ROUTES OF MIGRATION 231 



still crossed between Greenland, Iceland, and the Faroes, 

 and between the south of Ireland and the Lizard, as 

 they were in remote ages traversed when dry land, or 

 nearly continental dry land, replaced them. Most of 

 these birds, it will be remarked, are aquatic, able to make 

 long flights across the sea, powerful of wing ; and it is 

 possibly due to these facts that they have been able to 

 conform to the Law of Migration so successfully and so 

 long, notwithstanding the enormous change which has 

 taken place along their recognized routes — now only 

 rendered visible in some cases by an isolated island here 

 and there, which may serve as a welcome landmark or a 

 possible place of rest. We thus see again that the wide 

 water areas are no obstacle to species that acquired the 

 habit of crossing them when they were dry land, 

 although they are barriers to emigration and range 

 extension which no species attempts to pass. 



These Routes unquestionably are most followed along 

 our eastern coasts, due not only to the greater land 

 mass of Scandinavia lying nearest to that area, but to 

 the fact of the Shetlands assisting in deflecting a great 

 deal of it east. Most of the species that follow them 

 are coast birds, and they chiefly keep to the coast-lines 

 on their way to their northern or southern destinations. 

 We have one important Route from Scandinavia, not 

 only by way of the Shetlands and Orkneys, but right 

 across the North Sea in a south-westerly direction to the 

 Scotch coast. The former portion of this Route divides 

 at the Orkneys, one continuing down the east coasts of 

 Scotland and England, the other following the west 

 coast of Scotland to Ireland and the west coast of 

 England. Another Route, followed, however, by few 



