Usually there are supplementary dams placed 

 above and below the main one to reduce the danger of 

 breaking in rainy weather when the streams are swift. 

 The dam below the main dam holds the water against 

 the lower side of the latter and strengthens it. 



There are generally a number of beavers in a 

 colony and when a break occurs in the dam, all of the 

 members set to work to repair it. Each animal secures 

 a stick on the shore and immediately swims with it to 

 the break, where it is carefully placed. The sticks are 

 placed so that water flows through them and floating 

 material is caught as in a sieve and helps to plug the 

 opening in the dam. 



The beaver often lives in burrows in the banks of 

 the pond. These burrows extend for a considerable 

 distance beneath the bank and generally have their 

 openings below the surface of the water. The burrow 

 ends in a larger chamber several feet in diameter. 



Usually the beaver constructs a mound-like home 

 out in the water. This is made of sticks and mud and 

 varies in size according to the number of individuals 

 that live in it. The mound is conical and may be as 

 much as eight feet high and forty feet in circumfer- 

 ence. Inside the house and above the level of the water 

 is a chamber in which the animal lives. The entrance 

 to the hut is through a tunnel, opening beneath the sur- 

 face of the water. The walls of the house are quite 

 thick. 



In winter the beaver partly hibernates within its 

 house but ventures forth in mild weather. Food is 

 stored in the pond for winter use and the sticks from 

 which the bark has been gnawed are used in reenforc- 

 ing the dams. 



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