Beaver

Beaver, the popular name of any individual of the genus Castor, which constitutes a family (Castoridae) of the Sciuromorpha or Squirrel-shaped division of simple-toothed Rodents. Authorities differ as to the number of species in the genus; some hold that there are two - Castor fiber, the European, and C. canadensis, the American Beaver; others are of opinion that the differences between the two forms "are sufficiently striking to justify us in regarding them as varieties of one and the same species;" and there are yet other systematists who believe that these differences are not sufficient to warrant the classing of the American Beaver even as a variety. With the exception of the Capybara (q.v.) the Beaver is the largest living rodent. An adult male is somewhat less than a foot in height; the head and body are about 30 in. long, and the tail, which is nearly oval and flattened horizontally, some 10 in. more. The body is stout and massive, the back arched, the head large, the neck short and thick, the muffle naked, ears and tail scaly, the former capable of being folded so as almost to close the passage to the internal ear, the eyes small and furnished with a nictitating membrane, and the nostrils can be closed at will. The general colour of the fur is reddish-brown on the upper surface, lighter and greyish below. The hue varies considerably in different individuals and becomes darker in high latitudes. Numerous instances of black, pied, and albino forms are recorded, and these are noted in some books as distinct varieties. The hind feet are webbed, and all the digits armed with claws; the second toe of the hind feet is usually furnished with a double claw, the supplementary one being under the other. On the right of the opening of the intestinal tube into the stomach there is a large glandular mass, and the anal and urethro-genital orifices open into a common passage. The skull is massive, and there is a distinct sagittal crest for the attachment of the strong muscles which move the lower jaw. There are four molars and one incisor on each side in each jaw, making twenty teeth in all. The incisors, which are of deep orange-red colour, spring from persistent pulps, and are admirably adapted for cutting instruments. Indeed, according to Sir John Richardson, the North American Indians used them to cut bone and to fashion their horn-tipped spears till the introduction of the English file gave the Red man a better tool. The molars are nearly similar in size and structure, but the first is the largest; in the upper molars there are three folds of the enamel on the outer, and one fold on the inner surface, and similar folds, but in reverse order, on the lower molars.

At one time the beaver was plentifully distributed over the northern parts of both hemispheres. Remains have been found in the Fens, and it is said that Beverley owes its name and arms to the fact that beavers once abounded in the neighbouring river. There is historical evidence that they were formerly found in Wales and Scotland, though in the former they were confined to the river Teify in the twelfth century, but they appear to have lived on in Scotland for some 300 years longer. At present there is a protected colony in Bute, and there are some few individuals living under similar conditions in France and Germany. Though the beaver was once plentiful in Scandinavia, it is either extinct there or rapidly becoming so, and it is only in Poland and Russia that the animal can be found under natural conditions in Europe. In Asia it is fairly abundant in Siberia, and in the rivers which flow into the Caspian Sea. In North America, where the beaver formerly ranged over the whole continent from Labrador to North Mexico, it is still fairly abundant in the wilder portions of the western territories. Beavers are aquatic animals, and their dwellings are always close to, or in the neighbourhood of water. They are excellent swimmers, using only the hind feet for this purpose, the fore feet being employed, like hands, in carrying and building operations, and in conveying food to the mouth. They are mostly nocturnal, rarely venturing abroad by day, and live in families or colonies, in a common dwelling in the construction and maintenance of which all are expected to take part. Those animals which neglect to do so are driven away, and live solitarily in burrows of their own, and are generally known as "terriers," and sometimes from their sex, for they are always males, as "old bachelors." Beavers feed mainly on the bark of trees, supplementing this diet by the roots of the common water lily (Nuphar lutea); but when they journey inland, as they do in the warm season, they live on roots, fruit, and corn.

Beavers are excellent wood-cutters. "When the beaver cuts down a tree it gnaws it all round, cutting it, however, somewhat higher on the one side than the other, by which the direction of its fall is determined. The stump is conical, and of such a height as a beaver sitting on his hindquarters could make. The largest tree I observed cut down by them was about the thickness of a man's thigh (that is six or seven inches in diameter), but Mr. Graham says he has seen them cut down a tree which was ten inches in diameter." (Sir J. Richardson.) Another writer, speaking of the destruction of trees by beavers, says, "the timber was entirely penetrated for a space of three acres on the front of the river, and one in depth, and great part of it removed, though some of the trees were as thick as the body of a man." In the enclosure appropriated to the beavers at the Zoological Gardens, Regent's Park, the visitor may see proof of the skill of these animals in felling trees with no other tools than their incisor teeth.

The beaver is hunted for its fur, which was formerly much used for making hats, and to a less extent for gloves. It is now chiefly employed for ladies' capes and for trimming. From the earliest times, too, these animals have been taken for the sake of the castorenm (q.v.), secreted by glands in the groin of the male. Wonderful tales have come down to us from Greek and Roman days, as to how, when hard pressed by the hunter, the animal would bite off these glands - then erroneously supposed to be sexual organs - and escape while his pursuer stopped to pick them up. Another version is to the effect that the beaver would lie placidly on his back when the hunter approached, that he might obtain what he wanted without trouble, and so be induced to spare the life of his victim. The flesh of the beaver is sometimes eaten, and is said to resemble pork in flavour; the tail is considered a luxury by trappers. In the scale of intelligence the beaver stands high, as is shown by its dwellings. The best authority on this subject is Mr. Lewis H. Morgan (The American Beaver and his Works). According to this writer the simplest form of beaver-dwelling is a burrow, differing little from that of other rodents except in the fact that it opens under the water. He supposes that a breach of such a burrow at the upper end, if repaired with sticks and earth, would suggest the beaver lodge - an oven-shaped building of sticks with grass interwoven and plastered with mud - though it must be borne in mind that the animal does not use his tail as a trowel - and repaired or added to when necessary. Of these lodges Mr. Lewis enumerates three kinds, which differ principally in the situations in which they are built - on small islands, in ponds or dams, on the banks of a lake or stream, or shelving shores with a large part of the dwelling built out into the water. But all beavers are not such accomplished builders; in some there would appear to have been degeneration in this respect, or the habit has never been developed. In Mr. Lewis's book will also be found interesting details as to beaver dams, by which these animals keep the water of variable streams up to the necessary height, and the canals by which they transport timber which they cannot roll. The beaver appears first in the Miocene of N. America, and is found in the Pleistocene of Europe. An allied form occurs in the Pliocene of the Auvergne.