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 Mniotiltidce) like the Vireos are distinctly 

 American birds, indeed they may be called characteristic North Amer- 

 ican 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 Seiurus}. 

 Insects constitute almost their entire fare and they are among our 

 most beneficial birds. 



Most of the Wagtails (Family Motacillida) , are inhabitants of the 



167 



