Sebastian Kennerknecht / Minden / American Bison (Bison bison) female in winter, Yellowstone National Park, Wyoming

Donald M. Jones / Minden / Bighorn Sheep (Ovis canadensis) ram, western Canada

Klein & Hubert / Cape buffalo (Syncerus caffer) with Yellow-billed oxpckers (Buphagus africanus) drinking at waterhole in dry season, South Luangwa National Park, Zambia, Africa.

Richard Du Toit / Waterbuck (Kobus ellipsiprymnus) Kruger National Park, Limpopo Province, South Africa.

Danny Green / Bison (Bison bison) in snow, at woodland edge with frost covered trees. Yellowstone National Park, USA, January 2020.

Danny Green / Big horn sheep (Ovis canadensis) male looking down from snowy ledge, portrait. Yellowstone National Park, USA, January.

Tony Heald / African buffalo (Syncerus caffer) herd showing defensive behaviour as an African lioness (Panthera leo) walks by, Mana Pools National Park, Zimbabwe. September....

Tony Heald / Lion (Panthera leo) moving away from a defensive African buffalo (Syncerus caffer) Mana Pools National Park, Zimbabwe.

Erlend Haarberg / Muskox (Ovibus moschatos) males, Dovrefjell-Sunndalsfjella National Park, Norway, February.

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

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

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

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.

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

Nick Garbutt / RF - Skull of a male Himalayan ibex (Capra sibirica) (killed by a snow leopard) lying on steep rocky slope. Himalayas, Ladakh, northern India. (This image may be licensed either as rights managed or r...

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

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

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

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

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

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

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 / 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.

Danny Green / RF - Bison (Bison bison) breathing in the cold air, Yellowstone National Park, USA, February (This image may be licensed either as rights managed or royalty free.)

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

Klein & Hubert / Ibex (Capra ibex) female with kid on rock wall, Alps, Switzerland.

Ann & Steve Toon / Common wildebeest (Connochaetes taurinus) with reflection at waterhole, Zimanga private game reserve, KwaZulu-Natal, South Africa, September

Ann & Steve Toon / Sable (Hippotragus niger), Chobe National Park, Botswana, June

Ann & Steve Toon / Cape buffalo (Syncerus caffer) at waterhole at night with plains zebra (Equus quagga), Zimanga private game reserve, KwaZulu-Natal, South Africa, September

Ann & Steve Toon / Cape buffalo (Syncerus caffer) drinking at waterhole at night, Zimanga private game reserve, KwaZulu-Natal, South Africa, September

Ann & Steve Toon / Cape buffalo (Syncerus caffer) drinking at waterhole at night, Zimanga private game reserve, KwaZulu-Natal, South Africa, September

Ann & Steve Toon / RF - Leopard female (Panthera pardus) watched by two Gemsbok (Oryx gazella), Kgalagadi transfrontier park, South Africa, June. (This image may be licensed either as rights managed or royalty free.)

Inaki Relanzon / Arabian Oryx (Oryx leucoryx) at sunset. Previously extinct in the wild, their conservation status is now stable thanks to conservation efforts.This male is part of a reintroduction program in Dubai, U...

Danny Green / Bison (Bison bison) herd walking in line in snow, Yellowstone National Park, Wyoming, USA, February

Nick Garbutt / Herd of American bison (Bison bison) in snow, Yellowstone National Park, Wyoming, Yellowstone, January.