6960 Birds. 



Wales and the South of England, not in Scotland. North ; in 

 Russia, Sweden, Denmark, South ; in Germany, France, Spain, 

 North Africa and Cape of Good Hope. Its line of migration being 

 slightly to the westward of the nightingale, but still excluding 

 Ireland. 



Pied Flycatcher [Muscicapa atricapilla), in the like manner, whilst 

 extending as far North as Scandinavia and Central Russia, is rare in 

 the south-western shires and unknown in the north-western. 



Lesser Whitethroat {Sylvia curruca) extends into Wales, but 

 is rare there, showing that this is an outlying station. It is un- 

 necessary to multiply examples further, for the same laws will be 

 found to be more or less strictly applicable to all the regular summer 

 migrants of Great Britain unknown as such in Ireland. 



Now, it has been already shown that in the districts lying east and 

 west of the ai"ea included within the normal migratory lines of each 

 species, there occur subareas which are nearly as suitable for the well- 

 being of such species as the districts contained within these limits; 

 and hence, if by any disturbing cause a migratory bird is driven out of 

 its usual course, it may in such subareas find a spot in which it can 

 subsist, and where it will probably remain until more favoring circum- 

 stances enable it to regain its course, and if this divergence takes 

 place during its northernly migration it may possibly breed here. 



Remarkable instances of these latter phenomena are seen in Ire- 

 land among southern migrants ; in the golden oriole [Oriolus gar- 

 rula), blackcap warbler [Sylvia atricapilla), hawfinch [Fringilla 

 coccothraustes), crossbill {Loxia curvirostris), rose pastor {Pastor 

 roseus), hoopoe (Upupa epops), melodious willow wren {Sylvia tro- 

 chilus), stone curlew {CEdicnemus crepitans), dotterell {Charadrius 

 morinellus), and possibly in the grasshopper warbler {Sylvia locus- 

 tella) ; and in Great Britain, in the golden oriole, hoopoe and rose 

 pastor, &c. 



Taken it as proven, that migration takes place in a line north 

 and south, that it has fixed longitudinal limits, and that through 

 disturbing causes species occasionally transgress these limits and 

 survive, the occurrence of summer European migrants in these 

 isles is what might have been expected, — • all that has occurred is 

 this, — the birds in their passage south meeting with easterly gales 

 have been driven from their course, and, finding here localities suited 

 to their habits, remain either till spring or till a favorable moment for 

 continuing their southern journey arises. 



The instances of the occurrence of such birds in Ireland in winter 



