Chukotkan reindeer, as a result of domestication, have varied pelt combinations of brown, grey, black and white in the same herd. Evolution and Range Caribou live in tundra and boreal forest regions of both Eurasia and North America, on Greenland and on large northern islands. Within Beringia, they occupy eastern Yakutia, the Anadyr highlands and much of western Alaska, but are absent on most of the Chukotka and Seward peninsulas, where they have been supplanted by reindeer. During the great Ice Age caribou were members of the remarkable array of large mammals inhabiting Beringia. In spring pregnant cows lead the migration to the calving grounds, where each will give birth to a single calf.
Newborns can walk within an hour and in a few days they can outrun a person.
In mid-summer the harassment of mosquitoes and flies can drive the animals to windy coastal areas or old snow patches for relief. In late August or early September the herd begins to drift toward its winter range. Mating occurs enroute during late September and October. Caribou are well adapted to winter conditions. To cope with scarcities and hardships they reduce food intake and lower their metabolic rate.