186 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 
