January 



little practice to bring the glass to bear instantly 

 on the precise point ; and if not done at once, 

 the bird is likely to be so disobliging as to 

 change its position, and you will run the risk 

 of losing it altogether. It is advisable to gain 

 facility in this matter by fixing the eye on some 

 remote but distinct object, like the end of a 

 branch, and learning to cover it instantly with 

 a glass. The opportunities of seeing specimens 

 are too valuable to be wasted in such practice. 



The absence of foliage in winter makes a 

 vast difference in the ease of discovering birds, 

 and of following their motions as they go from 

 tree to tree. A delicate aspen-leaf can hide a 

 warbler, and any of the larger song-birds can 

 be lost behind a leaf of maple or of oak, while 

 the plumage often blends confusingly with the 

 foliage. In the case of the sparrows, which are 

 peculiarly ground-birds, it has been ingeni- 

 ously suggested that their prevailing neutral 

 colors prove them to be the ''survival of the 

 fittest" to escape the sharp eyes of their vari- 

 ous enemies, all the brighter-colored species (if 

 there ever were any) having been gradually 

 exterminated. 



In the construction of their nests, too, it is 

 often evident that birds feel the necessity of 



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