MIGRATION IN THE BRITISH ISIANDS. 



243 



migration, but they are subject to an immense 

 amount of local modification. Thus all or nearly 

 all the great indentations of the coast are skipped 

 by land birds (Waders keep much more closely to 

 the windings of the coast, especially such as afford 

 suitable feeding-grounds), which make a practice of 

 flying from one headland to another. The normal 

 fiy-line, for instance, down the west coast of 

 England from Scotland misses all the English 

 coast-line of the Irish Sea, and crosses from the 

 Mull of Galloway, via the Isle of Man to Anglesey. 

 In the same manner many of the wide Scottish 

 Firths are crossed, as well as many of the more im- 

 portant promontories. Doubtless these practices are 

 general among migrants throughout the world, for 

 there is nothing to lead us to presume that the 

 British Islands are abnormal in this respect. One 

 or two local lines of Migration have also been 

 indicated, such as across the narrow country 

 between the Firths of Clyde and Forth ; and across 

 England from the Wash to the Bristol Channel, 

 onwards probably to Ireland. 



Owing to the much more rocky character of the 

 east Scotch coast-line than that of the east of 

 England, the waves of Migration are more or less 

 compressed into the various Firths and river-valleys, 

 which serve as the passages to and from the inland 

 districts, such as the Pentland and Moray Firths 

 and the Firth of Forth. On the eastern coast of 

 England, where the sea-board is low, a more general 

 ingress and egress is made, although there is 



