GEOGRAPHICAL ASPECTS 75 



wide-reaching areas in the north and east. These far-off 

 northern destinations are reached by following two great 

 routes, one of which, the main one, traverses the east 

 coast of Britain ; the other, with several branches, 

 traverses the west coast and the Irish shores. After 

 arriving on our southern coast-line, the birds skirt the 

 Channel shores until they reach its eastern or western 

 limit, whence they strike a northerly course. 



East Coast of Britain. — On the shores of Kent the 

 south coast migrants about to proceed northwards 

 receive a great many recruits from the opposite side of 

 the narrow waters of the Straits of Dover.^ The east 

 coast is then followed and the waters of the North Sea 

 are crossed in a north-easterly direction at many points 

 between the Humber and the Island of Unst, the 

 northernmost of the Shetland group, to reach the 

 Norwegian coast. A number of birds, belonging to 

 comparatively few species, on reaching the Orkneys and 

 Shetlands, proceed in a north-westerly direction to the 

 Faroes, Iceland, and Greenland (see p. 82). 



Though vast numbers of the migrants journeying to 

 northern Continental Europe regularly visit Orkney and 

 Shetland, yet there is a considerable falling off in the 

 numbers of a few species, especially among the Hirun- 

 dinidae (Swallows, Martins, and Sand-Martins), the main 

 body of which evidently fly across the North Sea ere 

 these northern archipelagos are reached. On the other 

 hand, the ranks of the travellers along our eastern 

 shores are reinforced at these northern archipelagos by a 



* At the Varne lightship, situated in the mid waters of the Straits of 

 Dover, migrants are observed proceeding from the French coast to that of 

 Kent by a flight from S.E. to NAV. in spring, and in a reverse direction in 

 autumn. 



