cold may freeze and freeze and strew the wilds 

 with lean and frozen forms ; but the beaver be- 

 neath ice and snow shelter serenely spends the 

 days with comfort and safety. 



The winter, with its days long or short, never 

 comes to an end, however, quite early enough to 

 suit the beaver. They emerge from the pond at 

 the earliest moment that frozen conditions will 

 allow. If their subway is choked with ice, and 

 food becomes exhausted, they will sometimes bore 

 holes through the base of the dam. 



Apparently, too, holes of this kind are bored 

 through, or a section cut through the dam to the 

 bottom, for the purpose of completely draining 

 the pond. As this appears to be most often done 

 with ponds that are full of stagnant water, or 

 water almost stagnant, this draining may be a 

 part of the beaver's sanitary work, done for the 

 purpose of getting filth and stale water out and 

 also that the sour bottom may be sterilized by 

 sun and wind. 



Conditions determine the length of time before 

 the dam is repaired and the pond refilled. In some 

 cases this is done after the lapse of a few weeks 



208 



