148 COMMON BRITISH ANIMALS 



vermin. Hawks^ owls^ stoats, weasels, foxes, rooks 

 and even adders all prey largely on field mice, and 

 on the farms where these creatures were systematically 

 trapped the ground was overrun with voles, to the 

 great destruction of grass and starvation of sheep. 

 Rooks were found to be particularly useful in digging- 

 out the voles' nests and devouring the young ones.'' 



At the risk of being tedious I have quoted various 

 Avriters on the subject of vole plagues, because this 

 capacity common to the voles, hamsters, and lemmings 

 of increasing their numbers occasionally to countless 

 hosts is of considerable interest. The interest grows, 

 too, when we find that history records that our 

 ancestors suffered from similar plagues. Of the 

 plagues of voles in remote times we have no report 

 of an investigating committee, but we do learn that 

 what were believed to be the contributory causes 

 then are still so regarded. They are (1) seasonal 

 peculiarities specially favourably to the increase of 

 small mammals, as a moist autumn with plenty of 

 grass for winter cover, followed by a mild winter 

 and a dry spring ; (2) the absence of owls and 

 buzzards, and other animals that prey upon mice. 

 Thus by a thoughtless destruction of one kind of 

 animals, we may so upset the economy of Nature as 

 to produce a plague of another kind. 



When contemplating voles and vole plagues, one 

 cannot fail to be reminded of Browning's poem of 

 the " Pied Piper," who undertook, in the year 1366, 

 to rid the town of Hamelin of a plague of rats. 

 The story tells how the Piper lured the rodents by 

 his piping to their death by drowning in the Weser. 



