THE STARLING 117 



spreading over the south of Scotland, it was 

 still quite unknown over the greater part of 

 the centre and north ; but to this there were 

 very remarkable exceptions. There is unim- 

 peachable evidence that the starling has been 

 resident in numbers in Orkney and Shetland, 

 in the Outer Hebrides and the extreme north 

 of Caithness ' from time immemorial ' ; it may 

 be noted, in proof of its long residence, that the 

 Highlanders have for it their own Gaelic name 

 ' Druid.' 



The invasion of Scotland by the starling has 

 been exhaustively treated by Mr. J. A. Harvie- 

 Brown, 1 as also in his series of volumes on The 

 Vertebrate Fauna of Scotland. The question of 

 the actual causes of such dispersals is a large 

 one, and it must suffice here to say that it seems 

 probable that, as a rule, such movements are 

 caused by pressure arising from congestion of 

 numbers in the older centres ; so that the super- 

 fluous population is forced to overflow and to find 

 a passage along the lines that are to them those 

 of ' least resistance.' Thus, while the advancing 

 wave was pushed northward from England, 

 the Outer Islands had probably received their 

 quota long before, from the old-established 

 colonies in Orkney and Shetland. Whence 



^Annals of Scottish Natural History, January, 1895. 



