Donald M. Jones / Barren-ground Caribou (Rangifer tarandus groenlandicus) rubbing antlers on sapling to remove velvet, Denali National Park, Alaska

Matthias Breiter / Arctic Fox (Alopex lagopus) group scavenging at Caribou (Rangifer tarandus) skull and antlers, Churchill, Manitoba, Canada

Matthias Breiter / Arctic Fox (Alopex lagopus) pup playing with Caribou (Rangifer tarandus) antler, Churchill, Manitoba, Canada

Michael Quinton / Caribou (Rangifer tarandus) male, Alaska

Sergey Gorshkov / Caribou (Rangifer tarandus) herd on tundra, Wrangel Island, Russia

Sergey Gorshkov / Arctic Fox (Alopex lagopus) chewing on Caribou (Rangifer tarandus) antler, Wrangel Island, Russia

Sergey Gorshkov / Arctic Fox (Alopex lagopus) pups and mother with Caribou (Rangifer tarandus) antler, Wrangel Island, Russia

Sergey Gorshkov / Arctic Fox (Alopex lagopus) pups playing with Caribou (Rangifer tarandus) skull, Wrangel Island, Russia

Donald M. Jones / Woodland Caribou (Rangifer tarandus caribou) bull, northern British Columbia, Canada

Donald M. Jones / Woodland Caribou (Rangifer tarandus caribou) bull, northern British Columbia, Canada

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

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

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

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

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

Michael Quinton / Caribou (Rangifer tarandus) jumping over barrier onto highway during migration, Slana River, Alaska

Michael Quinton / Caribou (Rangifer tarandus) herd walking, Alaska

Michael Quinton / Caribou (Rangifer tarandus) herd migrating across Tok Cut-Off highway, Alaska

Michael Quinton / Caribou (Rangifer tarandus) herd crossing river, Alaska

Donald M. Jones / American Badger (Taxidea taxus) mother and kits at den, National Bison Range, Moise, Montana

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

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

Donald M. Jones / Caribou (Rangifer tarandus) bull with velvet-covered antlers ovevn fall colored tundra, Denali National Park, Alaska

Donald M. Jones / Caribou (Rangifer tarandus) bull rubbing tree on fall colored tundra, Denali National Park, Alaska

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

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

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

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

Colin Monteath / Caribou (Rangifer tarandus) group running, introduced by whalers in early 1900s, South Georgia Island, Antarctica

Pete Oxford / Mountain Reindeer (Rangifer tarandus tarandus) with Dukha man in taiga, Mongolia

Mark Raycroft / Caribou (Rangifer tarandus) bull in tundra, North America

Mark Raycroft / Caribou (Rangifer tarandus) bull, North America

Mark Raycroft / Caribou (Rangifer tarandus) bull shedding velvet, North America

Mark Raycroft / Caribou (Rangifer tarandus) bulls shedding velvet, North America

Mark Raycroft / Caribou (Rangifer tarandus) bull in fall colored tundra, North America

Ingo Arndt / Caribou (Rangifer tarandus) feeding on tussock grass, Jason Harbor, South Georgia Island

Michael Quinton / Caribou (Rangifer tarandus) mother and calf, Alaska

Michael Quinton / Caribou (Rangifer tarandus) group crossing road, Alaska

Michael Quinton / Caribou (Rangifer tarandus) herd crossing road, Alaska

Michael Quinton / Caribou (Rangifer tarandus) mother and calf, Alaska

Michael Quinton / Caribou (Rangifer tarandus) crossing road, Alaska

Michael Quinton / Caribou (Rangifer tarandus) females and young, Alaska

Michael Quinton / Caribou (Rangifer tarandus) group jumping fence to cross road, Alaska

Jim Brandenburg / Caribou (Rangifer tarandus) at lake, Denali National Park, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) herd, Jason Harbor, South Georgia Island

Ingo Arndt / Caribou (Rangifer tarandus) researcher trying to free animal entangled in wire ropes from old whaling station, Leith Harbor, South Georgia Island

Mark Raycroft / Caribou (Rangifer tarandus) bull in tundra, Alaska

Mark Raycroft / Caribou (Rangifer tarandus) bull in tundra, Alaska

Yva Momatiuk & John Eastcott / Caribou (Rangifer tarandus) bull resting in snow patch to escape insects, Denali National Park, Alaska

Yva Momatiuk & John Eastcott / Caribou (Rangifer tarandus) bull searching for lichen in early spring, Alaska

Jasper Doest / Svalbard Reindeer (Rangifer tarandus platyrhynchus) laying on the tundra in snowfall, Svalbard, Norway

Jasper Doest / Svalbard Reindeer (Rangifer tarandus platyrhynchus) laying on the tundra, Svalbard, Norway

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

Ingo Arndt / Caribou (Rangifer tarandus) herd 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 feeding on lichens, central Alaska

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

Yva Momatiuk & John Eastcott / Caribou (Rangifer tarandus) bulls sparring with antlers during breeding season, Denali National Park, Alaska

Yva Momatiuk & John Eastcott / Caribou (Rangifer tarandus) bull in tundra during breeding season, Denali National Park, Alaska

Yva Momatiuk & John Eastcott / Caribou (Rangifer tarandus) bull on tundra during breeding season, Denali National Park, Alaska

Yva Momatiuk & John Eastcott / Caribou (Rangifer tarandus) bull in fall tundra, Denali National Park, Alaska

Yva Momatiuk & John Eastcott / Caribou (Rangifer tarandus) bull in fall tundra, Denali National Park, Alaska

Yva Momatiuk & John Eastcott / Grizzly Bear (Ursus arctos horribilis) female guarding caribou meat, Richardson Mountains, Dempster Highway, Yukon, Canada

Yva Momatiuk & John Eastcott / Grizzly Bear (Ursus arctos horribilis) female guarding caribou meat, Richardson Mountains, Dempster Highway, Yukon, Canada

Wild Wonders of Europe / Jensen / Barren ground caribou (Rangifer tarandus groenlandicus) carcass, Greenland, August 2009

Ingo Arndt / Caribou (Rangifer tarandus) herd during summer migration, Alaska

Ingo Arndt / Caribou (Rangifer tarandus) herd during summer migration on coastal plains, Alaska

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

Hiroya Minakuchi / Caribou (Rangifer tarandus) bulls molting, South Georgia Island

Hiroya Minakuchi / Caribou (Rangifer tarandus) herd on tundra, South Georgia Island

Michael Quinton / Caribou (Rangifer tarandus) mother and calf crossing road, Slana, Alaska

Michael Quinton / Caribou (Rangifer tarandus) family near road, Slana, Alaska

Michael Quinton / Caribou (Rangifer tarandus) female and calf, Slana, Alaska

Michael Quinton / Caribou (Rangifer tarandus) walking across snowy road, Slana, Alaska

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

Ingo Arndt / Caribou (Rangifer tarandus) bull, Arctic National Wildlife Refuge, Alaska

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

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

Matthias Breiter / Caribou (Rangifer tarandus) male in a field of fireweed, Hudson Bay, Canada

Matthias Breiter / Caribou (Rangifer tarandus) in a field of fireweed, Hudson Bay, Canada

Matthias Breiter / Caribou (Rangifer tarandus) male in a field of fireweed, Hudson Bay, Canada

Jim Brandenburg / Caribou (Rangifer tarandus) male in tundra, Denali National Park, Alaska

Jim Brandenburg / Caribou (Rangifer tarandus) male in tundra, Denali National Park, Alaska

Jim Brandenburg / Caribou (Rangifer tarandus) male, Alaska

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

Donald M. Jones / Caribou (Rangifer tarandus) scratching rear with antlers, 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 on tundra, central Alaska

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

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

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

Jasper Doest / Mountain Avens (Dryas octopetala) flowering in tundra landscape with two Svalbard Reindeer (Rangifer tarandus platyrhynchus), Svalbard, Norway

Jasper Doest / Svalbard Reindeer (Rangifer tarandus platyrhynchus), Svalbard, Norway

Jasper Doest / Svalbard Reindeer (Rangifer tarandus platyrhynchus) group on tundra, Svalbard, Norway