WHY BIRDS TRAVEL 



The Bobolink and many other birds begin 

 their journey to winter quarters before the sum- 

 mer is half over. They stay only long enough to 

 rear their broods and get new suits of feathers; 

 then they are off on the first stages of their four- 

 thousand-mile journey to southern Brazil. Thus 

 we see that they travel eight thousand miles every 

 year to spend only about two months on their 

 nesting ground. What is it that causes them 

 to undertake this remarkable journey with all its 

 many dangers? Why can they not nest in the 

 great campos and marshes of southern Brazil 

 and northern Paraguay just as well as in the 

 meadows of Massachusetts? 



When I have been studying birds in April in 

 tropical countries in Cuba, Yucatan, Colom- 

 bia, or Trinidad I have often seen flitting about 

 with the native tropical species, many of our 

 own summer Warblers, Vireos, and Flycatchers. 

 At this time the rainy season was approaching. 

 Trees were blooming, some fruits ripening, in- 

 sects becoming more numerous. But in spite of 

 this increase in the supply of food, and the fact 

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