THE LIFE OF A BEAVER COLONY 89 
There were excellent sites for the two dams which 
would be necessary. Food was abundant, and from 
the appearance of the stream, they could count on 
an ample supply of water. They did not know 
that many years ago a small colony of beavers had 
lived there for several years, until a trapper had 
discovered their home and caught them all. That 
accounted for the grassy flat and for the division of 
the stream. In the many years which had passed 
since that tragedy the trees had grown again. 
As it was too early in the year to attempt much 
work the prospective house-builders contented 
themselves with making a deep burrow in the bank, 
with the two entrances well under water. There 
they lived for several weeks, when the stream began 
to dwindle in size as the hot weather dried up many 
of the smaller tributaries. Then it was advisable to 
commence work on the dams, and with this object 
in view they cut a number of alders and laid them 
lengthways with the banks and across the shallow 
stream. More and more were added, with clumps 
of sod and mud worked in on the upper side, so that 
the flow of water was retarded. At the end of a 
week, a small pond began to form. This grew 
larger as the dams were made more solid. At first 
the large one was not more than twenty-five feet 
in length, but the engineers decided that if they 
wanted a pond of sufficient size the length must 
be extended, and so they built on to the struc- 
tures until they were nearly doubled in size, and 
