Caribou running in snow, Alaska

© Michael Quinton/Minden Picture

Merry Christmas, deer friends!. Merry Christmas!

Dashing through the snow on our homepage today, reindeer, or caribou as they are known here in North America, have been synonymous with Christmas for two centuries. American writer Clement Clarke Moore is credited with popularizing them as Santa's helpers in the poem 'A Visit from St. Nicholas,' first published in 1823. And no wonder Santa picked them. With two layers of fur and eyes that adapt to the Arctic's shifting light levels, reindeer are very versatile. You likely won't see them fly, but you might find a herd migrating from tundra to forest in the North Polar Region, North America, Northern Europe, or Siberia. Their hooves can expand or shrink according to ground conditions, keeping their heavy frame stable on soft ground in summer, ice in winter, and steep rooftops at Christmas. If you're celebrating Christmas today, we wish you a merry one.