208 STUDIES IN BIRD-MIGRATION 



Their in-comings in small numbers continue until the 

 middle of the month, after which there is an increase, 

 which is maintained until mid- May, after which date 

 the immigration practically ceases. 



After their arrival on our southern sea-board, some 

 of the immigrants tarry for a while before resuming 

 their journey. Others soon move northwards, the great 

 majority proceeding by the western routes, where there 

 are instances of the bird's appearance, even in the 

 Clyde area, soon after mid- March. With April the 

 general advance northwards sets in, and proceeds until 

 about the middle of May ; but the rearguard is observed 

 on its march northwards at the Shetland Isles, down to 

 the latter days of the month. 



On the west coast, we are able to trace the passage 

 from the Scilly Isles and Cornwall to the Welsh coast, 

 the Isle of Man, the Sol way and Clyde areas, and hence 

 coastwise to Cape Wrath, the north-western limit of 

 the mainland of Great Britain. In Scotland two more 

 western routes are also followed, the outermost of 

 which traverses the Hebrides from Barra Head, their 

 southern extremity, to the Butt of Lewis, at their northern 

 apex, while a number of the migrants visit the still more 

 outlying Monach, St Kilda, and Flannan groups of 

 islands, and North Rona. Another line of flight is via 

 Dhu Hearteach, Skerryvore, and the inner islands, and 

 comes especially under notice at Tiree and Coll. 



To turn now to the Irish coasts, we find that there 

 are only a few records for the spring passage for the 

 east coast of Ireland, but it will indeed be a very 

 surprising fact if the bird is not on regular passage 

 along that coast-line. The west coast of Ireland is, 

 however, regularly visited, and probably the birds 



