MANNER OF MIGRATION, 55 
eiated with the young. Some fly by day, some by night, 
and others by both day and night. This fact was first 
established by Mr. William Brewster, who, in his admi- 
rable memoir on Bird Migration, writes: ‘ Timid, seden- 
tary, or feeble-winged birds migrate by night, because 
they are either afraid to venture on long, exposed jour- 
neys by daylight, or unable to continue these journeys 
day after day without losing much time in stopping to 
search for food. By taking the nights for traveling 
they can devote the days entirely to feeding and resting 
in their favorite haunts. Good examples are 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 con- 
cealment, and being further able to accomplish long dis- 
tances rapidly and with slight fatigue, they can ordi- 
narily 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 per- 
haps even exclusively, by night. Excellent examples are 
the Robin (Merula), Horned Lark (Otocoris), and most 
Lcteride (Bobolink, Blackbirds, and Orioles}. 
“ Birds of easy, tireless wing, which habitually feed in 
the air or over very extensive areas, migrate exclusively 
by day, because, being able either to obtain their usual 
supply of food as they fly, or to accomplish the longest 
journeys so rapidly that they do not require to feed on 
the way, they are under no necessity of changing their 
usual habits. The best examples are Swallows, Swifts, 
and Hawks.” 
While migrating, birds follow mountain chains, coast- 
lines, and particularly river valleys, all of which become 
