The Birds’ Calendar 
case of aérial birds the altitude of the nest is 
about in the plane of their average flight, and 
while the little vesper sparrow selects a tussock 
of grass in which to build, the grand and lone- 
ly mountain is the foundation of the eagle’s 
home. Among aérial birds, too, there is an 
irregular parallelism between the size of the 
bird and the height of the nest—many war- 
blers and sparrows choosing the ground, or 
a slight elevation, the larger finches, crows, 
hawks, and eagles going successively higher 
and higher. 
A constant thought of a bird is, ‘* Many are 
they that rise up against me,’’ and safety is 
commonly the first consideration in the loca- 
tion of nests. In this they are materially as- 
sisted by the generally inconspicuous colors of 
the female, and among the sparrows, which 
mostly nest on the ground, so that the eggs 
and young are especially exposed to the depre- 
dations of other animals, by the neutral color- 
ing of both sexes. The Maryland yellow- 
throat finds security in the seclusion of low 
bushes, the red-eyed vireo in the manifest ex- 
posure of the tip-end of a branch, in a ‘ priv- 
acy of light,’’ and the bobolink concludes to 
run his chances by camping down on the open 
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