DISTANCES TRAVELLED BY BIRDS 77 



plentiful and during the earlier part of the journey 

 northwards only a few miles are covered per day ; 

 they travel with the slowly advancing vernal wave, 

 but, as we shall show in the next chapter, many 

 species actually outstrip it, and travel from warmer 

 to colder climates, 



By the kind permission of Mr Cooke I am able to 

 reproduce three of his maps, illustrating the longest 

 known distance travelled by any bird in a single 

 flight, and the probable evolution of this extra- 

 ordinary oversea voyage (21). This long journey, 

 roughly 2500 miles at a flight, is used in autumn 

 by several species of American shore birds, and the 

 particular species most easily recognised, is the 

 American golden plover, Charadrius dominions, 

 which differs but little from our C. pluvialis. An 

 important point to notice is that the route followed 

 in the fall is not the one used by the bird in spring, 

 an undoubted proof that all routes are not identical 

 with the original line of dispersal of the species. 

 Nor is the route directly from the north to the south, 

 though there is plenty of evidence to show the 

 fallacy of the notion that all birds move in this one 

 direction. 



The golden plover nests along the Arctic coasts 

 of North America from Alaska to Hudson Bay. 

 So soon as the young are able to take care of them- 

 selves the birds migrate south-east to Labrador, 



