THE BEAVER AS A BUILDER 



By CHARLES A. BRAMBLE 



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OME wonderful 

 yarns have been 

 spun about the bea- 

 ver. A great many 

 are pure fiction, yet 

 having seen a good 

 deal of the animal 

 in the undisturbed 

 solitudes where it 

 is at home, I con- 

 fess to a profound 

 admiration for i t s 

 intelligence. 



I do not think 

 that we can credit some of the things 

 the beaver does to pure instinct. 

 Its actions often seem to be the 

 result of thoughtful deliberation. The 

 beaver sometimes selects a stream in 

 which to build that is shallow, but 

 when it does so you will invariably find 

 that, a short distance below the spot 

 where the house is to be built, there is 

 a possibility of damming the stream, 

 so as to make a pond, having about 

 six feet of water just where the house 

 is to stand. The house is built first 

 of sticks and branches plastered over 

 with mud, making a beehive-shaped 

 structure. The entrance is at a point 

 that will eventually be several feet 

 under the water. After sufficient ma- 

 terial has been gathered for the house, 

 the beaver gnaws out a passageway 

 into it, sloping upward to a circular 

 chamber, which is just about water 

 level, from which leads another pas- 

 sageway into the living room, still! 

 higher. 



The house having been completed, the 

 beaver or rather the beavers, for 

 several, of course, unite their forces, 

 start work upon the dam. When the 

 stream is at all rapid I found that the 

 willow and birch branches were laid 

 with their sharp butts down stream, and 



the twigs pointing up stream. Upon 

 the butts the beaver places quite heavy 

 stones, showing a wonderful apprecia- 

 tion of the mechanical benefit to be de- 

 rived by enlisting the power of the 

 running water to force the butts into 

 the mud and gravel, or, if you prefer, 

 a still more wonderful instinct. Of . 

 course, if a flood came before the dam 

 was finished, it would be carried away, 

 and the animals would have to start over 

 again., something they would lose little 

 time in doing, as their industry and per- 

 severance are proverbial. The tendency 

 of the sharp pointed butt with a heavy 

 weight upon it some little distance up 

 stream, is to penetrate more deeply into 

 the mud as the pressure of water upon 

 the upper branches increases. 



Layer upon layer of boughs are 

 placed, one upon the other, large 

 stones being freely distributed, until, 

 at length, the dam has reached such a 

 height that there will be at least six 

 feet of water at the house. The top of 

 the dam is always thickly covered with 

 mud well plastered down by the 

 beavers. It has been said that the 

 crown of the dam always curves up 

 stream. This is not the case, though 

 there is often a bend in it, sometimes 

 almost at right angles, to take advan- 

 tage of the support of some boulder 

 occupying the bed. of the stream, and 

 when this is the case the sections of the 

 dam leading into the boulder, always 

 run up stream. 



The habits of the beaver render it ab- 

 solutely vital that it shall have a free 

 exit to the water at all times. This is 

 the object of the dam. By providing a 

 pond that will never freeze to within 

 three feet of the bottom, the beaver can 

 always get out of its house to escape 

 from an enemy, or to bring in fresh sup- 

 plies. Their principal food is the bark 



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