PLUMAGE OF WARBLERS 9 



is unchanged until the succeeding spring when certain feathers of the 

 body may be changed, and, thereafter, this order of molt is apparently 

 followed by the species. 



Nestling Plumage. — It is difficult, if not impossible, to frame a 

 law which shall express the relations of the nestling plumage of 

 Warblers to their adult plumage. When, however, the adult is olive- 

 green above, yellow or whitish below and without spots or streaks, 

 the young is dull olive-green or olive-brown above, dusky olive or 

 grayish below with the belly whitish or yellowish. 



Examples are Helminthophila peregrina, H. rubricapilla, H. 

 pinus, Dendroica vigorsi, Geothlypis trichas, Oporomis formosa, 

 IVilsonia pusilla, W. mitrata, and Icteria virens. 



When the plumage of the adult is varied in pattern with streaks 

 or spots, etc., the plumage of the nestling, while it may be widely 

 different, is generally streaked or spotted. Examples are Mniotilta 

 varia, Dendroica coronata, D. auduboni, D. maculosa, D. striata, D. 

 castanea, D. blackbumice, D. palmarum, and the Seiuri. 



When the adult is gray above the nestling is gray, as in Helmin- 

 thophila lucice, Dendroica nigrescens, and D. dominica; and when the 

 adult is brown above the nestling is brown or brownish, as in Helinaia 

 swainsoni, Helmitheros vermivorus, and Seiurus aurocapillus. 



As might be expected, indications of common ancestry are betrayed 

 by the nestling plumage. The nestlings of Dendroica coronata and 

 D. auduboni, for instance, while quite unlike the nestling of any other 

 Warbler known to me, very closely resemble one another, and the 

 spotted nestlings of Dendroica striata and D. castanea are almost 

 indistinguishable. Among the more uniformly plumaged, olive-green 

 birds this similarity in the plumage of the nestling also prevails. 



An interesting character shown by the nestling, with but few 

 exceptions, is the presence of wing-bars when they are absent or 

 obscure in the adult. These bars are usually buff but are gen- 

 erally in strong contrast to the wing-coverts, of which they form the 

 tip. With the molt from nestling into first fall plumage, these coverts 

 are shed and the bars lost, a fact which suggests that the unbarred 

 wing represents a higher stage in the development of the species 

 than the barred wing. 



When, in the adults, there exists a sexual difference in the color 

 of the wings or tail, the nestling presents a corresponding difference 

 in color, since both wings and tail are retained until after the first 

 nesting season (e. g. Dendroica ccerulescens) . When, however, no 

 such difference exists, the nestlings of both sexes are alike in color. 



