Mammals: Reindeer (Caribou)

Reindeer sometimes travel more than 600 miles (965 kilometers) between summer and winter feeding grounds.

Reindeer or caribou?

Even though no one has actually seen a reindeer fly, this special member of the deer family has a lot to live up to! Reindeer and caribou are classified as the same genus and species—Rangifer tarandus—but caribou are slightly larger, and reindeer are domesticated. “Reindeer” is the European and Asian name for the animal that is used by humans to pull sleds or carry packs, and “caribou” is the name used in the northern parts of North America. Those of us in the United States use “reindeer” when referring to the domesticated animal.

From the top

Antlers are the most memorable characteristic of reindeer. In males, antlers can measure 20 to 51 inches (52 to 130 centimeters), and females’ antlers can reach 9 to 20 inches (23 to 50 centimeters). Unlike horns, antlers fall off and grow back larger every year. While the new antlers grow, the deer is said to be “in velvet,” because skin, blood vessels, and soft fur cover the developing antlers. Males begin to grow antlers in February and females in May. They both finish growing their antlers at the same time and shed or rub off the velvet during September. However, they shed their antlers at different times of the year. A male drops his during November, leaving him without antlers in December, while female reindeer keep their antlers through the winter until their calves are born in May. This fact has led many to believe that, based on the presence of antlers, Rudolph the red-nosed reindeer must have been a female to have those antlers on Christmas Eve!

But what are the antlers for? They are handy weapons against predators, and males use their impressive antlers (which can weigh up to 33 pounds, or 15 kilograms!) to impress the females.

Masters of a cold world

Reindeer are built for staying warm in freezing temperatures. They are covered in hair from their noses to the bottoms of their feet! Having hairy hooves may look funny, but they give reindeer a good grip when walking on frozen ground, ice, mud, or snow. Reindeer have two coat layers: an undercoat of fine, soft wool that stays right next to their skin and a top layer of long, hollow guard hairs. The air trapped inside the guard hairs holds in body heat to keep the animal warm against wind and cold. The hollow hairs also help the reindeer float, allowing it to swim across a river, when needed. The reindeer’s heavy coat is usually a brownish color in warmer weather and whiter when it’s cold.

Another outstanding feature is right under the reindeer’s nose—actually, it IS its nose! Not only does a reindeer have a great sense of smell to find food and avoid danger, that nose also helps it survive! Reindeer have specialized noses that warm incoming cold air before it enters the lungs, and this adaptation gives the animal a super sniffer! Its sense of smell helps the reindeer find food hidden under snow, locate danger, and recognize direction. Reindeer mainly travel into the wind to pick up scents.

At the other end of the body, the reindeer’s hooves also help out. Being broad, flat, and having two toes, the hooves allow the reindeer to walk on soft ground and in snow and also allow it to push water aside when the animal swims!

Reindeer are social animals and are most comfortable when near other reindeer.

The more the merrier

Reindeer love a good crowd. A social species, they form large regional herds of 50,000 to 500,000 animals during the spring. The herds generally follow food sources, traveling south (up to 1,000 miles, or 1,600 kilometers) when food is hard to find in winter. Reindeer are ruminants. When available, they eat mosses, herbs, ferns, grasses, and shoots and leaves of shrubs and trees, especially willow and birch. In winter, they make do with lichen and fungi, scraping the snow away with their hooves. A special enzyme in their stomach breaks down lichen, an energy-rich food. An average adult reindeer eats 9 to 18 pounds of vegetation a day. At the San Diego Zoo, the reindeer are fed alfalfa hay and pellets, and leaf eater biscuits.

Things get a little fuzzy for reindeer when their antlers are covered in fur and skin called “velvet.”

Reindeer games

After males rub the velvet off their antlers, their bodies continue to prepare for the breeding season. Their necks swell, their stomachs draw in, they grow a mane of hair under their neck, and they start to fight with each other, sometimes resulting in death. The winner chooses 5 to 15 females to be in his “harem.” Those that become pregnant leave the herd in the spring and travel to a traditional calving ground. Here, they give birth within a 10-day period of each other, usually in May and June. Newborns are able to follow their mother just one hour after birth and can outrun a human when one day old! A reindeer calf nurses for at least one month and sometimes even until the winter, six months later.

Reindeer in danger

The reindeer is thought to have first been domesticated by humans at least 3,000 years ago (and perhaps as long as 7,000 years ago) in northern Eurasia ( Lapland) and still remains the only deer species to be widely domesticated. They are used as beasts of burden and farmed for milk, meat, and their hides. Currently, there has been concern about how herds will be affected by companies drilling for oil and gas lines, as these activities often block the reindeer’s travel routes.