232 BRITISH MAMMALS 



separate lengths of 5 ft. or 6 ft. Then the bark is stripped off, 

 and these round logs are rolled into position. The trees chosen 

 for felling rarely have a greater diameter than 9 in. to 12 in. 

 They are, of course, trees that grow close to the bank, and are 

 probably leaning over the water. The beaver gnaws at the tree 

 stem near the root in a circular manner, tearing out great chips 

 with his strong incisor teeth, and so directing his attacks that the 

 tree shall fall by its own weight into the stream, and not on to the 

 beaver. 



It has been thought by some authorities that the constant 

 felling of these trees is (or was originally) a provision made for 

 supplies of food, as the beaver eats bark, together with twigs, 

 roots, and perhaps leaves. The formation of these dams may, 

 therefore, have been originally accidental until the beaver dis- 

 covered what a protection to its nest was the artificial surrounding 

 of it by water. Their industry, however, in this direction, seems 

 to depend a good deal on the supplies of food, and in parts of 

 Europe (where the beaver still lingers) abundance of food away 

 from the river banks, in the shape of corn or fruit, seems to have 

 made it indifferent to the work of felling, building, and plastering. 

 The beaver progresses on land by the alternate movement of its 

 feet, not employing the jumps and bounds of the squirrel or the 

 rabbit. 



The distribution of the European beaver {Castor fiber) at the 

 present day is limited to a i&^ spots on the Rhine (where they 

 are nearly extinct), on the Rhone (but not elsewhere in France), 

 here and there in the Elbe Basin, especially in Bohemia, and on 

 the Lower Danube. The beaver still lingers on some of the 

 rivers of Western and Arctic Russia, in Poland, and on a few ot 

 the Siberian rivers. It also inhabits Norway, and it has been 

 reported to exist on the Upper Euphrates and in the Caucasus. 

 Except, however, on the Lower Danube and in Norway, where 

 it is carefully protected, the European beaver is rapidly nearing 

 extinction. The North American beaver, though closely allied 

 to the form now being described, is made into a separate 

 species, so that there is no need to discuss its range. So far 



