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 luc 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 Eagle 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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