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THE BEAVER
Within the realm of nature, the beaver plays an important role, transforming the environment as no other creature on Earth save humans can. Through dam-building, the beaver creates a water habitat for an infinite variety of new creatures.
The Beaver is a semiaquatic mammal noted for the building of dams. They are large rodents; the average adult beaver weighs about 16 kg (about 35 lb), but specimens as heavy as 40 kg (90 lb) have been found. The beavers' prehistoric ancestors weighed between 700 and 800 pounds.
The beaver is usually about 76 cm (about 30 in) long and stands less than 30 cm (12 in) high. The broad, flat, scaly tail is about 25 cm (about 10 in) long and serves as a warning signal when slapped against the water, as a support when the beaver is standing on its hind legs, and as a rudder while swimming. The body is plump, the back arched, the neck thick, the hind feet webbed, and all the digits clawed. The fur is usually reddish-brown above and lighter or grayish below. The skull is massive, with marked ridges for fixing the muscles that work the jaws. The two front teeth on either jaw are like those of other rodents, wearing away more rapidly behind so as to leave a sharp, enameled chisel edge. With these the beaver can cut down large trees. It usually selects trees 5 to 20 cm (2 to 8 in) in diameter, but it can fell trees with diameters as large as 76 cm (30 in).
Excellent swimmers, beavers can swim submerged for a kilometer or more. They can constrict muscles in the ears and nose to prevent water from entering and they also can close their lips behind their incisors to keep water out of the mouth while cutting submerged branches. If not overly active, these creatures can stay under water for at least 15 minutes. When swimming in winter, beavers will make use of air bubbles and air pockets trapped under the ice to extend the time they can stay submerged.
The leaves, twigs and bark of deciduous trees make up the beavers' principal diet, with the aspen tree being a particular favorite when available. Beavers do eat a variety of other vegetation, including floating duckweed, pond lily leaves and roots, bulrushes, bracken fern, tender green grasses, and even algae.
Usually, trees are cut within about 150 feet of the shore. When a tree has been felled, several beavers may participate in removing branches, cutting up limbs and dragging or floating the material to a chosen site to build a lodge or a dam. At the site, branches and limbs are progressively interwoven to produce a solid structure that is then sealed with rocks, mud and grass.
THE BEAVER LODGE
Beavers are social animals. In areas where food is abundant and the locality secluded, the number of families in a beaver community is rather large. The so-called beaver lodge is a unique structure. Three distinct kinds exist, their differences depending on whether they are built on islands, on the banks of ponds, or on the shores of lakes. The island lodge consists of a central chamber, with its floor a little above the level of the water, and with two entrances. One of these, the "wood entrance," is a straight incline rising from the water, opening into the floor of the hut. The other approach, the "beaver entrance," is more abrupt in its descent to the water. The lodge itself is an oven-shaped house of sticks, grass, and moss, woven together and plastered with mud, increasing gradually in size with year after year of repair and elaboration. The room inside may measure 2.4 m (8 ft) wide and up to 1 m (3 ft) high. The floor is carpeted with bark, grass, and wood chips, sometimes with special storerooms adjoining. The pond lodge is built either a short way back from the edge of the bank, or partly hanging over it, with the front wall built up from the bottom of the pond. The lake lodge is built on the shelving shores of lakes.
Dams are used by beavers to widen the area and increase the depth of water around their homes. They are constructed either of sticks and poles or more firmly and solidly of mud, brushwood, and stones. As time goes by the beaver repairs and adds to the dam. Floating material lodges there, and vegetation growing on the top adds its roots to the strength of the dam. Frequently the beaver builds a smaller dam downstream in order to back up some water against the original dam and thus decrease the pressure of water on it from the other side. The dams are about 1.5 m (about 5 ft) high, usually more than 3 m (10 ft) wide at the base, and narrow at the top. Beaver ponds attract fish, ducks, and other aquatic animals. Although the dams cause local flooding, they also help control runoff and reduce flooding downstream. The ponds eventually fill with sediment, and the animals move to a new location. The abandoned area becomes good meadowland. Some dams have been reported to reach more than 1,000 feet in length, creating a lake with numerous lodges.
Although the beaver is a powerful swimmer, it has difficulty dragging over the ground the logs and branches it needs for building and for food. Colonies of beavers therefore often dig canals from the pond to a grove of trees. Such canals are up to 1 m (3 ft) wide and deep and often a few hundred meters long. The timber is then readily floated down the canal toward the pond. Some observations and experiments suggest that dam construction is the beaver's response to the sound of running water.
The beaver has long been of economic and religious importance for some native peoples of North America. For thousands of years, Indians have trapped the beaver for its meat and fur, and saved a space in their religious ceremonies for the creature. With the coming of Europeans to the continent in the 16th and 17th century, beaver fur became an important commodity in the trade between Indians and Whites, and between North America and Europe. Indeed, the fur trade, of which beaver pelts were a major component, provided much of the impetus for early exploration and settlement of the continent.
In 1678 Louis de Buade de Frontenac, then Governor of New France in Canada, suggested the beaver as a suitable emblem for the colony, and proposed it be included in the armorial bearings of Quebec City. In 1690, in commemoration of France's successful defense of Quebec, the "Kebeca Liberata Medal" was struck. A seated woman, representing France, with a beaver at her feet, representing Canada, appeared on the back.
The beaver was included in the armorial bearings of the City of Montréal when it was incorporated as a city in 1833. Sir Sandford Fleming assured the beaver a position as a national symbol when he featured it on the first Canadian postage stamp - the "Three Penny Beaver" of 1851. The beaver attained official status as an emblem of Canada on March 24, 1975.
April 25, 2005
