360 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
occasion I happened to be close by when an old beaver on the inside 
stuffed and plastered up with mud and sticks a hole that had been 
dug by a mink through the walls of the house. The sticks were 
pushed into the hole and then mud pushed in around them until 
light, air, and troublesome neighbors were excluded. 
All of the building must be done before the water freezes over 
and the houses are buried in snow, and the beavers shut in for the 
winter. With frozen walls there is little danger from outside 
enemies. The bears are asleep in their own winter dens and trappers 
are prohibited by laws from cutting into or disturbing beaver houses, 
even where beaver trapping is allowed. Where trapping is not 
allowed winter is the season of safety and comfort for the beaver 
folk, for the water under the ice can not get colder than the freezing 
point, the room in the beaver house is kept warm by the heat of 
the animals’ bodies, and the food supply is convenient and generally 
ample. Just how this life is carried on will not be fully known 
until some of the beavers are tamed so that it will be possible to 
enter their houses through a “ back door ” without disturbing them, 
or get them to live in houses which we may build with modern im- 
provements to suit their taste and our convenience. This will be 
necessary before beavers can be successfully raised in captivity, as 
the success of this branch of the fur industry will depend on a full 
knowledge of the habits, dispositions, and requirements of the 
animals. . 
