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Beavers
Did you know that beavers are one of the largest rodents in
North America?
These active animals weigh between 44 to 60 pounds. They are about
3-4 feet long.
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Click photo to enlarge
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Where do beavers live?
Beavers live in ponds, lakes, rivers, marshes, and streams
all across the United States. However, they are not found
in Florida and parts of Nevada and California.
What do beavers look like?
Beavers are large brown furry rodents with small eyes, small
rounded ears, large orange teeth, and a large flat, scaly
tail.
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Beavers are very busy.
They spend most of their day searching for food and trees to build
their dams and lodges. It is common to see beaver activity in the
Border Country. Beavers live near water because they have short
legs and do not move well on land. They stay in the water as much
as possible to avoid predators. Their large webbed feet allow them
to swim powerfully through the water.
Why do beavers have such big teeth?
Beavers are related to mice, porcupines, rats, and squirrels. Beavers
have long, sharp teeth known as incisors that are used for gnawing.
These teeth are always growing so it is important for the beavers
to keep them trim by continuously gnawing on trees and branches.
The incisors on beavers can grow as much as 4 feet per year! Beaver
teeth are so strong that they are able to chew through large tree
trunks.
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Click on photo to enlarge
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What do beavers eat?
Beavers love to eat the bark and leaves from the trees that
they fell. Their favorite trees are aspens but they will also
eat birch, alder, willow, and mountain maple. They usually prefer
trees between 2-6 inches in diameter. A busy beaver can chew
through a 5 inch willow tree in 3 minutes! With the leftover
wood they create dams and lodges. A pair of beavers takes down
about 400 trees per year. |
What do beaver families look like?
Beavers seem to keep the same mate for life. They mate between January
and February and the babies or kits are born 4 months later. The
kits weigh about 1 pound each and there may be anywhere from 1 to
8 kits in a litter. The kits stay with their parents for 2 years
until a new litter is born. The kits learn to swim in the lodge
within 30 minutes after they are born. Sometimes when they get tired
their Mom carries them on her back!
Did you know that beavers are the only creatures besides humans
that have such a changing effect on the landscape?
Beavers change the landscape with the dams they build. A dam is
a barrier that stops the flow of water and forms a pond or lake.
These new ponds make it easier for beavers to access trees found
along the shoreline. A mating pair of beavers will usually set out
to find a stream where they can build a dam. They collect logs and
branches in a pile to create the dam and then use grass and mud
to fill in the spaces between the branches. Eventually the water
will pool up on one side of the dam to form a pond. Oftentimes the
dams are strong enough for humans to walk across!
Where do beavers live in the winter?
Beavers live in shelters called lodges. Beavers start working on
their lodges in the fall. Some beavers build in existing lakes while
others build in the newly formed ponds that they made with the dams.
The lodges must be ready by winter to shelter the beavers away from
hungry predators such as wolves, foxes, and otters. Lodges are usually
cone shaped with underwater entrances and are built along the shore.
The beavers build from the inside out using mud, grass, and branches.
Most predators find it too difficult to break through the complex
network of branches and mud so the beavers stay protected. Beavers
that live in rivers do not usually build lodges instead they create
burrows out of the mud along riverbanks.
How do beavers stay warm in the water?
When the lakes and ponds freeze over, beavers swim in the water
underneath the ice. They have thick underfur that keeps them well
insulted and a thick layer of fat under their skin. Beavers also
keep their fur waterproof by rubbing an oily substance on their
fur that is secreted from scent glands.
What makes beavers such good swimmers?
Beavers have large webbed hind legs that act as paddles when they
swim through the water. They have a large flat tail that helps them
steer through the water. They also have clear eyelids that make
it possible for them to open their eyes underwater. These animals
can stay under water for as long as 15 minutes because of their
specially adapted lungs.
Why do beavers have such large tails?
Beavers have wide, hairless, flat tails. Their tails are not only
used for steering but also for balance, warning signals, and fat
storage. When beavers chew on trees they use their tail like a kick
stand to give them support. When a beaver feels threatened by danger
it will slap its tail on the water as a warning to the predator.
Beavers also store fat in their tails for the long, cold winters.
What are some clues of beaver activity to look out for?
Beaver dams and lodges are two easily identifiable clues of beaver
activity. Another clue is to look at the trees along the shoreline
to see any signs of gnawed trees.
Beavers have a dramatic effect on the land. The dams they create
provide new habitat for fish, plants, otters, and other underwater
creatures. The new ponds also provide new water sources for moose
and wolves. The land that dries up near the dams also becomes reforested
because of its rich, fertile soil. Beavers are extremely important
for our forests.
Did you know that beavers are responsible for the exploration
and settlement of Canada and large parts of the northern US?
In the 1500s, European fishermen brought beaver robes purchased
from the Indians back to Spain. The Europeans prized the beaver
fur because of its warmth and its ability to be made into felt hats.
Soon there was a quest in Europe to collect beaver skins from Canada
and the US to sell back home. In the 1600s British merchants traded
with the local Cree Indians for beaver skins. The Indians did all
of the trapping and the Europeans traded them blankets, weapons,
and beads for the skins. The Europeans hired French Canadian farm
boys known as voyageurs to paddle huge birch bark canoes from Montreal
to the Indian villages to collect the beavers. This is the historic
highway that Dave will be following on his Border Country Adventure.
Beaver populations all over North America decreased rapidly until
the 1900s when regulations were set that limited the number trapped.
Great Beaver Links
Sources
Stensaas, M. 1993. Canoe country wildlife: A field guide to the
North Woods and Boundary Waters. Pfiefer-Hamilton, Duluth.
Whitaker, J.O. 1998. National Audubon Society Field Guide to North
American Mammals. Alfred A. Knopf, New York. 
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