1 86 The Migration of Birds 



then, at the appointed time in the spring, return to 

 us across all this vast space. 



Some of these birds fly by night, others by day, 

 and some by both day and night. This was first 

 established by Mr. William Brewster, who writes as 

 follows : 



"Timid, sedentary, or feeble- winged birds migrate 

 by night, because they are either afraid to venture on 

 long, exposed journeys by daylight, or unable to 

 continue these journeys day after day without losing 

 much time in stopping to search for food. By taking 

 the night for travelling they can devote the days 

 entirely to feeding and resting in their favorite haunts. 

 Good examples are the Thrushes (except the Robin), 

 Wrens, Warblers, and Vireos. 



" Bold, restless, strong-winged birds migrate chiefly, 

 or very freely, by day, because, being accustomed to 

 seek their food in open situations, they are indifferent 

 to concealment, and being further able to accomplish 

 long distances rapidly and with slight fatigue, they 

 can ordinarily spare sufficient time by the way for 

 brief stops in places where food is abundant and 

 easily obtained. Under certain conditions, however, 

 as when crossing large bodies of water or regions 

 scantily supplied with food, they are sometimes 

 obliged to travel partly, or perhaps exclusively, by 



