RECENT EMIGRATION 173 



mainland. In Ireland, too, although excessively local, 

 a marked and recent northern extension of ranc]^e is 

 apparent. It is interesting to remark that' the Wood 

 Wren is absent from Norway, and there can be little 

 doubt will never colonize the south of that country, even 

 if it succeeds in penetrating to districts further north, 

 say of lat. 60' {conf. footnote, p. 127). The individurds of 

 this species that breed in Sweden and even as far north 

 as Archangel winter probably in Abj^ssinia, hence its 

 absence from Heligoland on passage — a line of Emi- 

 gration to which we have already alluded at some length 

 in the preceding chapter. The Marsh Warbler (Aav- 

 ccphahis palustris) appears also to be spreading north- 

 wards in England, but as this species is so excessively 

 local, and its distribution by no means perfectly known, 

 it is perhaps wisest to discard this as an instance of 

 recent emigration until we are in possession of fuller 

 details. The Sedge Warbler {Acrocephalits phragmitis) 

 has either not been observed in the Orkneys until I 

 believe it was found by ]\Ir. T. P2. Buckley, or has 

 extended its range to those islands recently. The Gold- 

 crest [Regulus cristatiis) is rapidly becoming more dom- 

 inant and widely dispersed in Scotland, Gray stating 

 that seventy years ago the bird was very scarce and 

 local. It is also a significant fact that the great waves 

 of migratory individuals of this species from the East in 

 autumn, and which spread west into Ireland, normally 

 strike our coasts south of Fife, thus indicating the area 

 from which their ancestors emigrated east across the 

 then North Sea Plains in past ages, and when the Gold- 

 crest must have been a by no means dominant species 

 in Scotland, although it certainly reached Scandinavia 



