Wild reindeer are also known as caribou and using both words is correct for this mammal.  Even though the reindeer herds in Canada include thousands of animals, the numbers all over the world are going down due to climate change and loss of habitat.

Many reindeer herds are in the far north. They are suited to very cold weather because their noses feature a specialized type of bone that allows cold air to be warmed before it passes into the lungs, and warm air coming back out is captured for a longer time before the animal breathes it out.  The hooves on caribou change with the seasons, so in summer they are soft to give good traction and in winter they are hard and sharp to cut through ice and snow. 

Amazingly, it is believed that caribou can see ultraviolet light -- they are the only mammals to have this ability!  This can really help them in the Arctic, because signs of predators that would normally blend into the snow can be seen in UV light. 

What predators do they have? Even though reindeer are pretty large animals, there are actually quite a few!  Calves (babies) are the most at risk with the biggest calf predator being the golden eagle. These gigantic birds can carry off a calf from above!  Wolverine, brown bears and polar bears eat reindeer, as do grey wolves.  Reindeer are also big targets for mosquitoes and black flies and these pests can actually leave an animal so weak that it becomes easy prey for the others!

Caribou themselves are ruminants, meaning they eat mostly vegetable matter such as moss and grass and create cud from it and chew it again.  If vegetation is low, they have also been known to eat lemmings, fish and even bird eggs.

When a female reindeer is going to have a calf, it is born after 7 months usually in May or June. In many herds, all the babies are born within two weeks of each other. This may actually protect some of the babies from predators because there are so many all at once. 

Travelling up to 50 kilometres every day during their migration, caribou move to better feeding grounds in the winter and calving grounds for the spring. These animals are also excellent swimmers and will swim across large lakes or rivers if they have to.

Used for food in many cultures, the amazing reindeer is an important animal to many people all over the world.  Now you know some of the things that make reindeer unique!