90 



THE GNAWERS 



teeth. The beaver cuts the tree all around with upward 

 and downward strokes until it resembles an hourglass 

 (Fig. 72). The amount of work thus accomplished can be 

 imagined when it is known that poplars nine feet in cir- 

 cumference have been found cut half through. The logs 

 are used in forming the braces for the dam, and are often 

 very skillfully placed, curving against the torrent. The 



dam proper is 



built of mud, 

 brush, and ref- 

 use of all kinds, 

 which the bea- 

 vers bring and 

 heap up, plac- 

 ing logs of va- 

 rious sizes over 

 it until a per- 

 fect dam is the 

 result. This 

 brings the 

 water up to 

 the required 

 level. The 



Fig. 72.— Beavers at Work felling a Tree. 



houses are two-storied. The lower story is in the water, 

 and is used as a sort of storeroom; the other is just above 

 it. In the latter the beavers live, the opening being under 

 water, so that the beaver can escape if attacked. In one 

 of these strange abodes a family of from six to twelve 

 beavers lives. They separate in the spring, but return in 

 the fall to repair the winter home, which when frozen on 

 the outside is a veritable fortress. Even the fierce wolver- 



