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CASTORID.E. MAMMALIA. CASTORID.E. 



it from freezing to the bottom. The beavers that 

 build their houses in small rivers and creeks, in which 

 water is liable to be drained off when the back supplies 

 are dried up by the frost, are wonderfully taught by 

 instinct to provide against that evil by making a dam 

 quite across the river, at a convenient distance from 

 their houses. The beaver dams differ in shape accord- 

 ing to the nature of the place in which they are built. 

 If the water in the river or creek have but little motion, 

 the dam is almost straight ; but when the current is 

 more rapid, it is always made with a considerable 

 curve, convex towards the stream. The materials 

 made use of are driftwood, green willows, birch, and 

 poplars, if they can be got; also, mud and stones 

 intermixed in such a manner as must evidently con- 

 tribute to the strength of the dam; but there is no 

 other order or method observed in the dams, except 

 that of the work being carried on with a regular sweep, 

 and all the parts being made of equal strength. In 

 places which have been long frequented by beavers 

 undisturbed, their dams by frequent repairing become 

 a solid bank, capable of resisting a strong force both of 

 water and ice ; and as the willow, poplar, and birch 

 generally take root and shoot up, they by degrees form 

 a regular kind of planted hedge, which I have seen in 

 some places so tall that birds have built then- nests 

 among the branches. The beaver houses are built of 

 the same materials as their dams, and are always pro- 

 portioned in size to the number of inhabitants, which 

 seldom exceeds four old and six or eight young ones ; 

 though by chance I have seen above double that num- 

 ber. Instead of order or regulation being observed hi 

 rearing their houses, they are of much ruder structure 

 than their dams ; for, notwithstanding the sagacity of 

 these animals, it has never been observed that they 

 aim at any other convenience in their houses than to 

 have a diy place to lie on ; and there they usually eat 

 their victuals, which they occasionally take out of the 

 water. It frequently happens that some of the large 

 houses are found to have one or more partitions, if they 

 deserve that appellation ; but it is no more than a part 

 of the main building, left by the sagacity of the beaver 

 to support the roof. On such occasions it is common 

 for those different apartments, as some are pleased to 

 call them, to have no communication with each other 

 but by water; so that, in fact, they may be called 

 double or treble houses, rather than different apart- 

 ments of the same house. I have seen a large beaver 

 house built in a small island, that had near a dozen 

 apartments under one roof ; and, two or three of these 

 only excepted, none of them had any communication 

 with each other but by water. As there were beavers 

 enough to inhabit each apartment, it is more probable 

 that each family knew their own, and always entered 

 at their own doors, without any further connection 

 with then- neighbours than a friendly intercourse, and 

 to join their united labours in erecting then* separate 

 habitations, and building then" dams where required. 

 Travellers who assert that the beavers have two doors 

 to their houses, one on the land side and the other 

 next the water, seem to be less acquainted with these 

 animals than those who assign to them an elegant suite 

 of apartments. Such a construction would render 



then- houses of no use, either to protect them from 

 their enemies or guard them against the extreme cold 

 of winter. So far are the beavers from driving stakes 

 into the ground when building their houses, that they 

 lay most of the wood crossways and nearly horizontal, 

 and without any other order than that of leaving a 

 hollow or cavity in the middle. When any unneces- 

 sary branches project inward they cut them off with i 

 then- teeth, and throw them in among the rest to i 

 prevent the mud from falling through the roof. It is a 

 mistaken notion that the wood-work is first completed 

 and then plastered ; for the whole of their houses, as 

 well as their dams, are from the foundation one mass of 

 mud and wood mixed with stones, if they can be pro- 

 cured. The mud is always taken from the edge of the 

 bank, or the bottom of the creek or pond, near the door 

 of the house ; and though their fore-paws are small, 

 yet it is held so close up between them under their 

 throat that they carry both mud and stones, while they 

 always drag the wood with then- teeth. All then- 

 work is executed in the night ; and they are so expe- 

 ditious that in the course of one night I have known 

 them to have collected as much mud as amounted to 

 some thousands of their little handfuls. It is a great 

 piece of policy in these animals to cover the outside of 

 then- houses every fall with fresh mud, and as late as 

 possible in the autumn, even when the frost becomes 

 pretty severe; as by this means it soon freezes as hard 

 as a stone, and prevents their common enemy, the 

 wolverene, from disturbing them during the winter. 

 And as they are frequently seen to walk over them, 

 and sometimes to give a flap with then- tail, particu- 

 larly when plunging into the water, this has, without 

 doubt, given rise to the vulgar opinion that they used 

 then" tails as a trowel with which they plaster their 

 houses ; whereas that flapping of the tail is no more 

 than a custom which they always preserve even when 

 they become tame and domestic, and more particularly 

 so when they are startled. Then- food consists of a 

 large root, something resembling a cabbage stalk, 

 which grows at the bottom of the lakes and rivers 

 (the plant being, according to Sir John Richardson, 

 the yellow water lily, Nuphar luteum). They also 

 eat the bark of trees, particularly those of the poplar, 

 birch, and willow ; but, the ice preventing them from 

 getting to the land in the winter, they have not any 

 barks to feed on during that season, except that of 

 such sticks as they cut down in summer, and throw 

 into the water opposite the doors of their houses; 

 and as they generally eat a great deal, the roots above 

 mentioned constitute a principal part of their food 

 during the winter. In summer they vary their diet by 

 eating various kinds of herbage, and such berries as ' 

 grow near their haunts during that season. When the 

 ice breaks up in the spring the Beavers always leave 

 their houses, and rove about until little before the fall 

 of the leaf, when they return again to their old habita- 

 tions, and lay in their winter stock of wood. They 

 seldom begin to repair the houses till the frost com- 

 mences, and never finish the outer coat till the cold is 

 pretty severe, as hath been already mentioned. When 

 they erect a new habitation they begin felling the 

 wood early in summer, but seldom begin to build until 



