BEAVER — DAMS. 
373 
elevated ground on which the deciduous trees are found, over 
the uneven but generally descending surface to the pond. . . . 
After one of these cuttings has been transported to the water, 
a beaver, placing one end of it under his throat, pushes it before 
him to the place where it is to be sunk. 
The sinking is no doubt partly effected by mere soaking ; 
but there is also some evidence to show that the beavers 
have a method of anchoring down their supplies. Thus 
they have been observed towing pieces of brush to their 
lodges, and then, while holding the large end in their 
mouths, 6 going down with it to the bottom, apparently to 
fix it in the mud bottom of the pond . 5 A brush -heap 
being thus formed, the cuttings from the felled trees are 
stuck through the bruslrwork, without which 4 protection 
they would be liable to be floated off by the strong currents, 
and thus be lost to the beavers at the time when their 
lives might depend upon their safe custody . 5 
Lastly, as a method whereby the beavers can save 
themselves the trouble of cutting, transporting, and 
anchoring all at the same time, they are prone, when cir- 
cumstances permit, to fell a tree growing near enough to 
their pond to admit of its branches being submerged in 
the water. The animals then well know that the branches 
and young shoots will remain preserved throughout the 
winter without any further trouble from them. But of 
course the supply of trees thus growing conveniently near 
a beaver-pond is too limited to last long. 
We have next to consider the most wonderful, and I 
think the most psychologically puzzling structures that are 
presented as the works of any animal; I mean, of course, 
the dams and canals. 
The object of the dam is that of forming an artificial 
pond, the use of which is to afford refuge to the animals 
as well as water connection with their lodges. Therefore 
the level of the pond must in all cases be higher than that 
of the lodge- and burrow-entrances, and it is usually 
maintained two or three feet above them. 
As the dam is not an absolute necessity to the beaver for 
the maintenance of his life — his normal habitation being rather 
natural ponds and rivers, and the burrows in their banks- it is. 
