The fur consists of two kinds, 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 largest and reddest beavers are those dwelling on the streams of the north ern Pacific Coast, the smallest and darkest those of the Hudson Bay region, while those inhabit ing the southern Alleghanies are reddish brown, and those of the southern Rockies are pale. In consequence of its aquatic and bark-eating habits, the beaver is limited to the neighborhood of streams and ponds in wooded districts, and the northern range of the species is everywhere ter minated by the limits of the forest growth. Its extraordinary powers of gnawing are exerted to cut down trees 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. Dr. Elliott Cones mentions a poplar cut by beavers on the Upper :Missouri, which he found to be feet in circumference at the point of attack; but this was exceptional. This cutting is accomplished by the animals standing upon their hind feet and gnawing in parallel lines across the grain, then wrenching or biting out the chip between, and so steadily deepening the cut. The assertion that they can or do cause trees to fall in any desired direction is not justified by facts. Large trees are usually felled by the united efforts of a fam ily of beavers.
Community Life and .Irehiterlure.—The archi tectural operations and co?Iperative life of these animals are very wonderful, although the state ment, at one time commonly made, that beavers drive stakes into the ground, has no foundation in fact; and some of the other particulars which passed current along with it were equally fabu lous. They dwell normally in colonies along streams, which may have been inhabited for scores of generations, and whose improvements represent the combined labor of thousands of in dividuals past and present. Such a colony begins by the settlement in the spring upon some sluggish, moderately deep woodland stream or pond of a pair of young beaters, who have emi grated thither from some old colony. Their first labor is to dig a burrow in the hank, the entrance to which is at a safe depth beneath the water, and the interior chamber at a safe height above its normal rise. In this burrow they make their home the first year, or perhaps two years; and such burrows, more or less in use and serving as refuges in danger, are common always in heaver settlements. It is essential that a suffi cient depth of water he maintained before the door of this burrow to give clear ingress and egress under the winter's ice, and to afford room for storage of winter provisions; and in most places chosen by the animals this can be arranged only by damming the stream. As the droughts and low water of summer begin, there fore, the beavers seek a place in the stream a little below their residence, where it is narrow, not more than feet deep, and has a firm bot tom, and begin a damn. Gnawing down saplings 10 or 12 feet Tong, they drag and float them to the spot, and sink them lengthwise, side by side, across the current, beginning at the centre of the channel and loading them with stones, sods, and mud, to keep them in plaice. They will handle remarkably large stones for this purpose.
The work is gradually extended until it reaches the bank on each side, and in doing so a convex outline upstream is usually given; but this probably is an accident of the increasing pres su•e of the obstructed current on the progressing wings of the new dam rather than an engineering design, for reverse (or weak) curves are fre quently seen. Such a dam grows constantly by the addition of all sorts of material—not only the logs and sticks from which the bark has been gnawed for food, but others cut for the pur pose, and a constant intermixture of roots and branches with stones, moss, grasses, and mud.
Additions, as well as constant repairs, are made on the upper side, which cones to present a low slope and comparative solidity, while the lower front of the dam is a more abrupt tangle of sticks and branches. The beavers work at the dam only at night, except in an emergency, and each one does what it thinks proper in a quite independent way, though' the result is for common benefit. After many years such dams may he 4 or 5 feet high at the channel, and stretch to the right and left across low ground for 50 yards or more, converting the space above it into a broad, grassy pond. having a network of clear channels. :Morgan describes dams 600 feet long in northern Wiscomfin, with many acres of flooded ground. The water does not flow over the tops these dams. hut percolates through them. though some of them become seemingly solid barriers of earth. "In places," says lIearne, "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 take root and up, they by degrees form a kind of regular planted hedge, which I have seen in some places so tall that birds have built their nests among the branches." A large proportion of the marshy ponds and peat-bogs of the country have had this origin.
Meanwhile, from the first summer onward, the gradually increasing number of beaver fam ilies have built each for itself permanent homes, known from their resemblance to the Algonkian wigwam as 'lodges.' The sites chosen are along the banks of the stream or canal, and several houses may be so close together as to touch, or they may be widely scattered. The larger lodges are, in the interior, about 7 feet in diameter, and between 2 and 3 feet high. with the floor and in ner walls made smooth by gnawing and wear. The entrances are always two, both leading down into the water, and in northerly regions there is no opening into the air—a needful pre caution against the cold of mid-winter, as well as against such insidious foes as weasels and blacksnakes. This structure, like the dam, is formed of branches of treed, matted with mud, grass, moss, and other material. The walls are very thick, and the entire structure not only secures much warmth, but is an efficient protee- ' tion from wolves, wolverines, and other beasts of , prey, especially when solidly frozen in winter. Each family builds, maintains, and occupies its own lodge, the current belief that several families live together arising from the fact that the young beavers usually continue to live with their parents until the third year. Single `bachelors' dwelling remote and alone are occa sionally seen.