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months, while the others subsist upon insects in their embryo 

 forms, which, during autumn and winter are concealed in the 

 crevices of the bark of trees. 



The habits of the Fly-catchers are quite different from those 

 of "any of the species I have just named. Let us take the 

 Pewee for an example. He sits on the bough of a tree almost 

 motionless, except a frequent sidling of the head, indicating 

 his watchful condition. He does not seem to be so diligent as 

 the Sylvians ; but that he is not idle is shown by his frequent 

 flitting out, in an irregular circuit, and immediately returning 

 to his perch with a captured insect. These salient flights are 

 performed as often as once in four or five seconds, and he often 

 turns a summerset in the act of capturing his prey when it tries 

 to elude him. He seldom misses his aim, and probably col- 

 lects ten or fifteen insects every minute, of an appreciable size. 

 As he lives entirely upon them, and is also, in the early part 

 of summer, engaged in supplying the wants of his youug, this 

 is no extravagant estimate. 



The Pewee does not catch all his food while it is on the 

 wing, but he is always on the wing when he takes it. If he 

 sees a moth or a beetle upon a leaf or a branch, he flies to it 

 and seizes it while he is poised in the air. A Sylvian would 

 stand upon the branch and extend his neck forward to take it. 

 The Vireos, which form an intermediate genus between the 

 true Fly-catchers and the Sylvians, partake of some of the 

 habits of each ; and some of the species are remarkable for a 

 habit of singing while they are foraging. The warblino" Vireo 

 seems, indeed, to make singing his principal employment ; he 

 is never apparently very diligent or earnest, and often stops in 

 the middle of a strain to seize a passing insect, and then re- 

 sumes it. All the true Fly-catchers, including the Kin"--bird 

 resemble the Pewee in their general habits of foraging. 



Here, then, we observe several circles ; the outer one occu- 

 pied by the true Fly-catchers, who sit in wait for all such in- 

 sects as discover themselves flitting among the foliage of the 

 tree, or outside of it ; the circle- next the outside is occupied 

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