THE ST. KILDA WREN 73 



separated from the Continent, or we can suppose that they 

 were peopled by a migrating flock of Willow Grouse that 

 were compelled by severity of climate and scarcity of food to 

 retire southwards. In either case their isolation effectually 

 preserved the variations which arose through their change of 

 country and climate, and the Eed Grouse was developed into 

 an island species from the colony of imprisoned Willow 

 Grouse, or its common ancestor. 



I was fortunate enough to discover some four years ago 

 another very similar instance to the foregoing, only a trifle 

 more local in its character. During a visit which I paid to 

 the little group of remote islands known collectively as St. 

 Kilda, I shot an example of a Wren which I found to be very 

 common there. I noticed its presence almost as soon as I 

 landed on these lonely islets. My attention was directed to 

 it more specially because it differed in many important 

 particulars from the little Wren with which we are all so 

 familiar. In the first place, it is larger, and its feet are much 

 less slender than those of the Common Wren ; secondly, it is 

 paler in colour, and has the upper plumage much more dis- 

 tinctly barred ; and thirdly, its habits are different. This 

 little bird, though closely allied to the Common Wren and 

 the Wrens living in Norway and the Faroe Islands, is still 

 very distinct from them. It has been isolated from its 

 companions so long on St. Kilda that the differences which 

 have been developed through climatic and other causes have 

 finally become constant characters, precisely as in the case of 

 the Eed Grouse. 



But very few land -birds live in St. Kilda, and of these 

 the little Wren is perhaps the only constant resident. It 

 never leaves the islands ; summer and winter its cheery little 

 song may be heard from all parts of the rocks. The Wheat- 

 ear comes to St. Kilda in spring, and stays to rear its young ; 

 the Starling breeds here, curiously enough in holes in the 



