Ismaele Tortella / Four Eurasian elk (Alces alces) walking through vegetation , Norway, August

Ismaele Tortella / Svalbard reindeer (Rangifer tarandus platyrhynchus) feeding in snow, Svalbard, Norway, March.

Ismaele Tortella / Reindeer (Rangifer tarandus), Kvaloya island, Tromso, Norway, November.

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 / 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.

Daniel Heuclin / Llama (Lama glama) Laguna colorada. Altiplano, Bolivia.

Daniel Heuclin / Llama (Lama glama) herd, Laguna colorada. Altiplano, Bolivia.

Nick Garbutt / Guanaco (Lama guanicoe) standing, towers of Torres del Paine National Park in background. Patagonia, Chile. December 2018.

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

Gabriel Rojo / Guanaco (Lama guanicoe) female and newborn baby, nose to nose in grassland. La Pampa Province, Argentina.

Staffan Widstrand / Southern Giraffe (Giraffa camelopardalis) two, with one in foreground, Zimanga Private Nature Reserve, KwaZulu Natal, South Africa

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

Oscar Dewhurst / Red deer (Cervus elaphus) stag roaring, silhouetted under trees at sunrise. Bushy Park, London, UK. September

Jack Dykinga / Bighorm sheep (Ovis canadensis) males grouped together before the rutting season. Valley of Fire State Park, Nevada, USA, February.

Ingo Arndt / Close-up of a Guanaco (Lama guanicoe) feeding, Torres del Paine National Park, Patagonia, Chile, December.

Ingo Arndt / Aerial shot over a herd of Guanacos (Lama guanicoe), Torres del Paine National Park, Patagonia, Chile, April.

David Woodfall / Red Deer (Cervus elaphus) portrait of head of stag and antlers. Alladale Estate, Scotland, UK, October.

David Woodfall / Red deer (Cervus elaphus) on moorland / blanket bog silhouetted against rushes, Alladale Estate, Scotland, UK, October.

Yashpal Rathore / Bengal tiger (Panthera tigris tigris) tigress (T32) feeding on Spotted deer / Chital (Axis axis) killed by her earlier that day while her young cub watches. Kanha National Park, Central India. Camera...

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

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 / Red deer, (Cervus elaphus), stag in rough grassland, Jura, Scotland, UK., April

David Pattyn / Alpine ibex (Capra ibex) adult males fighting in alpine landscape, Valsavarenche, Gran Paradiso National Park, Aosta Valley, Italy, May

David Pattyn / Alpine Ibex (Capra ibex) in its landscape, Valsavarenche, Gran Paradiso national park, Aosta Valley, Italy, May

David Pattyn / Alpine ibex (Capra ibex) struggling in deep snow on a steep slope, Valsavarenche, Gran Paradiso National Park, Aosta Valley, Italy, January

Eric Baccega / Female Uganda kob (Kobus kob thomasi) suckling calf. Murchisson Falls National Park, Uganda. February.

Jed Weingarten / Wild Wonders of China / Takin (Budorcas taxicolor) Tangjiahe Nature Reserve, Sichuan Province, China. April.

Jed Weingarten / Wild Wonders of China / White-lipped deer (Cervus albirostris) stags in mountain landscape, Serxu County, Garze Prefecture, Sichuan Province, China.

Jed Weingarten / Wild Wonders of China / Snow leopard (Uncia uncia) with Bharal (Pseudois nayaur) prey, Serxu County, Garze Prefecture, Sichuan Province, China.

Jed Weingarten / Wild Wonders of China / White-lipped deer (Cervus albirostris) male, Serxu, Garze Prefecture, Sichuan Province, China

Jed Weingarten / Wild Wonders of China / Injured Muntjac (Muntiacus reevesi) swimming in a small creek after unsuccessfully attempting to jump across it. This muntjac was unable to get out of the creek himself, and was later rescued by the p...

Staffan Widstrand / Wild Wonders of China / Pere David's deer / Milu (Elaphurus davidianus) male walking in the morning,Hubei Tian'ezhou Milu National Nature Reserve, Shishou, Hubei, China

Staffan Widstrand / Wild Wonders of China / Pere David's deer / Milu (Elaphurus davidianus) stag, walking in the morning in Hubei Tian'ezhou Milu National Nature Reserve, Shishou, Hubei, China

Staffan Widstrand / Wild Wonders of China / Pere David's deer / Milu (Elaphurus davidianus), two stags testing their strength in Hubei Tian'ezhou Milu National Nature Reserve, Shishou, Hubei, China

Staffan Widstrand / Wild Wonders of China / Pere David's deer / Milu (Elaphurus davidianus), walking through water of Yangtze river, Hubei Tian'ezhou Milu National Nature Reserve, Shishou, Hubei, China

Staffan Widstrand / Wild Wonders of China / Pere David's deer / Milu (Elaphurus davidianus) stag wading through the water of the Yangtze river, Hubei Tian'ezhou Milu National Nature Reserve, Hubei, China

Alex Hyde / Guanaco (Lama guanicoe) grazing on grassland plain, Patagonia, Chile. Novmeber.

Sven Zacek / Wild boar (Sus scrofa) swimming with head above water in Suur Emajogi River. Alam-Pedja Nature Reserve, Tartumaa, Southern Estonia. November.

Sven Zacek / Roe deer (Capreolus capreolus) young buck, portrait. Karula National Park, Valgamaa, Southern Estonia. June.

Anup Shah / Mixed herd of Common or Plains zebra (Equus quagga burchellii) and Eastern white-bearded wildebeest (Connochaetes taurinus) - remote camera. Masai Mara National Reserve, Kenya.

Daniel Heuclin / Vicuna (Vicugna vicugna), five running across salt flat with mountain in background. Salar de Ascotan, Chile. September 2018.

Guy Edwardes / Misty landscape with Red deer (Cervus elaphus) Black Mount, Highlands, Scotland, November.

Paul Hobson / Red deer (Cervus elaphus) herd during rut in morning light. Derbyshire, England, UK. October.

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

SCOTLAND: The Big Picture / Red deer (Cervus elaphus) stag in upland landscape. Lochcarron, Highlands, Scotland, UK.

SCOTLAND: The Big Picture / Red deer (Cervus elaphus) stag in upland landscape. Lochcarron, Highlands, Scotland, UK.

Ann & Steve Toon / Impala (Aepyceros melampus) allo-grooming, iMfolozi game reserve, KwaZulu-Natal, South Africa, August

Enrique Lopez-Tapia / Tourists riding Bactrian camels (Camelus bactrianus) in sand dunes, Nubra Valley. Ladakh, India, September 2018.

Enrique Lopez-Tapia / Man leading Bactrian camels (Camelus bactrianus) in sand dunes, Nubra Valley. Ladakh,,India, September 2018.

Ann & Steve Toon / Giraffe (Giraffa camelopardalis) drinking at night, Zimanga private game reserve, KwaZulu-Natal, South Africa August

Enrique Lopez-Tapia / Bactrian camels (Camelus bactrianus) on sand, Nubra Valley, Ladakh, India. September.

Loic Poidevin / Alpine ibex (Capra ibex) female, Jura, Switzerland, September.

Axel Gomille / Red deer (Cervus elaphus) stag, Saxony, Germany. September.

Erlend Haarberg / Semi-domesticated reindeer (Rangifer tarandus) walking on snow-covered road in pine forest. Lapland, Sweden. February.

Erlend Haarberg / Herd of wild Reindeer (Rangifer tarandus) in snow-covered mountain landscape, in wind storm. Forollhogna, Norway. January 2018.

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

Paul Williams / Moose (Alces alces) female with twin calves, Baxter State Park, Maine, USA, June.

Philippe Clement / Pair of Roe deer (Capreolus capreolus) resting and grazing in forest in summer, France, September.

Sandesh Kadur / Blue wildebeest (Connochaetes taurinus) crossing a river, Serengeti National Park, Tanzania.

Stephane Granzotto / Alpine ibex (Capra ibex) feeding in deep snow, digging to reach food, Rhone-Alpes, France, December.

Staffan Widstrand / Wild Wonders of China / Sichuan / Tibetan takin (Budorcas taxicolor tibetana) walking through a forest in Tangjiahe National Nature Reserve,Qingchuan County, Sichuan province, China

Valeriy Maleev / Siberian musk deer (Moschus moschiferus) male, Irkutsk, Russia. March.

Tony Heald / Hippopotamus (Hippopotamus amphibius) splashing in pool in evening light. Mana Pools National Park, Zimbabwe.

Ann & Steve Toon / Springbok (Antidorcas marsupialis) herd fleeing predator, Kgalagadi Transfrontier Park, South Africa.

Guy Edwardes / Hippopotamus (Hippopotamus amphibius) in Chobe River, Botswana.

Guy Edwardes / Red-billed oxpecker (Buphagus erythrorhynchus) feeding on Impala (Aepyceros melampus), Savuti, Botswana.

Denis-Huot / Masai giraffe (Giraffa camelopardalis tippelskirchi), female and calf at sunset, with Abdim's storks in flight, Masai-Mara Game Reserve, Kenya

Jim Manthorpe / American bison (Bison bison) feeding, Yellowstone National Park, Wyoming, USA, August.

Nick Garbutt / Urial sheep (Ovis vignei) herd running across steep barren slopes. Himalayas near Ulley, Ladakh, India.

Dave Bevan / Juvenile male Wild boar (Sus scrofa) fighting to establish seniority, Gloucestershire, England, UK, December.

Philippe Clement / Red deer (Cervus elaphus) stags fighting, Scotland, UK, May.

Luke Massey / Wild boar (Sus scrofa) piglets suckling from mother, Forest of Dean, Gloucestershire, England, UK, May.

Luke Massey / Wild boar (Sus scrofa) piglets resting, with mother nearby, Forest of Dean, Gloucestershire, England, UK, May.

Luke Massey / Low angle shot of Wild boar (Sus scrofa) piglets running towards parent, Forest of Dean, Gloucestershire, England, UK, May.

Luke Massey / Two Wild boar (Sus scrofa) feeding in woodland with piglets, Forest of Dean, Gloucestershire, England, UK, May.

Luke Massey / Close-up of a Wild boar (Sus scrofa) piglet feeding, Forest of Dean, Gloucestershire, England, UK, May.

Luke Massey / Close-up of a Wild boar (Sus scrofa) approaching a remote camera and knocking it over, Forest of Dean, Gloucestershire, England, UK, May.

Claudio Contreras / Young girl face to face with Peninsular Pronghorn Antelope (Antilocapra americana peninsularis) fawn at Peninsular Pronghorn recovery project, El Vizcaino Desert Biosphere Reserve, Baja California Pen...

Bence Mate / African buffalo (Syncerus caffer) at waterhole at night, Mkuze, South Africa Third place in the Nature Portfolio category of the World Press Photo Awards 2017.

Bence Mate / Fallow deer (Dama dama) at night, Gyulaj, Hungary Third place in the Nature Portfolio category of the World Press Photo Awards 2017.

Bence Mate / Fallow deer (Dama dama) at night, Gyulaj, Hungary Third place in the Nature Portfolio category of the World Press Photo Awards 2017.

Bence Mate / African buffalo (Syncerus caffer) and Warthog (Phacochoerus africanus) at night with full moon, Mkuze, South Africa Third place in the Nature Portfolio category of the World Press Photo Awards 2017.

Bence Mate / African buffalo (Syncerus caffer) at waterhole at night, Mkuze, South Africa Third place in the Nature Portfolio category of the World Press Photo Awards 2017.

Bence Mate / Hippopotamus (Hippopotamus amphibius) at waterhole at night, Mkuze, South Africa Third place in the Nature Portfolio category of the World Press Photo Awards 2017.

Ann & Steve Toon / Impala (Aepyceros melampus) with redbilled oxpecker (Buphagus erythrorhynchus), Kruger National Park, South Africa.

Edwin Giesbers / Close-up of a litter of Wild boar (Sus scrofa) piglets sleeping on top of their mother, with another piglet joining, Germany, January. Captive.

Edwin Giesbers / Close-up of a litter of Wild boar (Sus scrofa) piglets sleeping on top of their mother, with another piglet joining, Germany, January. Captive.