1 THE MIGHTY BEAVER Meet the Mighty Beaver Beavers are amazing They can build structures that are visible from outer space They can turn streams into lakes and change the shape of valleys They can gnaw right through the trunks of trees that are as tall as flag poles And they do all of this with nothing more than their sharp front teeth nimble paws and powerful muscles There are only two kinds of beavers in the world today the North American and the Eurasian Scientists also have fancier names for them They call the North American beaver Castor canadensis and the Eurasian beaver Castor fiber You probably noticed that both names start with the word Castor That tells us that these two species are closely related kind of like cousins Unlike most human cousins Castor canadensis and Castor fiber look nearly identical The only sure way to tell them apart is to examine their DNA the coding instructions for life that every animal and plant carries in its cells DNA analysis shows that the two species of beaver have slightly 55
CASTOR FACT The scientific name for the beaver family is Castoridae Members of this family are called castorids The North American beaver’s historical range Before 1500 Castor canadensis inhabited almost every part of the continent where there was wood and water THE BEAVER DISTRIBUTION MAP HINTERLAND WHO’S WHO CANADIAN WILDLIFE SERVICE ENVIRONMENT CANADA REPRODUCED WITH PERMISSION OF THE MINISTER OF PUBLIC WORKS AND GOVERNMENT SERVICES 2005 Humans have significantly changed the beaver’s world over the past 500 years PHILIPPE HENRY DESIGN PICS GETTY IMAGES different genetic blueprints Nevertheless they do all the same beaverish things like felling trees and building dams This book is mostly about Castor canadensis but a mighty beaver is a mighty beaver no matter where it lives Beaver Geography In ancient times Eurasian beavers were common through out Europe northern Asia and Great Britain Unfortunately humans nearly drove them to extinction By the 1600s there were no more beavers in Britain In Europe and Asia their numbers hit bottom around 1900 At that point only about 1,200 Eurasian beavers remained mostly living in remote parts of Scandinavia Russia and Mongolia Today the Eurasian beaver is making a comeback across much of its range The North American beaver’s homeland is you guessed it North America Long ago beavers populated populated almost every corner of what we now call Canada and the United States plus a sliver of northern Mexico Their domain stretched from the Atlantic coast to the Pacific coast and from just south of the Rio Grande all the way to the northern tree line In a few places it even reached the Arctic Ocean Pretty much the only parts of North America without beavers were those with no trees
or shrubs hot dry deserts alpine areas high in the mountains mountains and the Arctic tundra Most of the Florida peninsula was also off-limits Too many hungry alligators lurk in the swamps there Back then this continent was home to tens of millions of beavers Or maybe hundreds of millions no one knows for sure We do know that Indigenous Peoples had been sharing this continent with beavers for a very long time before Europeans showed up in the late 1400s and that the newcomers rapidly reduced the number of beavers Four-Legged Lumberjacks Beavers are famous for doing two things that no other animals except humans ever do They cut down trees and they build dams These two activities are closely connected because before beavers can start building a dam they have to gather their construction materials Although beavers are sometimes active during the day they usually work the night shift starting near dusk and quitting as the sun rises Their nocturnal habits make it hard to see them in action But if you go for a walk in any beaver neighborhood you’ll find signs of their work Felled trees are hard to miss and their stumps have an unmistakable unmistakable shape they look like the pointy end of a pencil Building isn’t the only thing beavers have in mind when they cut down trees Their first priority is dinner or lunch or breakfast Beavers eat many things but their most important food is cambium the soft nutritious layer of bark that lies between the hard inner wood and the tough outer bark After they’ve eaten the edible parts of a tree including the twigs and leaves they use the trunk and branches to build their dams and lodges Parallel tooth-sized grooves in the wood of these aspen stumps are a sure sign that a beaver cut them down FRANCES BACKHOUSE For beavers the inner bark of a freshly cut tree is delicious and nutritious food FRANCES BACKHOUSE 7
