110 ANIMAL LIFE OF THE BRITISH ISLES. 



It was found subsequently that specimens from different 

 islands in the Orkney group showed differences due to their 

 segregation over a long period, and they have consequently 

 been distinguished as five sub-species. These differences are 

 minute, and it would be wearisome and out of place in a popular 

 work such as the present to detail them. Generally speaking, 

 they are much alike, and their habits are practically identical, 

 so far as at present known. 



The runs are a conspicuous feature of the islands, among the 

 heather and the rough vegetation of the fields and hillsides, 

 running along the surface and at intervals entering tunnels 

 about two and a quarter inches in diameter just sufficient to 

 clear the spread of the Vole's whiskers. Their nesting places, 

 like those of the Mole, are under small mounds connected with 

 a network of runs. The nest itself is made of grass and roots 

 in a rounded chamber, where at intervals during the spring and 

 summer several litters, varying from three to six, are produced. 

 Before they are three weeks old they are capable of independent 

 existence, but for a time are still guarded by the mother. 



The Orkney Vole appears to be specially fond of the roots of 

 Heath Rush (Juucus squarrosus\ but also feeds on grass and 

 the crops in cultivated fields to which they can gain access. 

 Mr. Millais found that in cold weather his captive Voles became 

 inactive. It has many enemies to hold its increase in check, 

 for every bird and beast large enough to capture it will eat it 

 readily. 



Bank Vole (Evotomys glareolus, Schreber). 



There can be little doubt that in many places the Bank Vole 

 has been mistaken for a bright variation of the Field Vole. Its 

 habits are much the same, except that it haunts the hedgerow 

 and wooded country rather than the open fields. As to the 

 differences between the two species, the Bank Vole's head and 

 body measurement is only three and three-quarter inches against 



