48 ROMANCE OF THE BEAVER 



prevailing conditions. In the photograph there 

 is an example of how cleverly the small creatures 

 utihsed an immense boulder in the middle of a 

 rapid flowing stream. Rocky bedded waterways 

 offer many and serious difficulties to the beavers, 

 for it is hard to get anchorage, and in this 

 particular case the current was so swift that to 

 build a successful dam required unusual skill. 

 Evidently the beaver made a thorough investiga- 

 tion of the little river and finally selected what 

 was about the only reasonably good place for their 

 operations. The large boulder acted as a support 

 or anchor for their work (this can be plainly seen in 

 the photograph), so that when the structure, which 

 was over four feet high, was finished, it resisted 

 the flow of water and formed a fair-sized pond and 

 an island on which the beaver built their lodge. 



Some writers have claimed that the animals 

 begin their dams by felling a large tree across the 

 stream. This may be true, but I have never seen 

 an instance of it. What does often happen is that 

 a fallen tree lying across a stream suggests a good 

 position for the dam, or a floating log carried down 

 during the spring thaws becomes lodged against 

 the stream banks so that the beaver take advantage 

 of it and build against it. Except under conditions 

 of this kind it is unusual to find the timber, whether 

 stick, brush or log, placed so that it lies in any 

 way but with the course of the stream. This is 

 reasonable enough when we consider how little 



