THE BEAVER IN NORWAY 249 



said, is carried out in autumn. Spring and autumn floods 

 also frequently submerge the lodges, from which large 

 portions are loosened and swept away. From twenty to 

 thirty years is the probable period during which a lodge 

 is habitable. 



On the bank of the river in the neighbourhood of the 

 lodge numerous burrows are met with, a few of which are 

 in connection with the lodge, although most are entirely 

 separate. Burrows are the first refuges formed by the 

 beaver when taking possession of a fresh spot, and they 

 may accordingly be likened to the rude sheds erected by 

 workmen employed on building a mansion. Probably 

 each lodge is tenanted only by a single couple and their 

 young family, the young beavers, when able to do without 

 parental assistance, either settling down temporarily in 

 burrows in the immediate neighbourhood, or wandering 

 away to found new colonies. Small lodges constructed in 

 a kind of jerry-building fashion appear to be run up by 

 bachelor beavers who have not yet ventured to take upon 

 themselves the responsibilities of a wife and family. There 

 may, however, be also spinster beavers to whom such 

 accommodation is also necessary it is to be hoped only 

 temporarily. 



Dams are constructed where beavers have quartered 

 themselves by the sides of gently flowing streamlets, or 

 small ponds through which a current runs, in order to 

 obtain water of sufficient depth and maintaining a constant 

 level. The dam is substantially built and difficult to 

 demolish. One examined in 189$ was constructed at the 

 outflow of a small stream through a forest-marsh ; and 

 where there was formerly but a small shallow pool, a 

 pond or lake of some few hundred yards in diameter soon 

 resulted from the labours of these indefatigable rodents. 



