VIREOS. 159 



(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 architec- 

 ture from generation to generations^). 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 volu- 

 bility of the Red-eyed, 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 exactly, 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 i-epeated 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 agricul- 

 turist, 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, 

 white ; eye-stripe, dusky. Under parts, white ; sides olive- 

 shaded. Wings and tail, generally dusky. Iris, red. 



b. The nest is hung from a fork, usually near the end of 



''^ It is to be considered that such im- distribution and exceeding abundance, 



provement as is here referred to arises found throughout New England wher- 



from adaptation to circumstances rather ever there are woods, groves, orchards, 



than from efforts to realize an ideal. or even only scattered shade trees. — 



* A summer resident of ubiquitous W. B. 



