n 



for beaver to go about. I know of two colonies 

 that were crushed out of existence by snow-slides. 



The dam is on rare occasions broken by late 

 spring ice -jams. Sometimes the ice-cakes pile 

 up on the dam and raise the water in the pond to 

 such a height that it rises in the house and drives 

 the beaver forth. A few beaver houses that are 

 situated in places where the ice or spring floods 

 may raise the water much above normal level are 

 shaped to meet this trouble. The house is built 

 higher and the room internally is twice the usual 

 height. Thus there is space for the beaver to 

 build a " platform bed " on the floor and thus 

 raise themselves a foot or more above the common 

 level. Despite all pains, floods sometimes drive 

 beaver to the housetops. 



By laying up supplies, and by the help of arti- 

 ficial pond, canal, and house, the beaver is able 

 to spend his winter without hunger and with 

 comfort and far greater safety than his neighbors. 

 The winds may blow and blinding snow or flying 

 limbs may endanger those outside; snow may 

 bury the forage of bird and deer, and make the 

 movement of beasts of prey slow and difficult; the 



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