210 BIRDS OF PENNSYLVANIA. 



ular and tolerably common winter resident from November to April, 

 frequenting briery thickets, thorn hedges and grassy fields near trees 

 and bushes. They sometimes visit towns and prey on English Spar- 

 rows. The name of Butcherbird given to members of this genue, 

 arises from the habit they frequently have of impaling their prey on 

 thorns, or sharp-pointed twigs, etc. Shrikes feed chiefly on grass- 

 hoppers and beetles, and when these are not easily obtained they sub- 

 sist on mice and small birds. The Northern Shrike, assassin-like, will 

 conceal himself in bushes and imitate the cries of other birds, and 

 when they come sufficiently near his ambush he will, to their great 

 consternation, fly into their midst and seize one of their number. 



FAMILY VIREONID-ffl VIREOS. 



[NOTE. The Vireos have the wings pointed or rounded, and equal to or longer 

 than the even or rounded tail. "Primaries apparently only nine, the first being 

 rudimentary or displaced (occasionally quite visible"). The feathers of the upper 

 parts are greenish-olive, of different shades ; lower parts whitish or yellowish or 

 both ;" eyes brown, except in the Red and White-eyed species, and even the young 

 of these have brown irides. These birds frequent chiefly woods and thickets, yet 

 some, particularly the Red-eyed and Warbling, are common during migrations about 

 yards and gardens in towns. Both of these species also often breed in the trees of 

 parks and gardens. The Vireos are rather plainly attired, and were it not for their 

 delightful and mtfsical notes, they would much oftener escape our notice than they 

 do ; few of our woods birds are equal to them as songsters. They live almost con- 

 stantly in the leafy retreats of trees and shrubbery, rarely, if ever, do they rest on 

 the ground. They subsist almost exclusively on insects, chief among which may be 

 mentioned flies, spiders, beetles and various larvae ; in the late summer and autumn 

 some species feed to a small extent on a few kinds of berries. We have in Pennsyl- 

 vania six species, viz : the Red-eyed, Warbling, Blue-headed, Yellow-throated, 

 White-eyed and Philadelphia Vireos, and all with the exception of the Philadelphia 

 Vireo, are common as summer residents or spring and fall migrants. Their beauti- 

 ful cup-shaped, or basket-like and pendulous nests, are composed of pieces of bark, 

 lichens, rootlets, fine grass stems, bits of paper, etc., and suspended from forked 

 twigs. Vireos nest in trees and bushes, usually in groves or forests ; some build 

 close to the ground ; others erect their pensile homes on the highest twigs of tall 

 forest trees. Their elongate-ovate eggs, commonly five, are white, thinly speckled 

 or dotted, usually about the larger end with black or brown. They measure gener- 

 ally a little more than of an inch long, by \ an inch wide. The Red and White- 

 eyed Vireos breed very abundantly with us, and in a large proportion of their nest c , 

 especially in nests of the Red-eyed species, you will find Cowbirds' eggs or young 1 . ] 



GENUS VIREO. VIEILLOT. 

 624. Vireo olivaceus (LINN.). 



DESCRIPTION (Plate 40. Adult male). 



Largest of the genus. Length about 6|, extent about 10^ inches ; bill blackish 

 above, below bluish-white ; feet and legs lead color ; iris red ; back, rump, upper 

 parts of wing and tail feathers olive-green ; sides of head and neck paler ; crown 

 dark-ash, edged with a blackish line ; a well-defined whitish line from nostril over 

 the eye and back of it ; a dusky stripe through the eye ; under parts white, shaded 



