Realizing that his own life depends on the life of the game, no true trapper will destroy wild creatures when the mothers are caring for their young. Besides, furs are not at their prime when birch-bark is peeled, and the trapper notes the place, so that he may come back when the fall hunt begins. Beaver kittens stay under the parental roof for three years, but at the end of the first summer are amply able to look after their own skins. Free from nursery duties, the old ones can now use all the ingenuity and craft which nature gave them for self-protection. When cold weather comes the beaver is fair game to the trapper. It is wit against wit. To be sure, the man has superior strength, a gun, and a treacherous thing called a trap. But his eyes are not equal to the beaver's nose. And he hasn't that familiarity with the woods to enable him to pursue, which the beaver has to enable it to escape. And he can't swim long enough under water to throw enemies off the scent, the way the beaver does. Now, as he paddles along the network of streams which interlace Northern forests, he will hardly be likely to stumble on the beaver-dam of last summer. Beavers do not build their houses, where passers-by will stumble upon them. But all the streams have been swollen by fall rains; and the trapper notices the markings on every chip and pole floating down the full current. A chip swirls past white and fresh cut. He knows that the rains have floated it over the beaver-dam. Beavers never cut below their houses, but always above, so that the current will carry the poles down-stream to the dam. Leaving his canoe-load behind, the trapper guardedly advances within sight of the dam. If any old beaver sentinel be swimming about, he quickly scents the man-smell, upends and dives with a spanking blow of his trowel tail on the water, which heliographs danger to the whole community. He swims with his webbed hind feet, the little fore paws being used as carriers or hanging limply, the flat tail acting the faintest bit in the world like a rudder; but that is a mooted question. The only definitely ascertained function of that bat-shaped appendage is to telegraph danger to comrades. The beaver neither carries things on his tail, nor plasters houses with it; for the simple reason that the joints of his caudal appurtenance admit of only slight sidelong wigglings and a forward sweep between his hind legs, as if he might use it as a tray for food while he sat back spooning up mouthfuls with his fore paws.