The black tail is horizontally flattened, paddle-shaped and scaly. Large, webbed hind feet are powerful paddles for swimming. The eyes are small and have nictitating membranes, which can be drawn across the eyeball when the beaver is underwater. In addition, the nostrils and ear openings have valves that can be closed at submersion. Finally, structural adaptations in the back of the mouth prevent water getting into the lungs and permit the beaver to gnaw under water and to carry branches while swimming submerged.
Range and Habitat
Beavers inhabit forested regions across Canada and north to the TREELINE, but are infrequent on the prairies. Typically, they occupy slow-flowing streams, where they construct dams of sticks, logs, debris and mud. The beaver is one of the only mammals, other than humans, that can manufacture its own environment. Beavers often build canals for floating logs to build dams. These dams maintain a water supply to protect their lodges, which are built of the same materials as the dams, and have entrances below water level and ramps leading up to living quarters above water.
Dams also provide greater access to the beaver's major food items: leaves, buds, twigs and bark of deciduous and (rarely) coniferous trees. Beavers also eat herbaceous pond vegetation.
Lodges are anchored in the mud of ponds and are made of intricately interlaced branches and stems of trees. Mud and grass are plastered around the outer walls. When the sub-zero temperatures of winter come to freeze a prison of ice around the perimeter of the lodge, it is all but impermeable to predators. While temperatures outside the lodge may range down to -40° C or more, inside the warmth of the animals always keeps the temperature around 8-12° C.
Beavers appear to be strongly territorial, being aggressive towards intruders. To advertise the limits of the territory, mud-scent mounds are placed strategically and castoreum, from the pear-shaped castor glands located in the anal region of both sexes, is regularly applied.
Grasses, SEDGES and wildflowers spring up along pond margins. Aquatic and land insects thrive and provide food for song birds such as song SPARROWS, tree SWALLOWS and cedar WAXWINGS. Mergansers and other species of DUCKS, as well as KINGFISHERS, feed in the shallow waters. Beaver-killed trees provide nesting sites for cavity-nesting birds. Toads, FROGS and newts breed and thrive in the ponds, providing food for HERONS and RACCOONS.
The water and its surroundings attract MINK, MOOSE, MUSKRAT and OTTERS. Abandoned beaver ponds silt in and become grass meadows for DEER, VOLES and other herbivores. Thus, the activities of the beaver serve to increase the BIODIVERSITY of the forested regions of Canada.
Beaver was once considered the most valuable fur, particularly when felt hats made from the underfur were symbols of prestige. The pursuit of BEAVER PELTS from the Maritimes to the Mackenzie Valley led to the exploration of vast regions of what became Canada. When the FUR TRADE first started, it is estimated that there were 10 million beavers living in what is now Canada. By the time the fashion had changed in the mid-1800s, the beaver was almost extinct.
Today thriving populations of beaver occur once again across Canada. Because of the beaver's impact on the development and history of Canada, it is rightly one of Canada's national EMBLEMS, is on the coat of arms for the provinces of Alberta and Saskatchewan (see EMBLEMS, PROVINCIAL AND TERRITORIAL) and has been immortalized in 1000 PLACE NAMES across Canada.
Author R. BOONSTRA
Links to Other Sites
A natural history of the beaver, the largest rodent in North America. Part of the extensive Hinterland Who's Who website.
Symbols of Canada
An illustrated guide to national and provincial symbols of Canada, our national anthem, national and provincial holidays, and more. Click on "Historical Flags of Canada" and then "Posters of Historical Flags of Canada" for additional images. From the Canadian Heritage website.
Canadian Biodiversity Website
A great information source for all budding biologists. Learn about biodiversity theory, natural history, and conservation issues. From McGill’s Redpath Museum.
Top 10 Things Canadians Should Know About Canada
Click on the 101things.ca link to discover the top 10 things people should know about Canada, a list developed from a national survey of what Canadians felt were the 101 people, places, symbols, events and innovations that most define our nation. From the Historica-Dominion Institute.
The natural history of the giant beaver (Castoroides ohioensis,) an animal that roamed across Canada’s landscape 10,000 years ago. From the Yukon Beringia Interpretive Centre.
Glossary: Hudson’s Bay Company
A bilingual glossary of key terms found the Hudson’s Bay Company records. From the website for the Hudson's Bay Company Archives. A PDF file.
Fur Trade Facts
A glossary of terms commonly used in reference to the history of Canada's fur trade. From the website for Alberta's Heritage Community Foundation.
World's Largest Beaver Dam at Home in Canada's Largest National Park
A photo and description of the world's largest Beaver Dam located in Canada's largest national park. From Parks Canada. Wood Buffalo National Park of Canada
Animals as National Symbols
See a listing of animals designated as national symbols for various nations. From the Minnesota Zoo.