MIGRATION OF BIRDS. 25 
Humming Bird, which, although swift of wing, is 
often among the last in the train. 
Birds frequently perform their migrations at night, 
halting at convenient distances, sometimes spending 
many days in a congenial spot, and only leaving it 
as the advance of the season warns them of the ne- 
cessity of completing their journey. The rapidity 
with which some species travel through the. air on 
these occasions, has been the subject of much specu- 
lation. It is a well-ascertained fact that their swift- 
ness is so great as far to surpass any speed which it 
is in the power of man to produce, and has been 
known sometimes to be equivalent to one hundred 
miles an hour. The males generally arrive a few 
days in advance of the females, as though for the 
purpose of reconnoitering and finding out suitable 
places to locate their nests; and the coming of the 
females is a signal for the choosing of mates, and 
making general preparations for the accommodation 
of a family. 
That every distinct species constructs a nest of 
some peculiar shape, and of materials best adapted 
to its own wants, is a circumstance worthy of notice. 
The unique little structure built by the Humming 
Bird from the finest and most delicate moss, and lined 
with the soft down from different plants, while it is 
well calculated for the accommodation of its own tiny 
progeny, would hardly answer the wants of any of its 
neighbors. The Kagle rears her young upon some 
bare and inaccessible crag, where, with a heap of sticks 
and moss for a nest, she broods over them in solitude. 
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