Jami Tarris / Bactrian Camel (Camelus bactrianus) herd led by herder over snow-covered dunes in winter, Gobi Desert, Mongolia

Jami Tarris / Mongolian Horse (Equus caballus) herd in winter, Gobi Desert, Mongolia

Jami Tarris / Bactrian Camel (Camelus bactrianus) with herder in winter, Gobi Desert, Mongolia

Jami Tarris / Bactrian Camel (Camelus bactrianus) herd led by herder over dunes in winter, Gobi Desert, Mongolia

Jami Tarris / Bactrian Camel (Camelus bactrianus) in winter at sunset, Gobi Desert, Mongolia

Mark Raycroft / American Marten (Martes americana) in winter, North America

Mark Raycroft / White-tailed Deer (Odocoileus virginianus) buck with one antler in winter, North America

Ralf Kistowski/ BIA / Egyptian Goose (Alopochen aegyptiacus) pair fighting in winter, North Rhine-Westphalia, Germany

Ralf Kistowski/ BIA / Greylag Goose (Anser anser) in winter, North Rhine-Westphalia, Germany

Donald M. Jones / Spruce Grouse (Falcipennis canadensis) male in winter, Montana

Donald M. Jones / Spruce Grouse (Falcipennis canadensis) female on snow, Montana

Donald M. Jones / Red Squirrel (Tamiasciurus hudsonicus) in winter, Montana

Donald M. Jones / Red Squirrel (Tamiasciurus hudsonicus) in winter, Montana

Donald M. Jones / Mountain Cottontail (Sylvilagus nuttallii) in winter, Montana

Donald M. Jones / Mountain Chickadee (Poecile gambeli) in winter, Montana

Donald M. Jones / European Partridge (Perdix perdix) trio in winter, Montana

Donald M. Jones / European Partridge (Perdix perdix) in winter, Montana

Donald M. Jones / Elk (Cervus elaphus) bull rubbing sapling in winter, Alberta, Canada

Donald M. Jones / Elk (Cervus elaphus) female on railroad tracks in winter, Alberta, Canada

Donald M. Jones / Elk (Cervus elaphus) females grazing along railroad tracks in winter, Alberta, Canada

Donald M. Jones / Downy Woodpecker (Picoides pubescens) female in winter, Montana

Donald M. Jones / Canada Goose (Branta canadensis) flock landing in winter, Mission Valley, Montana

Donald M. Jones / Canada Goose (Branta canadensis) flock landing in winter, Mission Valley, Montana

Donald M. Jones / Bighorn Sheep (Ovis canadensis) ram, females, and lamb in winter, Jasper National Park, Alberta, Canada

Donald M. Jones / Bighorn Sheep (Ovis canadensis) ram grazing on dry grass in winter, Canada

Donald M. Jones / Bighorn Sheep (Ovis canadensis) ram and female in winter, Jasper National Park, Alberta, Canada

Donald M. Jones / Bighorn Sheep (Ovis canadensis) rams and females in winter, Jasper National Park, Alberta, Canada

Chase Dekker / American Marten (Martes americana) in snow, Algonquin Provincial Park, Ontario, Canada

Ingo Arndt / Mountain Lion (Puma concolor) tracks in snow, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Long-tailed Meadowlark (Leistes loyca) in winter, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Mountain Lion (Puma concolor) tracks in snow, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Mountain Lion (Puma concolor) tracks in snow, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Mountain Lion (Puma concolor) tracks in snow, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Mountain Lion (Puma concolor) female in snow, Torres del Paine National Park, Patagonia, Chile

Ingo Arndt / Bearded Vulture (Gypaetus barbatus) flying in winter, Valais, Switzerland

Ingo Arndt / Bearded Vulture (Gypaetus barbatus) flying in winter, Valais, Switzerland

Ingo Arndt / Bearded Vulture (Gypaetus barbatus) flying in winter, Valais, Switzerland

Ingo Arndt / Bearded Vulture (Gypaetus barbatus) flying in winter, Valais, Switzerland

Ingo Arndt / Bearded Vulture (Gypaetus barbatus) flying in winter, Valais, Switzerland

Ingo Arndt / White-winged Snowfinch (Montifringilla nivalis) in winter, Valais, Switzerland

Ingo Arndt / Alpine Accentor (Prunella collaris) in winter, Valais, Switzerland

Ingo Arndt / Alpine Accentor (Prunella collaris) in winter, Valais, Switzerland

Ingo Arndt / Alpine Accentor (Prunella collaris) in winter, Valais, Switzerland

Ingo Arndt / Mountain Lion (Puma concolor) female in snow, Torres del Paine National Park, Patagonia, Chile

Chase Dekker / American Marten (Martes americana) in snow, Algonquin Provincial Park, Ontario, Canada

Chase Dekker / Blue Jay (Cyanocitta cristata) in snowfall, Algonquin Provincial Park, Ontario, Canada

Chase Dekker / Blue Jay (Cyanocitta cristata) in snowfall, Algonquin Provincial Park, Ontario, Canada

Chase Dekker / Red Squirrel (Tamiasciurus hudsonicus) feeding in snow, Algonquin Provincial Park, Ontario, Canada

Chase Dekker / Red Squirrel (Tamiasciurus hudsonicus) feeding in winter, Algonquin Provincial Park, Ontario, Canada

Chase Dekker / American Marten (Martes americana) in snow, Algonquin Provincial Park, Ontario, Canada

Chase Dekker / American Marten (Martes americana) in snow, Algonquin Provincial Park, Ontario, Canada

Marion Vollborn/ BIA / Whooper Swan (Cygnus cygnus) taking flight on snow, Hokkaido, Japan

Marion Vollborn/ BIA / Whooper Swan (Cygnus cygnus) flock on snow, Hokkaido, Japan

Mark Raycroft / German Shepherd (Canis familiaris) in winter, North America

Mark Raycroft / Flat-coated Retriever (Canis familiaris) in winter, North America

Mark Raycroft / French Bulldog (Canis familiaris) in winter, North America

Scott Leslie / Cedar Waxwing (Bombycilla cedrorum) feeding on Virginia Winterberry (Ilex verticillata) berries during snowfall, North America

Scott Leslie / Cedar Waxwing (Bombycilla cedrorum) feeding on Virginia Winterberry (Ilex verticillata) berries during snowfall, North America

Sergey Gorshkov / Sable (Martes zibellina) in tree stump, Putoransky State Nature Reserve, Putorana Plateau, Siberia, Russia

Sergey Gorshkov / Sable (Martes zibellina) on tree, Putorana Plateau, Siberia, Russia

Mark Raycroft / White-tailed Deer (Odocoileus virginianus) buck in winter, North America

Mark Raycroft / Bighorn Sheep (Ovis canadensis) rams in winter, North America

Mark Raycroft / Bighorn Sheep (Ovis canadensis) ram, North America

Mark Raycroft / White-tailed Deer (Odocoileus virginianus) buck in winter, North America

Hiroya Minakuchi / Japanese Macaque (Macaca fuscata) on branch in winter, Jigokudani, Japan

Mark Raycroft / Jack Russell Terrier (Canis familiaris) male running in snow

Mark Raycroft / Golden Retriever (Canis familiaris) with puppy in snow

Mark Raycroft / Golden Retriever (Canis familiaris) with puppy in snow

Mark Raycroft / Golden Retriever (Canis familiaris) with puppy in snow

Mark Raycroft / Russian Wolfhound (Canis familiaris) in snow

Mark Raycroft / Beagle (Canis familiaris) male in snow

Donald M. Jones / American Marten (Martes americana) in snow, western Montana

Mark Raycroft / German Shepherd (Canis familiaris) portrait of adult sitting in snow

Ingo Arndt / Mountain Lion (Puma concolor) watching photographer, Ingo Arndt, and tracker, Torres del Paine National Park, Patagonia, Chile

Sergey Gorshkov / Siberian Tiger (Panthera tigris altaica) in winter, Land of the Leopard National Park, Russian Far East, Russia

Ingo Arndt / Muskox (Ovibos moschatus) herd in winter, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bulls fighting in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) herd huddling in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) group in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) hair on snow, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) herd in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bulls fighting in snow, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) herd after snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bull in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) mother and calf nuzzling in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) mother and calf nuzzling in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bull in winter, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bull in winter, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) herd in winter, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) herd in snowstorm, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bull and female in snow, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) mother and calf in snow, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bull in snow, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bull in snow, Dovre-Sunndalsfjella National Park, Norway

Ingo Arndt / Muskox (Ovibos moschatus) bull in winter, Dovre-Sunndalsfjella National Park, Norway