370 ANIMAL INTELLIGENCE. 



The beaver is a burrowing animal. Indulging this propensity, 

 he excavates chambers underground, and constructs artificial 

 lodges upon its surface, both of which are indispensable to his 

 security and happiness. The lodge is but a burrow above 

 ground, covered with an artificial roof, and possesses some 

 advantages over the latter as a place for rearing young. 



There are reasons for believing that the burrow is the normal 

 residence of the beavers, and that the lodge grew out of it, in 

 the progress of their experience, by a process of natural sugges- 

 tion. ... In addition to the lodge, the same beavers who 

 inhabit it have burrows in the banks surrounding the pond. 

 They never risk their personal safety upon their lodge alone, 

 which, being conspicuous to their enemies, is liable to attack. 

 . . . As the entrances are always below the surface level of the 

 pond, there are no external indications to mark the site of the 

 burrow, 



except occasionally a small pile of beaver-cuttings a foot 

 or more high. These, the trappers affirm, are purposely 

 left there by the beavers to keep the snow loose over the 

 ends of their burrows during winter for the admission 

 of air. 



Mr. Morgan adds the very probable suggestion that 

 this habit of piling up cuttings for purposes of ventilation 

 may have constituted the origin of lodge-building. 



It is but a step from such a. surface-pile of sticks to a lodge, 

 with its chamber above ground, and the previous burrow as its 

 entrance from the pond. A burrow accidentally broken through 

 at its upper end, and repaired with a covering of sticks and 

 earth, would lead to a lodge above ground, and thus inaugurate 

 a beaver lodge out of a broken burrow. 



It is evidence of an important local variation of in- 

 stinct, that in the Cascade Mountains the beavers live 

 chiefly in burrows in the banks of streams, and rarely 

 construct either lodges or dams. Dr. Newbury, in his 

 report on the zoology of Oregon and California, says : ' We 

 found the beavers in numbers, of which, when applied to 

 beavers, I had no conception,' and yet ' we never saw their 

 houses and seldom a dam.' Whether this local variation 

 be due to a relapse from dam- and lodge-building instincts 

 to the primitive bun-owing instinct, or to a failure in the 



