86 



Marvels of the Universe 



BEAVERS AND THEIR WORK 



Photo f)!/] 



[iVfir York Zoological Society. 



THE BEAVER. 



The broad flattened tail is well shown in this photograph. It 

 formerly thought that the beaver used it as a trowel. 



BY R. LYDEKKER 



Beavers have the distinction of being the only mammals that, under certain circumstances, per- 

 manently alter the configuration of the districts they inhabit. Such changes are produced in the 



first instance by the dams of timber, 

 boughs, mud, and stones which these 

 rodents construct across rivers, in 

 order to extend the expanse of smooth 

 water, or to obtain sufficient depth for 

 their evolutions, and to enable them 

 to enter their subaqueous burrows 

 when the surface is frozen. Such 

 dams often have a length of five 

 hundred feet or more, with a height 

 of twelve or thirteen feet, and a basal 

 width of twenty feet ; the thickness 

 tapering from the base till it becomes 

 only about a yard at the summit. 

 Rarely the dam may be about a mile 

 in length. 



Above the dam the water is headed 

 up so as to form a pond or lake. In 

 the course of centuries the lake silts 

 up, by the aid of mud and vegetable growth, till eventually a plain of rich soil is formed, which, 

 when clothed with grass, is called a beaver-meadow, and forms a new feature in the landscape. 

 As an instance of the extent of these meadows and their drainage canals, it may be mentioned 



that the name of the Indian village 

 which formerly occupied the site of 

 Montreal means beaver-meadow. 



Beavers are confined to Europe, 

 Northern Asia, and North America, 

 and in prehistoric times inhabited the 

 English fens. Nowadays, they are 

 almost exterminated in Europe, al- 

 though pairs or colonies survive on 

 the Elbe and Rhone, and in parts of 

 Scandinavia. Occasionally these con- 

 struct dams, but they generally live 

 in burrows. In Canada, although their 

 engineering skill has been overrated, 

 they fell trees of considerable size 

 for their dams by gnawing through 

 the stem a foot or so above the 

 ground ; such trees generally leaning 

 over the water, and therefore falling 

 From the subaqueous entrances to their burrows they frequently build 



in other cases, the structure 



[.\>ir Y.irk /.nol,„ji,;iI : 



BEAVER. 



This beaver has started 



>ff on the search for further materials for 

 lodge building. 



in the right direction 



mounds of brushwood and mud, which are known as " bank-lodges 



