The Ladies of Santa’s Team

 

 Despite what the holiday TV specials; like Rudolph the Red-nosed Reindeer, lead us to believe, the reindeer that pull Santa’s sleigh are female. You see, reindeer are members of the Cervidae or deer family which also includes: deer, moose and elk. Like the other members of the family the male reindeer grow antlers; but, unlike the rest of the Cervids so do the female reindeer. Since they are antlers, not horns, that means that they are shed and re-grown each year. Male reindeer shed their antlers in November at the end of the breeding season, while the females will keep their antlers through winter until early spring. So, since Santa flies at the end of December, Santa’s reindeer team must be female.

Rangifer tarandus is the scientific name for reindeer or caribou. Some people will use the names interchangeably, while others will say that the animals found in Alaska, Canada and Greenland are caribou, and those that live in northern Asia and Europe are reindeer. And then there are another group of people that say that the name reindeer refers to the domesticated (raised or tended by humans or Santa’s elves) herds of northern Scandinavia and Russia and that caribou are the wild animals in North America. Whatever name you want to use is fine, but what you need to know is that these are some pretty cool animals, that are designed to live in some pretty harsh environments.

Let’s start with a general overall description, since once again if you watch the holiday specials on TV, they will have you believe that reindeer are thin variations based on the more familiar white-tailed deer. Reindeer are rather stout animals with long legs. They have dense chocolate brown fur with a white neck and flank (that’s the last part of the animal to leave the roof).  The fur grows in two layers. A curly, dense under layer for warmth and the hollow guard hairs that help trap warm air near the body. The hollow hairs also float and this helps give the large animals buoyancy when they have to swim, which they do very well. The hair is such an efficient insulator that snow landing on the reindeer’s back will not melt. This efficiency can actually cause them to overheat, even in sub-zero temperatures.   

The males tend to be larger (and with 14 sub-species the range in sizes is huge) averaging between three and five feet in height, 5.9 to 6.8 feet in length and weighing from 140 to 530 pounds. The male antlers are also larger and can reach up to 55 inches in length and may have as many as 44 points. 

Caribou have feet that are designed for life on the tundra. They have four “toes” that can spread wide and work like snowshoes by spreading the weight out over the snow. Being able to spread the toes also helps them to paddle when the animal needs to swim. The caribou is one of the few hoofed animals that have hooves that are covered with hair, even on the bottom. The hair between the toes not only provides traction it also helps to prevent snow from building up between the toes. During the summer, when the ground in the tundra can be soggy and slippery the foot pads will swell and the foot becomes spongey, giving caribou traction on the slick terrain. As winter approaches the foot pad shrinks, exposing the sharp edges of the hoof. These sharp edges help cut into the icy ground giving them a more secure footing. The shrinking of the foot pad also forms a hollow on the bottom of the foot that they can use like a scoop to dig through the snow to get to the lichens.

Reindeer are one of the few large animals that can metabolize and actually survive on lichens. During the warmer months the animals feed on mosses, ferns, mushrooms and other tundra plants, but during the colder winter months, lichens are what is available. Reindeer can eat between 8 and 15 pounds of lichens a day, but since lichen have no proteins the reindeer will still lose weight.

Rudolph may have the only known nose that actually glows red, but reindeer have some serious cold weather noses. They are the only member of the Cervidae family that has hair completely covering the nose. That seems to come in very handy when pushing snow aside to get to the lichens. Reindeer also have increased number of blood vessels in the nose that helps to circulate warm blood through the nose and heat up the arctic air that they are breathing in.  

Living in habitat that has such extreme differences in day length and available light, the caribou or reindeer have eyes that change with the season. The tapetum is a reflective membrane (which is what causes “eye shine” in many animals) located behind the iris that changes from golden in the summer to blue in the winter. When the tapetum changes color it reflects different wavelengths of light. In the summer when there is 24 hours of light the golden color pushes most of the light back out of the eye. In the never-ending darkness of winter, the dark blue scatters the light inside the eye where it has a better chance of being absorbed by the light sensitive cells within the eye. Reindeer or caribou are also one of the few large mammals that have ultraviolet (UV) vision. This ability helps the animals as their snow/ ice covered habitat reflects UV light, while predators, urine and lichen all absorb UV light and would strongly stand out against the reflective ground. 

Caribou are social animals living in herds from ten individuals to fifty-thousand, during migration these herds can join other herds to form what is known as a super-herd that can reach numbers of 500,000 animals.

Not all caribou migrate, but those that do can travel some pretty impressive distances. They are considered to have the longest migration of any land mammal traveling up to 3000 miles in a year. Please note that this is not a straight line measurement but includes all travel in a given year; the distance to and from summer to wintering grounds and the wandering they do enroute.

Whether you will be looking for Santa’s reindeer or not, I think most people would agree caribou (or reindeer) are pretty awesome critters.