Caribou Survival Adaptations:
Article and Activity
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 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 buoyant in the water.
Feet and Hooves
The caribou's large feet have 4 toes.
Two are small and called "dew claws." 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 change from a thick, fleshy shape in the summer to
hard and thin in the winter. Additional winter protection comes
from long hair between the toes that 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. The hairs help 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. Lichen may be low in nutrients but
available in large quantities. They digest every
bit of nutrients possible out of the food they eat. This ability to thrive on winter food sources that do not contain as high a level of nutrients as sources available in the summer is an important adaption for winter survival.
Activity: Build or Draw a Caribou
Discuss animal adaptations. Use examples such as long necks on giraffes for reaching
high branches of vegetation or large eyes on owls for hunting at night.
Brainstorm other examples of animal adaptations. Discuss adaptations of the caribou
for their environment.
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 share it
with 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 paper caribou.
- Divide the class into small groups. Give each group a specific adaptation or body part: feet, stomach, muzzle, legs, and fur. Have each group draw details on the paper
caribou to showcase the adaptation. Have them write descriptions of the adaptation on the drawing.
*Adapted from PROJECT CARIBOU, An Educator's Guide to Wild Caribou of North