Caribou

Caribou, Also Called Reindeer

Have you ever seen a deer in the woods? Was it a male or a female? If it had antlers, it was male. But with caribou, you can’t tell by the antlers. Both males and females have them. Caribou live in North America, Europe, and Asia. They are the only species of deer that have been domesticated, or tamed, by humans.

Female caribou tend to have smaller antlers than bull male caribou.

Female caribou tend to have smaller antlers than bull male caribou.  The females can weigh up to 300lbs (136kg), while the bull males can be twice that size.

©G. Ellis/GLOBIO.org

The word “caribou” comes from a Native American word for “snow scraper.” In much of Europe, caribou are called reindeer. The word “deer” comes from the German word “tier,” meaning animal. And the word “rein” comes from the Norse word “hrein” meaning deer. So reindeer means “deer deer” in two different languages.

Habitats in the North

Tundra (top) and boreal forest (bottom) landscapes, where caribou live. ©G. Ellis/GLOBIO.org

Caribou live in the northern regions in the tundra and boreal forests in Canada, Scandinavia, and Russia. Almost one million of the three to five million caribou on Earth live in Alaska, part of the United States.



Tundra (top) and boreal forest (bottom) landscapes, where caribou live.  The tundra of Alaska is a very large open space.  The boreal forest, with needleleaf trees dominating the space, is only found in the Northern hemisphere.

Evolution

Caribou have been around for a long time! Fossils of caribou date the species to more than 1.5 million years ago in the Yukon. They even survived the last Ice Age, which lasted from 100,000 to 10,000 years ago. During that time, it was so cold for so long that many other species, such as the woolly mammoth, became extinct. During the Ice Age, the caribou lived on Beringia, the land that once connected Asia and North America. This area remained ice-free.

Adapted for Cold

Caribou are adapted for the cold, snowy winters in the North. They can lower the rate at which their bodies burn calories to save energy. This lets them take in less food, because they need fewer calories to survive. They also shift their foraging range, the area where they look for food, southward in the winter where there is less snow.

Pestered by Pests

The gray wolf is a natural predator of caribou.

The gray wolf is a natural predator of caribou.  Wolves can’t move as fast for as long as healthy caribou, so they will chase the caribou in relays.  Caribou are only free from this predator during calving time.

©G. Ellis/GLOBIO.org

Caribou interact with a number of species in their habitats that are considered pests, including mosquitoes, warble flies, and nose botflies. During the summer, these insects torment the caribou by buzzing in their faces in great swarms. This pestering makes it difficult for the caribou to eat. During these times, caribou are known to gather in groups of 70,000 to move to areas with more wind—just to get away!

Pursued by Predators

Wolves are a natural predator of caribou, particularly in the winter. A pack of wolves may test a herd of caribou by making them run. The caribou that stumble or run slowly may become the prey of wolves. Grizzly bears also prey on caribou. They choose newborn calves or scavenge on caribou killed by wolves. Golden eagles are known to attack newborn calves from above.

Gray and Brown, or Snowy White

Swimming is natural for caribou.

Swimming is natural for caribou.  Their hooves are broad and large, making them good for swimming.  The hairs of caribou are hollow and taper sharply which helps trap heat close to the body and also makes them more buoyant.

© M. Hoshino/Foto Natura/Minden Pictures

Caribou resemble a large mule deer or small elk. Adults can weigh more than 225 kg. Males (bulls) are often twice as large as females (cows). Coloration varies. In general, caribou that are found near the woods are gray and brown, with white on the neck and back. Caribou that are found in the high northern latitudes and spend much of their time in snow have much more white. Coats also change color with the seasons so that caribou can blend into their surroundings.

Take a look at the caribou to learn more about these cold weather creatures.

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©Gerry Ellis/GLOBIO.org

Locking Horns at Breeding Time

Bulls may engage in battle in order to mate with the females in their herd.

Bulls may engage in battle in order to mate with the females in their herd.  These males have very large antlers that they ram into each other. 

© M. Breiter/Foto Natura/Minden Pictures

Caribou begin to breed when they are around two years old. The breeding time is called the rut. It occurs from September through November. Bulls fight for cows by running into each other head first. They paw at one another and try to injure each other. These fights seem vicious, but rarely result in death unless the caribou lock antlers. If their antlers lock together, the animals become stuck together. They cannot graze for food and may starve to death.

Mothers and Their Young

After caribou breed, calves are born around 230 days later. Mothers quickly bond with their calves, who nurse within minutes after birth and walk within the first hour. The cow teaches her calf to recognize her head-bobbing, which is a sign of danger. Calves follow their mothers as they graze.

Caribou can live up to fifteen years, but the average life expectancy is between 4 and 8 years. Cows live longer than bulls. Why? The rut can leave bulls weak or injured, which makes them targets for predators.

Calves nurse exclusively for their first month, after which they begin to graze.

Calves nurse exclusively for their first month, after which they begin to graze. They will continue to nurse occasionally through early fall, when they become independent.

© M. Hoshino/Foto Natura/Minden Pictures

They Dig Plants

Caribou are herbivores. In the summer, they can eat shrubs, moss, and grasses. In the winter, using their sense of smell, they can locate food under the snow, digging holes with their hooves. These holes are called feeding craters. Caribou eat an average of 2-3 kg of vegetation a day!

Much like cattle, caribou chew their cud. This means that they chew and swallow their food, and then bring it up later to chew again. When they chew it a second time, they break it down further so it is easily digested.

Migration

Caribou are known to travel distances greater than any other land mammal.

Caribou are known to travel distances greater than any other land mammal. They can move more than 5,000 kilometers in a year, with extensive migrations in spring and fall.

© M. Hoshino/Foto Natura/Minden Pictures

Caribou migrate seasonally in a herd. This allows caribou to have the protection of a large group from predators. In the fall and winter they migrate to areas with less snow in order to be able to locate food. In summer, they return to more northern regions when the snow has melted. Caribou travel more than any species on Earth, from 19-55 kilometers in a day. The porcupine caribou migrates over an area of more than 250,000 square kilometers.

Important to People

Caribou are important to many native cultures.

Caribou are important to many native cultures.  For thousands of years, Gwich’in Indians have relied upon the Porcupine River Caribou Herd to meet their subsistence needs.

© M. Hoshino/Foto Natura/Minden Pictures

Native peoples have hunted caribou for thousands of years. They have been eaten as well as used for their antlers and hides. Caribou were hunted in much greater numbers with the development of guns and arrival of Europeans. Fur trappers and miners also used the caribou for food and their hides.

More recently, caribou have been affected by snow machines and snowmobiling as well as road building across their migration routes. Caribou in Alaska are considered endangered because of these actions. The Arctic National Wildlife Refuge in Alaska protects the calving grounds for one of the largest caribou herds in North America.

The Arctic National Wildlife Refuge in Alaska protects calving grounds for caribou.

The Arctic National Wildlife Refuge in Alaska protects calving grounds for caribou.  Each spring, pregnant female caribou begin long migrations towards their traditional calving grounds.  Predators tend to be less of a problem on calving grounds, so the young calves are safer.

©G. Ellis/GLOBIO.org