Natural History 403 



The Story of the Beaver 



The Beaver is an aquatic mammal of a very different type, 

 suited for rivers traversing wooded country. It is a thick-furred, 

 plump creature, about 2^2 f ee t l n g with a flat, trowel-like scaly 

 tail. It swims well with its webbed hind-feet and broad tail; 

 it can remain about two minutes under water ; it feeds mainly on 

 bark. Its simplest home is a burrow with an entrance under 

 water, but above the burrow there may be a surface pile of sticks, 

 and from this rough-and-ready shelter there are gradations lead- 

 ing to a well-formed "beaver lodge" of sticks and grass, moss and 

 mud. This includes a comfortable central chamber, with a "wood 

 entrance" and a "beaver entrance." But the architecture varies 

 with individuals and with the severity of the conditions of life. 

 With more leisure, there is more art. 



Beavers can cut down trees 10 inches in diameter; they use 

 their chisel-edged incisor teeth, covered in front with orange- 

 coloured enamel, to split off flakes of wood all round the base of 

 the stem, but more towards the side nearer the water. The wind 

 then brings the tree down, and the beaver's object is attained, 

 namely, getting at the more palatable wood on the younger 

 branches. These are cut into suitable lengths and stored in or near 

 the lodge. The barked pieces may be added to the building. 

 There is no doubt that beavers make dams of brushwood, stones, 

 and mud, thereby securing a larger area for their wood-cutting 

 and easier conditions of transport. It is likely enough that 

 some of the dams were started naturally by floods which car- 

 ried lodges and stores away and deposited them in shallow 

 water; indeed, we can see the beginning of such a dam in many 

 a river in wooded country. But the point is that the beavers 

 strengthen, elaborate, and regulate what the river itself may have 

 begun. 



Even more remarkable is the digging of canals, by which the 

 transport of the cut branches is made easier. They may be 

 hundreds of feet long, and they are often about a yard broad and 



