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 , 9 and yet 4 we never saw their 
houses and seldom a dam . 9 Whether this local variation 
be due to a relapse from dam- and lodge-building instincts 
to the primitive burrowing instinct, or to a failure in the 
