80 THE MIGRATION OF BIRDS 



of the great curve (No. 1) through Mexico and Texas, 

 and a short flight across the Gulf (No. 2) would be 

 gradually lengthened, until the present spring 

 route, then also the autumn route (No. 3), was 

 attained. As Canada opened out, the routes in 

 spring and autumn diverged ; in autumn the fruits 

 of Labrador were an attraction, but the Chinook 

 winds made the country east of the Rockies more 

 suitable for spring migration ; the fall route tended 

 eastward (No. 4), the spring route remained un- 

 changed. When the fall route had worked east- 

 ward to the Gulf of St Lawrence (No. 5), shortening 

 took place in the same way from the great westward 

 curve, culminating in an ocean flight, short at first 

 (No. 6) and later extended, the total distance 

 shortened, until the present route was attained 

 (No. 7). 



This reasoning, sound enough, helps to a more 

 difficult problem how the Pacific golden plover, 

 Charadrius fulvus, found its way to the Hawaiian 

 Islands, where numbers of the birds winter annu- 

 ally. Roughly the islands are 2000 miles from 

 California, 2400 from Alaska, whence the birds fly, 

 and 3700 miles from Japan. Mr Cooke scouts the 

 idea that any bird flies aimlessly out to sea to find 

 a new winter home, and the chance colonisation 

 by a storm-swept party is as improbable ; if this did 

 occur it is hardly likely that they would at once 



