BLACK-POLLED WARBLER 399 



and black and white plumage are assumed, at first evidently, somewhat veiled 

 by whitish edgings. 



Adult winter plumage acquired by a complete postnuptial moult in July. 

 Similar to first winter dress but whiter below, the streaking often distinctly 

 black and extending to the chin, which is spotted here and there ; above the crown 

 is decidedly streaked or marked with stray black feathers ; the wings and tail are 

 blacker and the edgings are darker and grayer especially on the tertiaries. The 

 slight sprinkling of black feathers is like that found in Dolichonyx orizivorug 

 and some other species in the autumn. 



[Female] * * * plumages and moults correspond to those of the male, 

 from which it is first distinguishable in first winter plumage, but not in every 

 case. Females are then a little greener above and yellower below including the 

 crissum, the streaks on the side extremely faint. The first nuptial plumage 

 acquired by moult is a little paler than the first winter, the head, back and sides 

 with distinct black streaks ; resembles the male in first winter dress but more 

 decidedly streaked. The adult winter plumage is practically indistinguishable 

 from the first winter but rather paler and with the wing edgings darker. The 

 adult nuptial plumage much resembles the male in adult winter dress and is 

 merely tinged with yellow and streaked on crown, back, sides of chin, and sides 

 with black. The black cap and broad streaking of the male are never acquired. 



The fall or winter plumage of the blackpoll is so similar to the first 

 winter plumage of the bay -breasted warbler that even the most experi- 

 enced field observers find them extremely difficult to differentiate 

 during the fall migration. This confusion has often lead to erroi-s in 

 field identification, so that reports of the relative abundance and dis- 

 tribution of these two species during the fall migration are sometimes 

 confusing. 



The upper parts of the blackpoll are duller and more streaked, the 

 wings are edged with a yellow-green in place of gray-green ; the under- 

 parts are yellowish instead of buffy. These differences are not con- 

 stant, and some individuals of the bay-breasted warbler can be dis- 

 tinguished only by the trace of chestnut on the flanks and under tail 

 coverts. Perhaps the best field mark is the color of the legs, which in 

 the blackpoll is light, approaching a yellowish, while in the bay- 

 breasted warbler it is dark brown and in some instances almost black. 

 It is true these warblers are more deliberate in their movements, offer- 

 ing better opportunities for detailed observation, but even so, positive 

 identifications are often impossible in the field. 



Concerning the post] u venal molt and the acquiring of the fall or 

 winter plumage E. A. Preble (1908) writes of blackpoll warblers 

 observed and collected in the Mackenzie region of northwest Canada. 



The blackpoll occurs in summer throughout the region north to the very 

 edge of the wooded country. It arrives on its breeding ground late in May, 

 and some individuals are on their way south again in late July, molting as they 

 travel, into the olivaceous plumage common to old and young in autumn. * * * 

 Birds of the year taken July 19, 23, and 29 are in the spotted juvenal plumage, 

 but with the yellowish-green of the fall plumage [first winter] appearing on 

 the back, throat, chest, and sides ; the change was about half completed in most 



