OF NEW ENGLAND. 155 
simply constructed bill alone, to fashion a home for themselves, 
of 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-eyed, the quaintnéss 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 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) oxrvaceus. 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 
41It is to be considered that such improvement as is here referred to arises from 
adaptation to circumstances rather than from efforts to realize an ideal. 
