OF KEW ENGLAND. 155 



simply constructed bill alone, to fashion a home for themselves, 

 pf which man with his complicatedly organized fingers, and 

 the aid of all his inventions, cannot (probably) make the 

 like ! It seems probable that instinct rather than any acquired 

 skill insures perfection (and yet it is perhaps true that many 

 birds have improved in architecture from generation to genera- 

 tion"^^). On the last day, the female is chiefly occupied in 

 smoothing and shaping the nest by turning round and round 

 inside, and then on the following day, or the next, begins to 

 lay her eggs. 



The Yellow-throated Vireos frequent the woods which are 

 lightly timbered with oaks, chestnuts, and maples, or even 

 pines, and also orchards. Among the branches of the trees 

 in these places they are almost continually moving in search 

 of caterpillars and other insect-food. 



(d). Their song lacks the expression of the Solitary, the 

 volubility of the Red-e3'ed, the quaintness of the "White-eyed, 

 and the tenderness of the Warbling Vireo's song, and yet, with 

 all these wants, is very charming. It is difficult to describe it 

 exactl}', but it consists of two or three warbled notes on an 

 ascending scale, and then, after a pause, others with a falling 

 accent, all being repeated disjointedly in a characteristic voice. 

 Their ordinary querulous note is distinct from that of the 

 "Red-eye," being somewhat harsher, and is often rapidly re- 

 peated. 



I may finally say of these birds whose biography I have just 

 written, that they are useful to the farmer and agriculturist, 

 and deserve on all accounts to be protected. 



(C) OLiVACEUS. Red-eyed Vireo. 



(A common summer-resident throughout New England.) 

 (a). About six inches long. Olive-green above (often of 

 quite an indescribable shade), becoming ashy on the crown, 

 which is bordered by a narrow black line. Superciliary line 



••lit is to be coiisiderecl that such improvement as is here refeiTCcI to arises from 

 adaptation to circumstances rather than from efforts to realize an ideal. 



