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

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

Jami Tarris / Caribou (Rangifer tarandus) entering teepee for food, Khovsgol, Mongolia

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.

Mark Raycroft / Woodland Caribou (Rangifer tarandus caribou) mother nursing calf, Newfoundland, Canada

Mark Raycroft / Woodland Caribou (Rangifer tarandus caribou) male, Newfoundland, Canada

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.

Donald M. Jones / Caribou (Rangifer tarandus) bull in tundra, Denali National Park, Alaska

Ingo Arndt / Svalbard reindeers (Rangifer tarandus platyrhynchus) running in snow, winter, Spitsbergen, Svalbard, Norway, April

Ingo Arndt / Reindeer (Rangifer tarandus) bull, Jason Harbour, South Georgia, February

Pal Hermansen / Herd of domesticated Reindeer (Rangifer tarandus) moving around, Norway, September.

Pal Hermansen / Herd of domesticated Reindeer (Rangifer tarandus) moving around, Norway, September.

Danny Green / Caribou / Reindeer bull (Rangifer tarandus) close-up grazing, Denali National Park, Alaska, USA, September

Pal Hermansen / Domestic reindeer herd (Rangifer tarandus) group close together in enclosure, Oppland, Norway, September 2014.

Sergey Gorshkov / Siberian Tundra Reindeer (Rangifer tarandus sibiricus) herd migrating through snow, Putoransky State Nature Reserve, Putorana Plateau, Siberia, Russia

Donald M. Jones / Barren-ground Caribou (Rangifer tarandus groenlandicus) bull in tundra, central Alaska

Donald M. Jones / Barren-ground Caribou (Rangifer tarandus groenlandicus) bull in tundra, central Alaska

Donald M. Jones / Barren-ground Caribou (Rangifer tarandus groenlandicus) bulls in rainfall, central Alaska

Donald M. Jones / Barren-ground Caribou (Rangifer tarandus groenlandicus) bulls in rainfall, central Alaska

Roland Seitre / Svalbard Reindeer (Rangifer tarandus platyrhynchus) male and females running, Spitsbergen, Svalbard, Norway

Roland Seitre / Svalbard Reindeer (Rangifer tarandus platyrhynchus) pair, Spitsbergen, Svalbard, Norway

Roland Seitre / Svalbard Reindeer (Rangifer tarandus platyrhynchus) male, Spitsbergen, Svalbard, Norway

Loic Poidevin / Reindeer (Rangifer tarandus) calf next to mother's legs, Finland, April.

John MacPherson / Reindeer (Rangifer tarandus) fighting, Cairngorms National Park, Scotland, UK, March.

Hermann Brehm / Reindeer (Rangifer tarandus) in woodland, Sweden, September.

Espen Bergersen / Two Svalbard reindeer (Rangifer tarandus platyrhychus) Svalbard, Norway, April.

Arne Hodalic / Nenet herdsman with Reindeer (Rangifer tarandus) during summer migration, Yamal Peninsula, Russia. May.

Uri Golman / Greenland reindeer (Rangifer tarandus groenlandicus) in velvet, Kangerlussuaq, Greenland, June.

Uri Golman / Forest reindeer, (Rangifer tarandus fennicus) in velvet, Viiksimo, Kuhmo region. Finland, July. Rare subspecies which were nearly extinct in the 19th Century.

Uri Golman / Svalbard reindeer (Rangifer tarandus platyrhynchus) in velvet, resting, Svalbard, Norway, August.

Espen Bergersen / Svalbard reindeer (Rangifer tarandus platyrhynchus) in distance at sunset, Svalbard, Norway. April.

Richard Kirby / Svalbard reindeer (Rangifer tarandus platyrhynchus) mother and calves, Svalbard, Norway, February.

Jenny E. Ross / Svalbard reindeer (Rangifer tarandus platyrhynchus) jumping across a narrow gully, Eidembukta, Spitsbergen, Svalbard, Norway. August.

Espen Bergersen / Svalbard reindeer (Rangifer tarandus platyrhynchus) rear view lying down, resting at sunset, Svalbard, Norway. April.

Mark Hamblin / Reindeer (Rangifer tarandus) adult male, antlers in velvet, walking across upland moor, Cairngorms, Scotland, UK, August.

Staffan Widstrand / Svalbard reindeer (Rangifer tarandus platyrhynchus) with bloody antlers shedding velvet, Spitsbergen, Svalbard, Norway, September

Staffan Widstrand / Two Svalbard reindeer (Rangifer tarandus platyrhynchus) fighting; antlers shedding velvet; Spitsbergen, Svalbard, Norway, September

Peter Cairns / Svalbard reindeer (Rangifer tarandus platyrhynchus) backlit in evening light, Spitsbergen, Svalbard, Norway, August.

Colin Monteath / Caribou (Rangifer tarandus) and Tsataan reindeer herders in winter camp, Hunkher Mountains, northern Mongolia

Ole Jorgen Liodden / Svalbard reindeer (Rangifer tarandus platyrhyncus) feeding at sunset, Spitsbergen, Svalbard, Norway, April.

Mark Raycroft / Caribou (Rangifer tarandus) bull on autumn tundra

Theo Bosboom / Reindeer (Rangifer tarandus) male walking across beach in winter, near Hofn, Iceland, February

Theo Bosboom,Theo Bosboom / Reindeer (Rangifer tarandus) group grazing in the snow, near Hofn, Iceland, February

Igor Shpilenok,Igor Shpilenok / Large male Reindeer (Rangifer tarandus) standing in shallow waters of the Kronotsky lagoon, away from biting insects. Kronotsky Zapovednik Nature Reserve, Kamchatka Peninsula, Russian Far East, July.

Igor Shpilenok,Igor Shpilenok / Portrait of male Reindeer (Rangifer tarandus) with large antlers, in velvet. Kronotsky Zapovednik Nature Reserve, Kamchatka Peninsula, Russian Far East, June.

Michael Quinton / Caribou (Rangifer tarandus) pair running in snow, Alaska

Mark Hamblin / 2020VISION / Reindeer (Rangifer tarandus) on upland plateau, Cairngorms National Park, Scotland, UK, August.

Mark Hamblin / 2020VISION / Reindeer (Rangifer tarandus) on upland plateau, Cairngorms National Park, Scotland, UK, August.

Steven Kazlowski / Caribou (Rangifer tarandus) pair walking at sunset in the arctic, North Slope of Brooks range, Alaska, USA

Erlend Haarberg / Wild Reindeer (Rangifer tarandus) herd, Forollhogna National Park, Sor-Trondelag, Norway, August

Erlend Haarberg / Wild Reindeer (Rangifer tarandus) silhouetted, Forollhogna National Park, Sor-Trondelag, Norway, September

Ole Jorgen Liodden / Svalbard Reindeer (Rangifer tarandus) grazing in midnight sun. Spitsbergen, Svalbard, August.

Ole Jorgen Liodden / Domestic Reindeer (Rangifer tarandus) running in morning light. Norway, December 2010.

Sergey Gorshkov / Caribou /Reindeer (Rangifer tarandus) on hillside, Kamchatka, Far east Russia, September

Sergey Gorshkov / Aerial view of Caribou / Reindeer (Rangifer tarandus) trotting through shallow water, Kamchatka, Far east Russia, August

Bryan and Cherry Alexander / Nenets herder selecting draught Reindeer / Caribou (Rangifer tarandus) from a corral. Yamal, Siberia, Russia, 1993.

Bryan and Cherry Alexander / Driving Reindeer / Caribou (Rangifer tarandus) across tundra at sunset. Khanty Mansiysk, Western Siberia, Russia, 2000.

Bryan and Cherry Alexander / Sun rises behind Reindeer / Caribou skin tents at a Nenets herders' winter camp. Yamal, Siberia, Russia, 1993.- 40 BELOW BOOK

Bryan and Cherry Alexander / Reindeer / Caribou (Rangifer tarandus) at their winter pastures in the mountains near Verkhoyansk. Yakutia, Siberia, Russia, 1999.

Bryan and Cherry Alexander / Khanty herder standing on sled, with Reindeer / Caribou (Rangifer tarandus). Khanty Mansiysk, Western Siberia, Russia, 2000.

Bryan and Cherry Alexander / Dolgan reindeer / caribou herder's balok (wooden hut built on sled runners) with chimney smoking. Taymyr, Northern Siberia, Russia, 2004.

Bryan and Cherry Alexander / Dolgan family of reindeer / caribou herders having meal together inside their balok (moveable hut built on sled runners). Taymyr, Northern Siberia, Russia, 2004.

Bryan and Cherry Alexander / Dolgan reindeer / caribou herder carrying block of ice to be used for drinking water. Taymyr, Northern Siberia, Russia, 2004.

Juan Carlos Munoz / Herd of wild Reindeer (Rangifer tarandus) running past young spruce trees in Taiga woodland, Lappland, Finland, March 2007

Bryan and Cherry Alexander / Aerial view of Caribou / Reindeer (Rangifer tarandus) crossing lake during summer migration. Hudson Bay, Canada, 2004.

Bryan and Cherry Alexander / Aerial view of Caribou / Reindeer (Rangifer tarandus) migrating across the tundra in summer. Hudson Bay, Canada, 2004.

Jack Dykinga / Tributary stream pouring into the Snake River, dawn, Caribou National Forest, Idaho, USA

Ingo Arndt / Caribou (Rangifer tarandus) herd crossing a Kongakut River during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) pair crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) bull crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) mother and calf crossing a river during summer migration, Arctic National Wildlife Refuge, Alaska

Donald M. Jones / Caribou (Rangifer tarandus) bull on tundra, central Alaska

Donald M. Jones / Caribou (Rangifer tarandus) bull on tundra, central Alaska

Donald M. Jones / Caribou (Rangifer tarandus) bull on tundra, central Alaska

Donald M. Jones / Caribou (Rangifer tarandus) bull in velvet, central Alaska

Donald M. Jones / Caribou (Rangifer tarandus) bull in velvet, central Alaska

Donald M. Jones / Caribou (Rangifer tarandus) bull in velvet, central Alaska

Jasper Doest / Caribou (Rangifer tarandus), Abisko, Sweden

Jasper Doest / Caribou (Rangifer tarandus) herd in snowy landscape, Abisko, Sweden

Jasper Doest / Caribou (Rangifer tarandus) in the snow, Abisko, Sweden

Jasper Doest / Caribou (Rangifer tarandus) in snowy landscape, Abisko, Sweden

Jasper Doest / Caribou (Rangifer tarandus) in snowy landscape, Abisko, Sweden

Mark Raycroft / Caribou (Rangifer tarandus) male standing on autumn tundra, Canada

Sergey Gorshkov / Caribou (Rangifer tarandus) mother and calf nuzzling, Kamchatka, Russia

Tom Vezo / Herding Reindeer / Caribou by helicopter {Rangifer tarandus} Nome, Alaska, USA

Jose Schell / Caribou / Reindeer juvenile portrait {Rangifer tarandus} northern Quebec, Canada September

Tom Vezo / Caribou / Reindeer calf {Rangifer tarandus} Newfoundland, Canada

Niall Benvie / Domesticated Reindeer / Caribou (Rangifer tarandus) female in snow, Scotland

Jose Schell / Male Caribou / Reindeer {Rangifer tarandus} northern Quebec, Canada, September