How Do Animals Survive the Cold
Weather of the Tundra?
A Grizzly Bear Mother and Her Cubs
Last night, August 09, it snowed
up in the Mountains.
As the sun rises above the mountains, the
light begins to spread across the tundra and it slowly begins to
warm up. It was very cold last night. From the look of
the ice on our tent, it was below freezing!
It dawns on us that it is August. Back at home people are
swimming in the lake. Here, on the
| tundra, we're shivering as we pack our winter hat, long underwear, gloves, and an insulated
jackets that we slept in, into the top of our backpacks.
We'll need those again tonight.
You must be wondering how the animals that live on the
survive the cool summer nights and the frigid winters.
Today, as we
hike, we'll keep a sharp eye out for animals and explore how they
survive the cold weather.
Long Life Cycle
Down here is a caterpillar many call the Arctic Wooly
Bear. These little caterpillars survive the freezing cold of
summer nights and and the deep freeze of the tundra's winter. Caterpillars in
most areas grow for one summer and then transform into a
butterfly. Here on the tundra, caterpillars only grow a
little during the short, cold summer. It can take them many years,
up to 14 years, to transform into a butterfly. Over the
Over the winter, these
caterpillars freeze solid and thaw out again to resume life once it
is warm enough.
| caterpillars freeze solid and thaw out again to resume
life once it is warm enough. This caterpillar will eventually
transform into a Greenland Sulphur butterfly.
The caribou's body has adapted in
many ways to survive the long, cold winters of Denali.
Each leg has two crescent shaped hooves.
Toughing it Out
There is a caribou. These amazing creatures have
adapted in many ways to survive the long, cold winters of Denali.
First, their hair keeps them very warm. Their long hairs are
hollow and provide very good insulation. Second, each leg has
two crescent shaped hooves. These hooves grow longer in the
Fall. This ensures that the
exposed pad between their hooves stays above the snow. Therefore,
they stay warmer. Third, their long legs are often
submerged in the deep snow. They have had to adapt their circulation system to
prevent their legs from freezing and to keep the cold from spreading
up to their bodies. The arteries and veins in
their legs are very close together. The outward flowing blood
(arteries) warms the inward flowing blood (veins). This allows their
body temperature to remain warm while their
legs are colder.
A Deep Sleep
Wow, that's a grizzly bear. Grizzly bears survive the long
Denali winters by going into a deep sleep. Throughout the
summer, Denali's grizzly bears gorge themselves on
blueberries, roots, and small mammals. They stuff themselves
around the clock to get enough body fat to survive the winter. When
winter approaches they go into their dens that they dig into the
soil or find a natural cave. They
fall into a deep sleep where their temperature,
Grizzly bears survive the long,
Denali winters by going into a deep sleep.
| pulse rates, and
breathing rates become very shallow. The grizzly sleeps so deep that they can
actually have their babies while sleeping and do not wake up during
They go deep down into their
burrows to hibernate during the long, cold winter of Denali.
Look over there. That is an arctic ground squirrel. They
go deep down into their burrows to hibernate during the long, cold
winter of Denali. There burrows are a maze of tunnels and dead
ends. These dead ends actually trap air. The warmth from
the ground heats the air. This warm, trapped air acts as
insulation against the frigid outside temperature. They also line their dens
with grass and other arctic plants to insulate their comfy
home. Then, they hibernate. Their metabolism, heart rate, and
breathing slow down almost to a stop. If their burrows are not
flooded out by water from melting snow, the
| arctic ground squirrel will wake up
in the spring and survive on food they have stored until it is warm
enough to go outdoors.
It is very difficult for animals to survive out here on the
tundra. Just look at all the animals we saw. They have
had to adapt in a variety of ways to withstand the cold. Check out some more of the animals that
live on the tundra to learn about them and how they survive the cold
summer nights and frigid winters.
The Amazing Animals of
So, You Want To Learn More About Alaska's
in a Deep Freeze
This (Hands-On Fun)
Perfect Arctic Animal
Adaptations for Survival