68 Tue Birps Asout Us. 
enable the observer to guess pretty shrewdly, par- 
ticularly if the bird in question is in the tree-tops 
singing loudly, even vociferously, and often launch- 
ing out like a pewee to catch some passing insect. 
There are three that are found here in the Middle 
States abundantly,—the Red-eyed, the White-eyed, 
and the Warbling Vireo. Warren, in “ Birds of Penn- 
sylvania,” says that the Yellow-throated Vireo “breeds 
sparingly or irregularly in nearly all sections of the 
State, but is apparently much more frequently met 
with in the mountainous and elevated woodland 
regions, particularly in the northern counties, than 
elsewhere as a summer resident.” Like many an- 
other insect-feeder, they can take to a vegetarian diet 
when necessity calls, and this, I think, explains why 
the date of departure in autumn is so irregular. 
Certain it is that the low-lying land along the tide- 
water reaches of the river does not yield to winter’s 
onslaught as does the hilly back country, and here 
birds congregate and sometimes remain all winter. 
The cat-bird and some warblers remain; the che- 
wink and several water-birds find a sufficient food- 
supply ; and what I have always insisted upon was a 
closer inspection of some bird-full localities that 
ornithologists have persistently ignored. Warren’s 
“ Birds of Pennsylvania” gives a considerable num- 
ber of birds as breeding within the limits of that 
State not accredited to it in the general ornitholo- 
gies of the continent. 
The Red-eyed Vireo comes to the Middle States 
early in April, if the weather proves mild, and re- 
mains until the middle of October. In the autumn 
