132 ANNALS OF SCOTTISH NATURAL HISTORY 



of which he considered 12,000 to 15,000 acres had been 

 rendered useless ; in Dumfriesshire 40,000 to 50,000 acres, 

 and in the Stevvartry of Kircudbright 10,000 to 12,000 acres 

 were described by him as infested by voles. 



Your Committee received no estimate of the area affected 

 in the counties of Selkirk, Peebles, and Lanark, nor had they 

 the means of verifying Mr. Dudgeon's calculation in respect 

 to the other counties affected ; but a reference to the map 

 accompanying this Report will show that an area not less 

 than 60 miles in length, and from 12 to 20 miles in breadth, 

 has been overrun. 



Causes of the Outbreak. 



The rapid increase in the number of voles to the dimen- 

 sions of a plague was attributed by all the witnesses examined 

 to one of two causes, or to a combination of both. The first 

 of these consists in the character of the seasons. Mr. Service 

 called attention to the occurrence of a series of dry springs in 

 1890, 1 89 1, and 1892, adducing figures to show that the 

 rainfall in these seasons was very much below the average, 

 and therefore favourable, in his opinion, to the breeding of 

 small mammals. The autumn of 1890 was unusually wet, 

 producing great luxuriance of grass on the hill pastures, which 

 afforded abundant shelter for the voles. The winter which 

 followed, though very severe in England, was a mild one in 

 Scotland. It will be observed that Sir Walter Elliot has 

 traced the cause of the outbreak of voles which took place in 

 1876 to the unusual mildness of the four or five winters pre- 

 ceding that year. 



The second cause assigned by witnesses is the destruc- 

 tion of hawks, buzzards, owls, stoats, and weazels by persons 

 interested in the preservation of game. Major Craigie had 

 previously stated to your Board that " a preponderance of 

 opinion amongst farmers is reported, tracing the cause of the 

 present outbreak to the scarcity of owls, kestrels, hawks, 

 weasels, and other vermin." Of the prevalence of this opinion 

 your Committee were made fully aware, nearly every witness 

 who was examined giving it as his belief that the outbreak 

 was due to the destruction of the " natural enemies " of the 



