Learn and Build Your Own
While we sit in our comfortable and heated homes during these cold winter
months all the wild creatures must cope with these winter extremes with
only what Mother Nature has provided them. There are no fireplaces or
extra logs for the fire in their daily routine. So how do they do it?
Some like bears or ground squirrels hibernate and yet others, like many
species of birds, migrate south to much warmer climates. But what of
our most northern caribou herd? How do they survive or adapt to the extremes
of our northern winters?
The most important behavior caribou have adapted for survival
is their annual migration from their summer range along the north coast
to the boreal forests of the Richardson and Ogilvie mountain ranges. This
700 km trip allows the caribou to seek conditions essential for survival.
The summer feeding grounds of the north coast become unpredictable with
intolerable weather and feeding conditions. Caribou have survived over
the centuries by traveling to the more temperate climate of a boreal forest.
While these migrations will not rival that of the bird world, they are
just as vital to their survival. The boreal forests offer favorable snow
conditions that allow the caribou ready access to their favorite winter
food source, lichens, of which they need to eat approximately 3 kilograms
Caribou have compact bodies, small tails and short ears. Because
of this compactness their surface area that is exposed to the cold so
they can keep their body heat in. The caribou's normal body temperature
is set at 105 degrees F. Their circulatory system is uniquely adapted
to northern climate extremes.
Even though their legs are long, the veins and arteries run close together
and the warm blood pumping from the heart keeps the colder blood in the veins
warm. The legs are kept at a safe 50 degrees F. These long legs are well
suited for quick turns on rough ground, for ploughing deep snow, and for
To keep the heat in, caribou have two layers of fur covering their bodies.
They have a fine crinkly under-fur and a thick coat of guard hairs on top.
Guard hairs are hollow like straws. The air trapped inside the hollow hairs
act as insulation to keep in the caribou's body heat.Caribou are excellent
swimmers. The hollow hairs help them to be boyant in the water.
Feet and Hooves
The caribou's large feet have 4 toes.
Two are small and called "dew claws," and two are large. crescent-shaped
toes that support most of their weight. These large concave hooves offer
stable support on wet, soggy ground and on crusty snow. The pads of the
hoof actually changes from a thick, fleshy shape in the summer to become
hard and thin in the winter months. Additional winter protection comes
from the long hair between the "toes" covers the pads so
the animal walks only on the horny rim of the hooves.
Dozens of times a day caribou thrust their
muzzles into the snow to sniff for food or push snow aside to find food.
Caribou muzzles are unique among the deer family in that they are densely
covered with short hairs; even their nostrils are covered with short
hairs. This helps to warm the intensely cold air before it is inhaled
into the lungs.
Sense of Smell
Another adaptation for living in snowy
conditions is the caribou's fantastic sense of smell. Key to their winter
survival is the low-growing lichen. Even under as much as 5 feet of snow,
a lichen plant can be sniffed out by a hungry caribou.
Caribou like other members of the deer family have a four-chambered stomach
and a complex digestive system that allows them to thrive on vegetation (like
lichens, their main winter food source) that may be low in nutrients but
available in large quantities. An important adaptation for winter survival
as winter food sources often do not contain as high a level of nutrients
as do food sources available in the summer. They quite literally digest every
bit of nutrients possible out of the food they eat.
Organizing the Information
Discuss animal adaptations. Use examples such as long necks on giraffes for reaching
high branches of vegetation, or large eyes on owls for hunting in the night.
Brainstorm other examples of animal adaptations. Discuss adaptations of the caribou
for their environment. Use the information above and any other from research.
- Try using an Attribute Chart to
gather all the facts about caribou adaptations
- Make a large class-size Concept
Map to display all the facts
A. "Building" a Caribou
- Break into small groups and brainstorm ways to build a model of a caribou
using materials that symbolize caribou body parts.
- Build your model caribou. Display your group's creation and explain it
to the class.
B. "Drawing" a
- Draw the basic outline of a caribou on a huge piece
- Using your class Attribute Chart or Concept map decide
how you will show the adaptations on your big paper caribou.
- Break up into groups to add color and detail to the
- Write descriptions of each adaptation and put them
onto the caribou drawing.
*Adapted from PROJECT CARIBOU, An Educator's Guide to Wild Caribou of North