BEAVER, Castor fiber, a quadruped of the order glires, or rodentia (q.v.), valued for its fur, and for the peculiar substance called castorcum which it yields, and also much noted for its instincts. Some naturalists regard the American B. as distinct from that of Europe and Asia; but the differences observable either in external or anatomical characters are very inconsiderable; and the opinion that a great difference exists in instincts and habits, appears to have been too hastily adopted. If there is only one species of B., it is very widely distributed in the northern regions of the world, reaching in America almost as far S. as the gulf of Mexico. It once existed in the British islands, where, however, it has long been extinct; and it has become rare in Europe, in many parts of which it was once common. It has become rare also in the United States, disappearing before man; but is nowhere so abundant as in that wide region of lakes and rivers which lies to the n. and w. of the settled parts of North America. Considerable numbers of beavers are found on the banks of the Obi and other rivers of Siberia, and in Kamtchatka.
The incisors or cutting teeth of the B. are remarkably strong, and exhibit in the highest degree the distinctive character of the order to which it belongs—the front of hard enamel, which in the B. is of a bright orange color; the back of the tooth formed of a softer substance, more easily worn down, so that a sharp, chisel-like edge is always preserved; the bulbs being also persistent, so that the teeth are continually growing, as by their employment in gnawing wood they are continually being worn away. There are four fiat molar teeth (or grinders) on each side in each jaw. Each foot has five toes: those of the fore-feet are short, and not connected by a web: those of the hind-feet are long, spreading out like the toes of a goose, and webbed to the nails. In accordance with this remarkable peculiarity, the B., in swimming. makes use of the hiud-feet alone, the fore-feet remaining motionless and close to the body. Another character, to which nothing similar appears in any other rodent, is the large, horizontally flattened tail, which, except at the root, is not covered with hair, like the rest of the body, but with scales. The caudal vertebrze, however, do not exhibit a flattened form.
The B. is usually at least 2 ft. in length, from the nose to the root of the tail; the tail is of an oval form, about 10 in in length, fully 3 in. in greatest breadth, and scarcely an inch in thickness. These dimensions are sometimes exceeded. The general form of the animal is thick and clumsy, thickest at the hips, and then narrowing abruptly, so that it seems to taper into the tail. The head is thick and broad, the nose obtuse, the eyes small, the ears short and rounded. The fur con sists of two kinds of hair; the longer hair comparatively coarse, smooth, and glossy; the under coat dense, soft, and silky. The color is generally chestnut, rarely black, spotted, or nearly white.
The 13. is very aquatic in its mode of life, and it seldom wanders far from some lake or river. In consequence of its habits, it is also limited to wooded districts, and the northern range of the species is everywhere terminated by the limits of the wood upon the river-banks.
The food of the B. consists of the bark of trees and shrubs (birch, poplar, willow, etc.), and of the roots of water-lilies (auphar luterun) and other aquatic plants. In summer, it eats also berries, leaves, and various kinds of herbage. There is reason to think that it never, as has been supposed, kills or eats fish. Like some other rodents, it lays up stores of provisions for winter; but these, iu the case of the B.. consist chiefly of bark, or of brandies, and even trunks of trees. Its extraordinary powers. of gnawing
are exerted to cut down trees of several inches in diameter, both for food, and for the construction of those houses and dams which have rendered it so much an object of admiration to mankind. A tree of IS in. in diameter has been found thus cut down by beavers, although smaller ones are usually preferred; and when a tree of this size is cut, the branches only, and not the trunk, are employed in the architectural operations of the animals. These operations are very wonderful, although the. statement, at one time commonly made, that beavers drive into the .ground, has no foundation in fact; and sonic of the other particulars which passed current along with it, were equally fabulous. The houses or lodges of beavers are grouped together near the edge of the water, the mud being scraped away from the front, so that there may be a sufficient depth of water there to allow free egress, even during the most. severe frost. The winter stores of the animals, consisting of piles or heaps of wood, are also always under water, at such a depth that they cannot be locked up in ice. When the depth of water is not sufficient, the beavers construct a dam across the stream, by the side of which the lodge is placed; the dam is sometimes as much as 30 yards in length, convex towards the current, and most convex in the strongest currents, sometimes extending on both sides beyond the natural channel of the stream. The materials of which it is composed are sticks, roots, and branches, with stones, moss, grasses, and mud, strangely com mingled, but in such a manner that the structure becomes absolutely water-tight. Branches of which the bark has been used for food, or taken off for winter provender, are very generally employed for building purposes. In their building, beavers interlace small branches with each other and with the larger; and a B. kept in confinement has been known to manifest this instinct, by interlacing brandies with the bars of its cage, whilst it also tilled the interstices with carrots, and other vegetables, given it for food, nicely bitten to the proper size, and packed in snow, to protect itself from the cold. B. damns are built with the sides inclining towards one another, so that although 10 or 12 ft. wide at bottom, they have a narrow top. The dams and houses arc annually repaired, before winter comes on, the work being performed by night. " In places," says Hearne, "which have been long frequented by beavers undisturbed, their dams, by frequent repairing, become a solid bank, capable of resisting a great force, both of water and ice; and as the willow, poplar, and birch generally lake root and shoot up, they by degrees form a kind of regular planted,liedge, which I have seen in some places so tall that birds have built their nests among 'the branches." A broad ditch is often dug all around the lodge, so deep that it cannot freeze to the bottom. and into it the beavers make the holes by which they go out and bring their food. The larger lodges are in the interior, about 7 ft. in diameter, and between 2 and 3 ft. high. The top is formed of branches of trees, matted with mud, grass, moss. etc. The walls are very thick, and the whole structure not only secures much warmth, but is a sufficient protection from wolves, wolverines, and other beasts of prey. Different apartments have often one common roof, but they have usually no internal communication. The sleeping-places of the animals are around the wall of their lodge, the center being left free; they are formed merely of a little grass or tender bark of trees. A single house seldom contains more than ten or twelve beavers, but many such families are often con gregated in one place. Beavers, both in a wild state and in confinement, are scrupu lously cleanly in their habits.