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