Lakeside Nature Center

Critter Corner -Beaver
(Castor canadensis)



The Beaver is the largest rodent in North America and can grow to a length of four and a half feet.  The eyes of a beaver are protected by a special covering, called a nictitating membrane, that allows the beaver to see extremely well in the water (like a built-in scuba mask).  Beavers can also close their noses and ears when they are busy working underwater.


Beaver food is mainly bark and cambium (the soft growing tissue under the bark of plants); they prefer willow shoots, but they enjoy maple, aspen, poplar, beech and alder.  They also munch on water plants, buds and roots. 


Beaver moms have litters of 3 to 4 young in April, May or June.  At birth, baby beavers are covered with fur, their eyes are open and their teeth are visible. They can already swim at this time but will not leave the safety of the den for a month.  Beaver parents care for and protect their young for about two years and then the young adult beavers leave on their own to start their own families.


Beavers build elaborate homes called lodges. that look like islands in the middle of a body of water.  It’s made of sticks, grass and moss.  The beavers constantly repair the dome, adding material and plastering the whole lodge with mud.  Entrances are underwater; the beaver has to dive under water to get into his house. 


When alarmed a beaver will give a loud slap repeatedly on the water with its broad tail.  If cornered a beaver may use its enormous incisors to deliver a powerful bite but its first instinct is to escape from any threat by a water route.


  • Even though wild beavers don’t eat yams, the beavers rehabilitated by Friends of Lakeside Volunteers love yams – as you can tell from this picture

  • A beaver has furry lips that close BEHIND the large incisor teeth; this is a special adaptation for eating underwater!

  • Beavers have webbed feet to help them swim better.  Their tails act as rudders.

  • The largest beaver ever found in Missouri weighed 115 lbs.

  • Beavers are usually nocturnal but will work during the daytime in the fall when food is gathered in preparation for winter.

  • Beavers build dams to make sure that the water around their houses is deep enough.  The dams help to maintain wetlands, prevent erosion and stop the flow of floodwaters.  As beaver ponds get bigger because the dams hold in water, pond weeds and water lilies start to grow.  When beavers leave their homes, the dams decay and the ponds turn into meadows.

 To learn more about beavers

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(Photo of beaver eating yams by Deb Hilburn; diagram of beaver lodge from Saskatchewan Schools Information Project; all other photos from US Fish and Wildlife Agency)

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