In the Santa Claus tale, Santa Claus's sleigh is pulled by flying reindeer. These were first named in the 1823 poem "A Visit from St. Nicholas", where they are called Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Dunder, and Blixem. Dunder was later changed to Donder and—in other works—Donner (in German, "thunder"), and Blixem was later changed to Bliksem, then Blitzen (German for "lightning"). Some consider Rudolph as part of the group as well, though he was not part of the original named work referenced previously. Rudolph was added by Robert L. May in 1939 as "Rudolph the Red-Nosed Reindeer".
According to the British comedy panel game QI, Rudolph the Red-Nosed Reindeer and all of Santa's other reindeer must be either female or castrated, because male reindeer lose their antlers during winter.
The reindeer (Rangifer tarandus), also known as the caribou in North America, is a species of deer native to Arctic and Subarctic regions. This includes both resident and migratory populations. While overall widespread and numerous, some of its subspecies are rare and at least one has already gone extinct.
Reindeer vary considerably in color and size. Both sexes grow antlers, though they are typically larger in males. However, there are a few populations in which females lack antlers completely.
Wild reindeer hunting and herding of semi-domesticated reindeer (for meat, hides, antlers, milk and transportation) are important to several Arctic and Subarctic peoples. Even far outside its range, the reindeer is well known due to the myth, probably originating in early 19th century America, in which Santa Claus's sleigh is pulled by flying reindeer, a popular element of Christmas. In Lapland, reindeer pull pulks.