, Norway, July 2018.

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

Danny Green / Polar bear (Ursus maritimus) resting in snow. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) licking paw, close-up. Svalbard, Norway, April.

Danny Green / Polar bear (Ursus maritimus) standing on glacier. Svalbard, Norway, July 2018.

Danny Green / Polar bear (Ursus maritimus) standing on ice. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) looking for food on ice. Svalbard, Norway, April.

Danny Green / Polar bear (Ursus maritimus) male standing beside rocks in frozen and snow covered landscape. Svalbard, Norway, April 2019.

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 / Polar bear (Ursus maritimus), male and female approaching each other across snow covered rocky landscape. Svalbard, Norway, April 2019.

Danny Green / Polar bear (Ursus maritimus) male approaching female on snow covered hill top. Svalbard, Norway, April 2019.

Danny Green / Polar bear (Ursus maritimus) male approaching female in rocky area covered in snow. Svalbard, Norway, April 2019.

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

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 - 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 / Polar bear (Ursus maritimus) female and cubs play fighting. Svalbard, Norway, March 2018.

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) group on ice, female and cubs feeding on Whale carcass. Svalbard, Norway, June 2018.

Danny Green / Polar bear (Ursus maritimus) resting on sea ice, view from above. Svalbard, Norway, June 2018.

Danny Green / Polar bear (Ursus maritimus) sleeping in snow. Churchill, Manitoba, Canada, November.

Danny Green / Polar bear (Ursus maritimus) hunting Seal on sea ice. Svalbard, Norway, July 2018.

Danny Green / Polar bear (Ursus maritimus), two cubs playing, leaping across sea ice, reflected in water. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus), two cubs walking on sea ice. Svalbard, Norway, July.

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

Danny Green / Ringed seal (Pusa hispida) resting on ice, reflected in water. Svalbard, Norway. July.

Nick Garbutt / Puma (Puma concolor puma) young male standing with mouth open. Estancia Amarga, near Torres del Paine National Park, Patagonia, Chile. December.

Nick Garbutt / Western red panda (Ailurus fulgens fulgens) climbing in tree. Singalila National Park, India / Nepal border.

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.)

Ann & Steve Toon / Cheetah (Acinonyx jubatus) walking, silhouetted at dusk. Zimanga private game reserve, KwaZulu-Natal, South Africa.

Felis Images / Asiatic lion (Panthera leo persica), female and cubs in morning light, cub biting mother's leg. Gir National Park, Gujarat, India. Photo Phillip Ross/Felis Images

David Tipling / Grey seal (Halichoerus grypus) female in surf, Horsey, Norfolk, England, UK, February.

David Tipling / Grey seal (Halichoerus grypus) pup, Horsey, Norfolk, England, UK, February.

Ann & Steve Toon / Meerkats (Suricata suricatta) on the move, Kgalagadi Transfrontier Park, Northern Cape, South Africa, January. Second place in the Mammals Category of the GDT European Nature Photographer of the Year...

Andy Rouse / Bengal tiger (Panthera tigris) male, sub-adult aged three years, face portrait. Ranthambhore National Park, India.

Tony Heald / African wild dog (Lycaon pictus) portrait. Chobe National Park Botswana. Digitally enhanced sepia image.

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

Andy Rouse / Bengal Tiger (Panthera tigris) family drinking from pool, Ranthambhore, India

Jordi Chias / Crabeater seals (Lobodon carcinophaga) resting on ice floating ice sheet, Antarctic Peninsula, Antarctica.

Jordi Chias / Antarctic fur seal (Arctocephalus gazella), Antarctic Peninsula, Antarctica.

Jordi Chias / Antarctic fur seal (Arctocephalus gazella), Antarctic Peninsula, Antarctica.

Jordi Chias / Crabeater seals (Lobodon carcinophaga), Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) with mouth open, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx), Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) resting over an iceberg, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) resting over an iceberg, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) swimming underwater, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) resting over an iceberg, Antarctic Peninsula, Antarctica.

Jordi Chias / Crabeater seals (Lobodon carcinophaga) hunting under water, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) swimming, Antarctic Peninsula, Antarctica.

Jordi Chias / Antarctic fur seal (Arctocephalus gazella), Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) predating a Gentoo penguin (Pygoscelis papua) Antarctic Peninsula, Antarctica.

Jordi Chias / Weddell seal (Leptonychotes weddellii) hauled out on ice, Antarctic Peninsula, Antarctica.

Jordi Chias / Weddell seal (Leptonychotes weddellii), Antarctic Peninsula, Antarctica.

Jordi Chias / Weddell seal (Leptonychotes weddellii), Antarctic Peninsula, Antarctica.

Jordi Chias / Weddell seal (Leptonychotes weddellii), Antarctic Peninsula, Antarctica.

Ingo Arndt / Female Puma (Puma concolor) with two cubs aged around four months, Torres del Paine National Park, Patagonia, Chile, July.

Matthew Maran / Red fox (Vulpes vulpes) dog interacting with a vixen in an urban garden. North London, UK. June.

Matthew Maran / Red fox (Vulpes vulpes) dog interacting with a vixen in an urban garden. North London, UK. July.

Matthew Maran / Red fox (Vulpes vulpes) carrying a large dead Brown rat (Rattus norvegicus) in an urban garden, North London, UK. August.

Matthew Maran / Red fox (Vulpes vulpes) cub defending its kill (a large dead Brown rat (Rattus norvegicus)) from another cub, North London, UK. August.

Alex Mustard / California sea lion (Zalophus californianus) pups in an underwater cave. Los Islotes, La Paz, Baja California Sur, Mexico. Sea of Cortez, Gulf of California, East Pacific Ocean.

Staffan Widstrand / Jungle cat (Felis chaus) at night, Kanha National Park and Tiger Reserve, Madhya Pradesh, India

Alex Mustard / RF - Silhouette of a California sea lion (Zalophus californianus) swimming through an underwater cave. Los Islotes, La Paz, Baja California Sur, Mexico. Sea of Cortez, Gulf of California, East Pacific...

Lucas Bustamante / Giant river otter (Pteronura brasiliensis) eating a catfish. Yasuni National Park, Orellana, Ecuador

Lucas Bustamante / Sri Lankan leopard (Panthera pardus kotiya) rolling on its back, Yala National Park, Sri Lanka

Lucas Bustamante / Jaguar (Panthera onca) standing in mud, Yasuni National Park, Orellana, Ecuador

Oriol Alamany / Snow leopard (Panthera uncia) female with juvenile, walking in snow, in Spiti Valley, Cold Desert Biosphere Reserve, Himalaya, Himachal Pradesh, India, March

Oriol Alamany / Snow leopard (Panthera uncia) male in snow, in Spiti Valley, Cold Desert Biosphere Reserve, Himalaya, Himachal Pradesh, India, March

Oriol Alamany / Snow leopard (Panthera uncia) female (hiding below the rock) with her two juveniles resting in snow, in Spiti Valley, Cold Desert Biosphere Reserve, Himalaya, Himachal Pradesh, India, March

Ernie Janes / Cougar (Puma concolor) portrait, captive, occurs in the Americas. With digitally added leaves.

John Shaw / Common eider duck (Somateria mollissima) female defending her nest from arctic fox (Vulpes lagopus). Longyearbyen, Spitsbergen. June.

John Shaw / Cheetah (Acinonyx jubatus) stretches on a downed tree. Zimbabwe. September.

John Shaw / Brown bear (Ursus arctos) searching for clams on tidal mudflat with waterbirds. Lake Clark National Park, Alaska. August.

Andy Rouse / African Lion, (Panthera leo), female hunting, Masai Mara, Kenya, Africa,

Andy Rouse / Bengal Tiger, (Panthera tigris), walking, Ranthambhore, India

Andy Rouse / Galapagos sea lion, (Zalophus wollebaeki), pup on shore, Galapagos.

Andy Rouse / Red fox, (Vulpes vulpes), in bluebells, UK

Andy Rouse / Galapagos sea lion, (Zalophus wollebaeki), swimming upside down, Galapagos