108 THE RIDDLE OF MIGRATION 



Alaska to Hawaii, 2000 miles across the Pacific 

 Ocean, can obviously not have developed by a proc- 

 ess of gradual spreading. It suggests a route of 

 sudden origin which is actually what it may have 

 been, possibly an incidental outcome of extensive 

 glaciation. But we must of necessity make the as- 

 sumption that this plover, before its present distri- 

 bution was adopted, was already a long-established 

 migrant. Its venture would surely have ended in 

 complete catastrophe had the case been otherwise. 

 The same may be said of the turnstone and other 

 shore-birds reaching Hawaii regularly. Sudden 

 enormous movements of birds over great distances 

 are not unknown tocJay. The periodic invasions of 

 France and Britain by large numbers of Pallas' sand- 

 grouse {Syrrhaptes paradoxus) from central Asia 

 afford one example; the precipitate arrival of hun- 

 dreds of European lapwings (Vanellus vanellus) on 

 the shores of Canada (Newfoundland) in 1927 offers 

 another. Neither the sand-grouse nor the peewit 

 are, however, great migrants and their sudden ex- 

 cursions have merely led to failure and death. But 

 these cases raise the possibility of an entirely dif- 

 ferent spontaneous origin for certain migrations, or, 

 more correctly, for certain migratory routes and 

 present distribution. But they can hardly be of 

 universal or even of wide application. 



