182 



OUR GREATEST TR.VVELERS 



MAP SHOWING THE PRINCIPAL ROUTES 



USED BY BIRDS IN THEIR MIGRATIONS 



BETWEEN NORTH AND 



SOUTH AMERICA 



The different courses taken by the 

 birds to get around or over this inter- 

 vening inhospitable region are ahnost as 

 numerous as the bird famihes that trav- 

 erse them, and only some of the more 

 important ones are shown on the accom- 

 panying map. The routes are numbered 

 from the east westward. 



The middle route, No. 4, is by far the 

 most important. In general it may be 

 said to e.xtend from northwestern Flor- 

 ida and western I^ouisiana across the 

 Gulf of Mexico to the southern coast of 

 the Gulf (Yucatan to Vera Cruz), and 

 thence by land through Central America 

 to South America. Probably more indi- 

 viduals follow this route than all the 

 other routes combined. 



The birds east of the Alleghany Moun- 

 tains move southwest in the fall approxi- 

 mately parallel with the seacoast, and 

 most keep this same direction across the 

 Gulf to eastern Mexico. The birds of 

 the central Mississippi Valley go south- 

 ward to and over the Gulf. The birds 

 between the Missouri River and the edge 

 of the plains, and those of Canada east 

 of the Rocky Mountains, move south- 

 eastward and south until they join the 

 others in their passage of the Gulf. 



In other words, the great majority of 

 North American birds bound for a win- 

 ter's sojourn in Central or South Amer- 

 ica elect a short cut across the Gulf of 



^Mexico in preference to a longer land 

 journey by way of Florida or Texas. In 

 fact, millions of them cross the Gulf at 

 its widest part, which necessitates a single 

 flight of 500 to 700 miles. 



The peninsula of Florida extends far 

 to the south, and the great island of 

 Cuba forms a convenient stepping-stone 

 between its coast-line and Yucatan. A 

 bird taking this highway would avoid 

 any long single flight : >'et, with the ex- 

 ception of a few day-migrating swallows, 

 no bird is known to follow this route. 

 A probable explanation is that southern 

 Florida has vastly less bird food per 

 square mile than the countr}' to the 

 northward, and the birds prefer a single 

 long flight with abundant rations to a 

 series of shorter flights on scantier fare. 



^ligration route No. 3, which is by 

 way of Cuba and Jamaica, oft'ers a much 

 shorter journey to South America, but it 

 is traversed by only a few species. It is 

 popular as far as Cuba with some 60 spe- 

 cies, of whom great numbers spend the 

 winter on the island ; about 30 of these 

 species have a small contingent who pass 

 on to make Jamaica their winter resort ; 

 but scarcely more than 10 species try the 

 final long flight across the Caribbean Sea 

 to South America. .Vmong these are one 

 species each of six widely difliering fami- 

 lies — the bank swallow, gray kingbird, 

 Florida nighthawk, Alice thrush, black- 

 poll warbler, and bobolink. The other 

 members of those families employ en- 

 tirely different migration routes. 



It is not possible to ascertain whether 

 these travelers on the so-called "bobolink 

 route" represent adventurous species that 

 are seeking to improve on the round- 

 about course through JMexico, or old 

 fogies who hold to the way of their fore- 

 fathers long after their brethren have 

 proven to their own satisfaction the su- 

 perior advantages of the more western 

 route. 



The next route to the eastward. No. 2, 

 traverses the chain of islands that ex- 

 tends from Florida to South America. 

 This, too, is considerably shorter than 

 the Florida-Yucatan route, and land can 

 always be kept in sight ; yet this line also 

 is discredited. A few individuals of 

 about 25 species follow it as far as Porto 



