PERCHING BIRDS. 
They search the foliage carefully for leaf-eating insects and their 
eggs, and examine the crevices in the bark for eggs of the injurious 
wood-boring insects. They are therefore unusually beneficial birds. 
Bearing a general resemblance in size and color to many of the 
Warblers, Vireos are sometimes confused with members of that family. 
They are, however, as a rule, more deliberate in their motions and not 
such active flutterers as are many of the Warblers. They are also 
more musical, all the Vireos having characteristic songs, which if not 
always highly musical, are generally noticeable, pronounced and unmis- 
takable. 
The nests of all our Vireos are pendant, deeply cup-shaped struct- 
ures usually hung between the forks of a crotch, to the arms of which 
they are most skilfully woven. 
The Warblers, (Family MZniotil/tidg) like the Vireos are distinctly 
American birds, indeed they may be called characteristic North Amer- 
ica birds since most of the one hundred odd species are found north of 
Mexico. Between thirty and forty species of these active, beautiful 
little creatures may be found in the course of a year at a single local- 
ity in the Eastern States and they therefore constitute an exceedingly 
important element in our bird-life. Most of them come in May at, the 
height of the spring migration, when the woods often swarm with them 
as they flit from limb to limb in pursuit of their insect food. The larg- 
er number of them pass onward to their northern homes and in Sep- 
tember they return to us in increased numbers. 
The beauty of their plumage, the briefness but regularity of their 
visits, the rarity of certain species, combine to make the Warblers es- 
* pecially attractive to the field student and their charms are heightened 
by the difficulty with which many of them are identified. Study them 
as we may there are still species which have escaped us. 
By far the larger number of Warblers may be described as flutterers 
that feed agilely about the terminal branches, (genera Dendroica and 
Helminthophila); others are true flycatchers, so far as feeding habit is 
concerned, (genera Setophaga and Wilsonia,) while others still feed in 
the undergrowth or on the ground, (genera Geothlypis and Seturus). 
Insects constitute almost their entire fare and they are among our 
most beneficial birds. 
Most of the Wagtails (Family Motacillidz), are inhabitants of the 
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