250 MOSTLY MAMMALS 
The dam, which was about fifteen feet in length, with 
a cross-section of some two feet, was entirely made in the 
course of three weeks during the summer of 1890. In 
Canada, when the dam is sufficiently stout, the pool will 
eventually silt up and form a “ beaver-meadow,” but Mr. 
Collett does not record any of these “meadows” in 
Norway. 
During the cold winter months the beavers, although 
not hibernating in the proper sense of the term, pass what 
appears a somewhat dull existence in the central chamber 
of the lodge, the roof of which for most of the time is 
buried in snow. Sometimes, however, when the weather 
is mild for the season, and an unusually cold autumn has 
prevented the completion of the annual repairs at the 
proper time, the beavers will venture out from their 
retirement for a short period in order to remedy such 
dilapidations as stand in urgent need of immediate atten- 
tion. When they have been engaged on such works their 
footprints are visible in the snow. Immediately after the 
breaking up of the ice in spring the animals issue forth 
to procure a fresh supply of food and resume their daily 
avocations. 
The young beavers are born in April or May, three 
being apparently a common number in a litter. At first 
their eyes are closed, but they grow rapidly, and by 
September or October are about the size of a cat. When 
able to shift for themselves, they leave the parental lodge, 
and frequently start off to found a family in some fresh 
locality, although sometimes they set off on their wanderings 
alone. Following the courses of small streams, they 
frequently track straight across the open mountain-slopes 
for many miles, so that one or more not infrequently 
make their appearance in valleys where none have been 
