This very large, dark brown rodent has a black, scaly tail which is horizontally flattened and paddle shaped and used as a rudder while swimming , as a sturdy support on land and for balance when the beaver carries heavy tree branches or building materials in its front paws. The back feet are large, webbed and black; the eyes and ears small; incisors are very large and chestnut coloured. Average weight is 45-60 pounds but they have been recorded at up to 110 pounds.
Beavers are known for their natural trait of building dams on rivers and streams, and building their homes (known as “lodges”) in the resulting pond. Beavers also build canals to float build materials that are difficult to haul over land. They use powerful front teeth to cut trees and other plants that they use both for building and for food. In the absence of existing ponds, beavers must construct dams before building their lodges. First they place vertical poles, then fill between the poles with a crisscross of horizontally placed branches. They fill in the gaps between the branches with a combination of weeds and mud until the dam impounds sufficient water to surround the lodge.
Beavers’ ability to change the landscape is second only to humans. But that is just one reason why we find the flat-tailed species fascinating. Adults may weigh over 40 pounds, and beavers mate for life during their third year. Both parents care for the kits (usually one to four) that are born in the spring. The young normally stay with their parents for two years, and yearlings act as babysitters for the new litter. While some beaver behavior is instinctive, they also learn by imitation and from experience. Dr. Donald Griffin, the father of animal cognition, has said, “When we think of the kinds of animal behavior that suggest conscious thinking, the beaver comes naturally to mind.”
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