210 Birds of Pennsylvania. 



iilar and toleral)ly conunou winter resident from November to April, 

 rre([uenting briery thickets, thorn hedges and grassy fields near trees 

 and bushes. They sometimes vi^r towns and prey on English Spar- 

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

 arises from the habit the}^ frequently have of impaling their prey on 

 thorns, or sharp-pointed twigs, etc. Shrikes feed chielly 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 

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

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



Family VIREONID^ Vireos. 



[Note. — Tho Vireos have the Avnigs pointed or rounded, and equal to or longer 

 than the even or rounded tail. "Primaries apparently'' only nine, tlio 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 iridcs. These birds frequent chielly woods and thickets, yet 

 some, particularly the Red-eyed and Warl>ling, are common during migrations about 

 yards and gardens iu 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 musical notes, tliey Avould iiuu-h oftener escape our notice than they 

 do ; few of our woods birds are equal to tliem 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 vax-ious larvte ; iu 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-ej^ed, Warbling, Blue-headed, Yellow-throated, 

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

 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 J of an inch long, bj- i an inch wide. The Red and Wliitc. 

 eyed Vireos breed very abundantly witli us, and in a large proportion of their nest«, 

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



Genus VIREO. Vieillot. 

 62-1:. Vireo olivaceus (Linn.). 



Dksckiptiox (Plate ^0. Adult ina In). 



Largest of the genus. Length about 0{, extent about lOj 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 wliitish line from nostril over 

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



