188 



OLTR GREATEST TR.W^ELERS 



MAP SHOWING THE EVOLUTION OF THE 



PRESENT MIGRATION ROUTE OE THE 



GOLDEN PLOVER (SEE 



Page 187) 



Golden plo\'ers in considerable numbers 

 fly each fall the 2,400 miles across an 

 islandless sea from Alaska to Hawaii, 

 spend the winter there, and fl)' back- 

 again the next spring to nest in Alaska. 

 Bvit how did the}- first find their way to 

 Hawaii? 



It is not to be supposed that any birds 

 would deliberately strike out over un- 

 known seas hunting for a new winter 

 home. It is scarcel}' more probable that, 

 even if a large flock was caught in a 

 storm and carried far out of its course 

 to the Hawaiian shores, the birds would 

 change in a single season habits of count- 

 less generations and start at once a radi- 

 cally new migration route. It has already 

 been said that present migration routes 

 are evolutions — age-long modifications of 

 other routes. The problem, then, is to 

 find some migration route from which 

 the golden plover's present Hawaiian- 

 Alaskan route could have been easily 

 and naturally derived. 



The bird breeds on the northern shores 

 of eastern Siberia, from the Liakof Is- 

 lands to Bering Strait, and on the Alaska 

 side of the strait south to the northern 



base of the Alaska peninsula (page 189). 

 It winters on the mainland of southeast- 

 ern Asia, in the eastern half of Australia, 

 and throughout the islands of Oceanica, 

 from Formosa and the Liu Kiu Islands 

 on the northwest to the Low Archipelago 

 in the southeast. 



The breeding range has an east-and- 

 west extension of about 1,700 miles, 

 while the winter home extends nearly 

 half around the globe — 10,000 miles — 

 from India to the Low Archipelago. 

 Undoubtedly the original migration route 

 was approximately north and south, be- 

 tween the nests in Siberia and the winter 

 resorts in southern Asia. In the course 

 of time the species spread eastward in 

 the winter to Australia, to the islands 

 along the eastern coast of Asia, and 

 throughout Oceanica, while at the same 

 time the breeding range was extended 

 eastward across Bering Strait to Alaska. 



If all these extensions took place be- 

 fore there was any cutting off of corners 

 in the migration route, then at this stage 

 of development the Alaska - breeding 

 birds were journeying over 11,000 miles 

 (page 180, No. i) to reach the Low Ar- 

 chipelago, distant only a little more than 

 5,000 miles in an air-line. 



It is fair to suppose that early in the 

 course of the eastward extension among 

 the Pacific islands, the plover began to 

 shorten the roundabout journey by flights 

 from the northern islands to eastern 

 Asia, and finally to Japan (No. 2). The 

 most northern island is Palmyra, and the 

 flight from there westward to the nearest 

 of the Marshall Islands is about 2,000 

 nfiles : thence a 3,000-mile journey, with 

 se\-eral i)ossil)le rests, brings the birds to 

 Japan. 



It is easily possible that birds accus- 

 tomed to this 3,000-mile flight might be 

 driven by storms a thousand miles out 

 of their course and discover Hawaii. 

 When from Plawaii they attempted to 

 reach Japan (No. 3) they would find a 

 chain of islands stretching for 1,700 

 miles in the desired direction, and the 

 final flight of 2,000 miles from the last 

 of these — the Midway Islands — to Japan 

 would be no longer than previous flights 

 to which they had become accustomed. 



Having once learned the route from 



