Castor canadiensis

The beaver is the largest rodent in North America. (It is most similar to, but not most related to the Muskrat.) Made for the water, it has a large chunky body with a waterproof undercoat and layer of fat to help minimize heat loss in freezing conditions. Its specialized tail is broad and flat with large blackish scales that are used to slap the water's surface to alarm other beavers of danger. (The beaver is nature's engineer by building dams that provide habitat for many other plants and animals.)