THE MIGRATIONS OF THi: SONG-THRUSH 217 



During the period in which ordinary climatic con- 

 ditions prevail, little or nothing is recorded. In others 

 the few local movements are traceable to topical weather 

 conditions. But sooner or later during each season 

 great outpourings take place, often extending over 

 several successive days and nights and affecting all our 

 coasts. The Thrushes affected are not merely our would- 

 be resident birds, but a very large proportion of them 

 are, no doubt, the immigrants lately arrived from the 

 north, which, as winter visitors to our islands, remain 

 until compelled to move further south or west. 



The first move on these occasions is to the coast, 

 especially the west coast and its off-lying islands, where 

 some tarry, and even remain to perish. Others pass 

 along both the east and west coasts of Great Britain ; 

 many of those following the former route sweeping 

 along the south coast westward, and crossing the 

 channels for the Continent and Ireland. Many, too, 

 seek Ireland from the north and east. Emigrations 

 from the Sister Isle are also recorded during winters of 

 exceptional cold. 



Should the cold spell be of great severity, or be 

 seriously prolonged and widespread, many perish even 

 in such usually safe retreats as the Scilly Isles, and at 

 Valentia, or other isles off the west coast of Ireland, which 

 are largely sought on such occasions. No doubt, too, 

 many of the emigrants perish in their Continental 

 asylums, for after winters of almost arctic severity, such 

 as that of 1880-8 1,^ the Thrush was conspicuous by its 

 absence, or by its scarcity, in most districts in our islands. 



' During this winter twenty days of hard frost and sixteen days of deep 

 snow prevailed on the west coast of Ireland. It was much more severe 

 elsewhere. See Chapter VII. for further instances of severe seasons. 



