356 



THE NATIONAL GEOGRAPHIC MAGAZINE 



HOW DID TH^ GOLDEN PLOVER COME TO 

 USE SUCH A DIFFICULT ROUTE? 



The evolution of the elliptical route of 

 the golden plover, wonderful though it 

 is in its present extended form, is easily 

 traced through its various stages. To- 

 ward the end of the glacial era, when 

 the ice began to recede, the peninsula of 

 Florida was submerged and a compara- 

 tively small area of land in the south- 

 eastern United States was free from ice. 

 Any golden plover that attempted to fol- 

 low up the retreating ice must have been 

 confined to an all-land route from Cen- 

 tral America through Mexico and Texas 

 to the western part of the Mississippi 

 Valley. As larger areas of the eastern 

 United States were uncovered and be- 

 came available for bird habitation, ex- 

 tension of the route would be to the 

 northeast, until in time the whole of the 

 Mississippi Valley to the Great Lakes 

 could be occupied. 



As the migration route lengthened and 

 powers of flight developed, there would 

 arise a tendency to straighten the line 

 and shorten it by cutting off some of the 

 great curve (No. I, page 357) through 

 Texas and Mexico. A short flight across 

 the western end of the Gulf of Mexico 

 was finally essayed (No. 2), and this 

 gradually lengthened and its points of 

 departure and arrival moved eastward 

 until eventually the roundabout curve 

 through Texas was discarded and the 

 flight was made directly from southern 

 Louisiana across the Gulf (No. 3). 



As the great areas of Canada were 

 added to the birds' domain, other condi- 

 tions arose. Here appeared a vast new 

 stretch of coast and plain — the Labrador 

 peninsula — offering in the fall rich stores 

 of the most delectable berries and fruits; 

 but at migrating time, in the spring, 

 bound by frost and shrouded in fog. 

 Since Chinook winds made the climate 

 of the inteiior of the continent just east 

 of the Rocky Mountains especially favor- 

 able for spring migration, there arose 

 gradually a dividing of the spring and 

 fall routes, the fall route tending east- 

 ward (No. 4), while the spring route 



remained unchanged. When the fall 

 route had worked eastward to the Gulf 

 of St. Lawrence (No. 5), a shortening 

 began to take out the great westward 

 curve of the New England coast. A 

 short ocean flight was attempted (No. 

 6) ; and, when this proved successful, it 

 was extended until the present direct 

 route (No. 7) across the Atlantic was 

 obtained. 



HOW DOES THE PLOVER ElND ITS WAY 

 EVERY SEASON TO THE LITTLE HA- 

 WAIIAN ISLANDS, 2,400 MILES 

 ACROSS THE OCEAN ? 



The above gives a probable and fairly 

 satisfactory explanation of the origin of 

 the present migration route of the golden 

 plover over the Atlantic Ocean. But this 

 is a very simple problem compared with 

 that presented by the Pacific golden 

 plover. The Hawaiian Islands are in 

 the middle of the Pacific Ocean, distant 

 2,000 miles from California on the east, 

 2,400 miles from Alaska on the north, 

 and 3,700 miles from Japan to the west. 

 Golden plover in considerable numbers 

 fly each fall the 2,400 miles across an 

 islandless sea from Alaska to Hawaii, 

 spend the winter there, and fly back 

 again the next spring to nest in Alaska. 

 But how did they 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 scarcely 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 



