Birds of North America and Europe compared. 179 



sents regions not exceeding 800 feet above the level of the sea, 

 and its western margin the limits of the eastern region. Thus 

 it will be observed that the northern boundary of the western 

 division turns westward at the mouth of the Mackenzie River 

 along the shores of the Arctic Sea. Now as to the general 

 directions of bird migrations, they are in all continents, from 

 north to south, along shore lines, valleys, and mountain chains. 

 A glance, however,. at the maps of Europe and America will 

 suffice to show the advantages possessed by the New World 

 in these respects, chiefly in its rivers, mountain ranges, and 

 depressed lands trending in the direction of the routes of 

 the bird wanderers, whereas the Alps and Mediterranean Sea 

 appear to present obstacles to the birds of passage on their 

 way to and from Africa and Northern Europe ; but whilst 

 not very much influencing their movements, there can be no 

 question that they stand in the way of the distribution of 

 mammals and other animals, which in North America are 

 free to roam over vast tracts of country from north to south. 



With reference to the especial direction pursued by the 

 birds during their migrations, it has been found that the birds 

 of the eastern regron go to and return from their summer 

 and winter quarters by the Atlantic coast and the great valley 

 of the Mississippi, whilst the western species hug the shores of 

 the Pacific and the western slopes of the Rocky Mountains; and 

 while the majority of the birds of the former division take 

 up their winter quarters in and around the Gulf of Mexico, 

 Florida, and the West Indies, a small portion only going into 

 South America, it has been observed on the other side that 

 very few go further south than the Pacific shores of Mexico. 

 Thus the winter visitors to the West Indies are, with very few 

 exceptions, summer residents in the north-eastern portion of 

 the United States, Canada, and the Arctic Regions. It will 

 be observed that the peculiar tongue-shaped promontory of 

 Florida protrudes on the coast, having Cuba and the Bahamas 

 at its apex. We would therefore expect, from what has just 



