If you watch a lot of wildlife documentaries during the holiday season, you may notice that reindeer bear a close resemblance to one of North America’s largest herbivores: the caribou. The distinction between these animals is part cultural and part scientific. And lately, taxonomists have been reconsidering their relationship.
At Your Cervids
Reindeer and caribou are in the family Cervidae, along with white-tailed deer, moose, and elk. Like cows and pigs, cervids are hoofed animals with an even number of toes on each foot. They roam every continent except Australia and Antarctica. Members of this family are largely herbivorous, relying on grasses, shrubs, or other plants for nutrition. Anecdotal evidence claims reindeer have been known to gobble up the occasional lemming as well.
One feature that sets cervids apart is their antlers, comprised of bone as well as nerves, tissues, and blood vessels. In most species, only the males grow them; among reindeer and caribou, both sexes sport antlers. Males’ antlers can measure up to 51 inches long, while females’ are smaller. Caribou and reindeer shed and replace their antlers every year: males start growing a new pair in February and discard in November, and females won’t start developing fresh antlers until May or June.
Reindeer Versus Caribou
Caribou and reindeer belong to the same genus, Rangifer. They’re found across a wide geographic range, including parts of Russia, Mongolia, Norway, Finland, Canada, and Alaska.
For decades, taxonomists identified only one living species in this genus, Rangifer tarandus. Depending on where you lived, you would call this species caribou or reindeer. “In Europe, they are called reindeer. In North America, the animals are called caribou if they are wild and reindeer if they are domesticated,” the FDA explains.
As genomic technology grew more advanced, new analyses of R. tarandus populations in Canada and Europe suggested that the species was split into several distinct subspecies. Individuals of these subspecies bore meaningful physical, behavioral, and geographic differences.
Then, a 2022 study in the journal ZooKeys by Dr. Lee Harding, a Canadian mammologist, argued that these subspecies are so different from each other that they actually deserve their own species designation.
A Species, Divided?
Harding looked at the differences in genetics, anatomy, and behavior among wild Rangifer populations. For example, naturalists have known that “woodland caribou,” a subset of North American caribou, have darker hair than their cousins, “Arctic caribou.” These populations “almost never breed with one another, even where their rutting ranges overlap; or if they do, their calves do not survive,” he wrote in Canadian Geographic.
He suggested splitting the Rangifer genus into five species: Arctic caribou (R. arcticus), woodland caribou (R. caribou), Greenland caribou (R. groenlandicus), Svalbard reindeer (R. platyrhynchus), and Eurasian tundra reindeer (R. tarandus). Not all taxonomic organizations have signed on to the reclassification, however; some still consider these groups subspecies of R. tarandus.
Harding wrote that proper classification of the reindeer/caribou species would aid their conservation. Russia’s overall reindeer population fell by 21 percent between 1990 and 2015, while the last wild caribou population in the contiguous United States became functionally extinct in the late 2010s. Endangered woodland caribou in British Columbia and Alberta are protected under Canada’s Species at Risk Act.