How to Name the Birds 127 



brightly colored birds, there is marked sexual and seasonal variation 

 among Warblers, the male being the brighter in the spring, but 

 often resembling his mate in the fall, when the young bird of the year 

 may differ from both his parents. Thus, in making a ' key ' to our 

 thirty-eight eastern Warblers, the writer found it necessary to represent 

 their different plumages by somewhat over one hundred specimens. 



External Structure. — As in the case of color, Warblers vary so in 

 form that no one description can be given of the family as a whole. 

 The slender-billed species, well represented by the members of the 

 genus Helminthophila and Dendroica, might be confused with the Vireos, 

 but the bill is more acute and is never distinctly hooked. The flat- 

 billed, fly-catching species of the genera Wilsonia and Setophaga might, 

 if the bill alone is considered, be mistaken for true Flycatchers, from 

 which, however, aside from other reasons, they are to be distinguished 

 by their brighter colors. All Warblers have the back of the tarsus thin, 

 not rounded, as in the Flycatchers, and the three outer primaries of 

 nearly equal length. 



Appearance and Habits. — As might be expected, striking differences 

 in form are accompanied by striking differences in habit. Even among 

 the slender-billed Warblers, some haunt the bushes and some the trees, 

 and several may be called terrestrial. The flat -billed species, as has been 

 remarked, are Flycatchers, not, however, of the sedate, automatic, Phoebe 

 type, but of more erratic movement, while the majority are active flut- 

 tered — the feathered embodiment of perpetual motion. 



Song. — With some marked exceptions, notably in the genera Geotb- 

 lypis and Seiurus, the songs of Warblers are rather weak and character- 

 less, and bear a resemblance to one another, which renders them of little 

 assistance to the beginner in identifying their owners. Indeed, com- 

 paratively few field -students can distinguish at once the notes of certain 

 species. Particularly is this true of migrants, which, present only for a 

 brief period in the spring and songless when returning in the fall, are 

 heard, therefore, at intervals of nearly a year. 



Family 13. Pipits and Wagtails. Motaciltida. 



Range. — Of the sixty odd species included in this family, only three 

 are American, two being North, one South American, while the remain- 

 der are distributed through the Old World, except in Polynesia and Aus- 

 tralia. The only species found regularly east of the Mississippi is the 

 American Pipit or Titlark. 



Season. — The Titlark breeds in arctic and subarctic America and 

 southward in the higher parts of the Rocky mountains. It winters from 

 the southern states to Central America, migrating in October and April. 



