134 ANNALS OF SCOTTISH NATURAL HISTORY 



rabbit producing island, and the effect on the other fauna will also 

 be disastrous. It is difficult, if not impossible, to suggest a cure, 

 but if any such can be found there is no more favourable spot on 

 which to operate, for the Craig, lying as it does about eight miles 

 from the nearest point on the mainland, the vermin cannot, unless 

 by a chance similar to their introduction above noted, receive any 

 outside accession to their numbers. In the meantime, the vermin 

 are masters of the situation, against the united efforts of the in- 

 habitants and their canine assistants. J. MACNAUGHT CAMPBELL, 

 Kelvingrove Museum, Glasgow. 



Melanie Variety of the Rat (Mus decumamis, Pallas) in North 



Uist. I send you a Black Rat which was caught in the larder here, 



Sponish House, Loch Maddy, on the i2th of November last. We 



caught altogether five in about a week, so that a party of them must 



have come in. JAMES GRAY WEBSTER, Loch Maddy. 



[We have examined the specimen and find it to be the melanic 



form of the Common Rat described by Thompson (P.Z.S. 



1837) as the Irish Rat (Mus hibemicus}. This form is not 



uncommon in Ireland, and was first recorded for the Outer 



Hebrides from Benbecula in 1888. It appears to be extremely 



rare on the mainland of Britain. EDS.] 



Notes on the Vole Plague. I do not blame the destruction of 

 vermin for the great and sudden increase of Voles (Arvicola agrestis, 

 Schreber), otherwise they might have been as numerous as they 

 now are at any period, and all the time during the past thirty 

 years other micro-mammalia have not unduly increased. During 

 the period between early in 1889 and up till August 1891, the 

 weather throughout this district was much below the average in 

 rainfall, and wells, springs, burns, and rivers were getting abnormally 

 low. The hills hereabouts hold water like a sponge. The long 

 continued dry weather reduced this moisture so much as to permit 

 (on the hills only) quite a luxuriant crop of herbage in 1890 and 

 1 89 1, which covered up the nests of young voles from the crows and 

 rooks the latter are their most effective natural enemy. It is amaz- 

 ing how greedily they hunt up and devour the young "blind mice." 

 Then the dry weather in the earlier months of the summer allowed 

 the voles comfortable healthy nests. So you have only to figure up 

 what can be done in the way of fecundity by one single pair of voles 

 and their offspring in one single breeding season to realise how 

 difficult it is for the bucolic mind to believe the voles did not drop 

 from the clouds. I have found nests of young blind voles at the 

 end of March, even in damp meadows, and again about the last week 

 in September, and they the same pair would have young number- 

 ing from six to eight or sometimes ten in each intervening month. 

 The voles are spreading westward that is, were doing so at close 

 of last breeding season. ROBERT SERVICE, Maxwelltown. 



