REBUILDING A BEAVER COLONY 131 
canal and the edge of the pond, the foundation 
for a house was being excavated. Two tunnels 
were made through it to the bottom of the pond. 
The house was made of mud dredged from 
the bottom of the pond, and this was reén- 
forced with an entire clump of willows cut near 
by. There were also used willow roots, sods, 
a few stones, and a few peeled aspen sticks off 
which the beavers had eaten the bark, and 
which they dragged from their temporary home 
—the old house. 
The finished house was about ten feet across 
the bottom and five feet high. The walls were 
about two feet thick. The ventilation top was 
a mass of criss-crossed sticks without mud. 
Beavers do most of their work at night— 
this probably is for safety from men. It appears 
that at one time they may have regularly worked 
during the daytime. But for generations hunt- 
ers with guns have made day work perilous. 
In out-of-the-way places where they had not 
been disturbed I have seen a whole colony at 
work during the daytime even when the work 
was not pressing. With exceptions they now 
work daytime only in emergencies. At this 
place no one was troubling the beavers and fre- 
quently I saw an old one, and at length I realized 
that it had been the same old one each time. 
I was sitting on the side of the beaver house 
