Large hoofed animals belonging to the deer family, caribou and reindeer are actually the same species—Rangifer tarandus. There are differences between caribou and reindeer though. Caribou are native to North America, whereas reindeer are native to northern Europe and Asia. Alaska does have some reindeer, however, imported from Siberia in the late 19th and early 20th centuries.
Some people use the term "reindeer" to refer to domesticated work animals, such as those pulling Santa's sleigh, but there are both wild and domestic herds of reindeer. Caribou, on the other hand, are wild-living and long-migrating. Indigenous groups, including the Sami in northern Scandinavia and the Nenet in Russia's Arctic, herd reindeer and use them for their meat. That's also likely why reindeer evolved to be stockier than caribou.
Caribou make one of the world's great large-animal migrations. As summer approaches, they head north along well-trod annual routes. Some herds may travel more than 600 miles to get to their summer grazing grounds. They'll spend the summer months feeding on the abundant grasses and plants of the tundra. An adult caribou can eat 12 pounds of food each day. This is also when they give birth.
When the first snows fall each year, the caribou turn back south. Herds of female caribou, called cows, leave several weeks before the males, which follow with yearling calves from the previous birthing season. The herds spend the winter in more sheltered climes and survive by feeding on lichens.
Caribou are taller and lankier than reindeer, likely because they evolved to make these long migrations.
Hooves and antlers
Caribou, as part of the deer family, have large hooves that are useful tools for life in the harsh northlands. They are big enough to support the animal's bulk on snow and to paddle it efficiently through the water. The hoof's underside is hollowed out like a scoop and used for digging through the snow in search of food. Its sharp edges give the animal good purchase on rocks or ice.
Caribou are the only deer in which male and females both have antlers—though only some females have them. Cows have one calf each year, which can stand after only a few minutes and move on with its mother by the next day.
Caribou are classified as vulnerable to extinction, one step above endangered. Because they're migratory, changes in the landscape, such as the appearance of new fences or other human development on their migration routes, can be especially disruptive. Climate change is also a threat. As the Arctic warms, they become more susceptible to diseases and parasites, which could quickly spread through a herd.