Reindeer live in the Arctic

Reindeer live on the tundra along the Arctic Circle, and are therefore perfectly adapted to cope with the harsh and long winter. The coat is warm and extremely dense, and it consists of a thick undercoat and long hollow cover hairs. A thick fat layer under the coat acts as additional insulation and energy source during the winter.

Heat exchange in legs and nose

However, the coat and the fat alone cannot protect against the cold that comes from the icy ground. For that, the reindeer has other tricks up its sleeve. In the legs, the blood vessels are so close that the warm blood from inside the body heats the blood that runs back to the heart from the hooves. This means that the hooves can be about 30 degrees colder than the rest of the reindeer. In the same way, the nose of the reindeer utilizes the heat from the blood, by leading every breath of the icy Arctic air through a lot of small labyrinth passages filled with blood vessels. The air is thereby heated before it ends up in the lungs.

Cold air contains very little moisture, and without defense mechanisms, the reindeer would quickly lose plenty of fluid at every single breath. Therefore, the moisture from the hot exhaled air inside the nasal labyrinth passages is condensed. This means that the inhaled air is moistened at the same time as it heats up, and the lungs are thereby protected against both cold and drying out.

Legs of reindeer make clicking noises when they walk

If you listen closely when a reindeer runs or walks, you will be able to hear their legs clicking. This is due to a tendon in their legs that slips over a bone. This sound helps the reindeer stay together in the herd during the dark polar nights and snowstorms where visibility is limited.

Both females and males carry antlers

As the only deer species, both male and female reindeer carry antlers.

Having an antler is a big cost for an animal, which must both use energy to make a new antler every year as well as carry it around. Therefore, it only makes sense for the females to have antlers if it also gives them a clear advantage. In winter, it can be difficult to find food, and if the females did not have antlers themselves, they would have difficulty defending their food against the males. On top of that, the males typically shed the antlers early in the winter after the mating period, while the females keep their antlers until spring. This gives pregnant females in particular an important competitive advantage over the winter.

Does reindeer need lichen?

No, it is an old misconception that the reindeer can only live on lichen. In summer, the reindeer feed on grasses, herbs and flowers, while in the winter it mainly feeds on lichen, as it is the most common food source in the reindeer’s winter area. However, the reindeer can easily live solely on e.g. grass. It just needs to have plenty of time to adjust the rumen to this.

On the island of South Georgia in the southern hemisphere, there is a reindeer population, established by whalers in 1911. Here there is no lichen – only a number of grass species, and yet the reindeer population thrives. This shows something about the reindeer’s adaptability under very different conditions