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

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

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

Bryan and Cherry Alexander / Chukchi girls, with their family's ancestral clan mark painted in reindeer blood on their face, a ritual during the Chukchi 'Festival of the Young Reindeer' during which young reindeer are sacrificed....

Petra Wegner / Mixed Breed puppy, 12 weeks / Pug crossbred, sitting on small sofa with reindeer toy.

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 / Young Sami girl leading Reindeer (Rangifer tarandus) at start of Spring migration. Kautokeino, Norway, 1972.

Wild Wonders of Europe / de la Lez / Young Svalbard reindeer (Fratercula arctica) lying on ground, Svalbard, Norway, July 2008

Wild Wonders of Europe / de la Lez / Young Svalbard reindeer (Rangifer tarandus platyrhynchus) rubbing its head on adults back, Svalbard, Norway, July 2008

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

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

Yva Momatiuk & John Eastcott / Caribou (Rangifer tarandus) young bull in summer tundra, Denali National Park and Preserve, Alaska