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. 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
©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. 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. 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.
Locking Horns at Breeding Time
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. 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.
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. 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. 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