RRFAVSTER'S WARBLER. 313 



est the srowtli of the young of this pair in their slow progress from tlie nesthng 

 plumage to the first winter ])lumage. When first seen, on the 15th of June, 

 these young birds were probably not more than two days out of the nest, and 

 both Dr. Tyler and myself saw, or thought we saw, a deeper yellow tint on 

 their breasts and bellies than we had hitherto seen on young chrysopterae and 

 leucobronchiales of the same age; by the 20th of June, however, this yellow 

 tinge was much less pronounced, and by the 25th of the month, when the tails 

 of the little birds were about three quarters of their full length, the yellow was 

 scarcely apparent, the young still wearing the juvenile dress. Dr. Tyler had 

 fastened a platinum band on the leg of one of the little birds of this family on 

 the^ 15th of June; we were thus enabled to note the change of color in the same 

 individual as the days wore on, — a change doubtless due to the loss of the 

 fugacious, veiling, yellow tips of the juvenile feathers. 



On the 27th of June we saw the first signs of the post-juvenile moult in 

 the loss of one set of wing-coverts with its yellowish bar. By the first of July 

 the contour feathers of the juvenile plumage were being extensively replaced 

 by those of the first winter plumage. As in former seasons (1910, 1911) amarked 

 difference was apparent in the amount of yellow on the under parts of the dif- 

 ferent indivitluals of the same brood. In at least one of the brood now under 

 consideration the yellow tint was very faint and it was clear even at this early 

 date that this young one was a leucobronchialis ; in other members of this same 

 brood the second winter plumage displayed a strong yellow tint on the throat 

 and along each side of the breast and belly, following the area of the ptcryla 

 vrntralis and leaving an ash-colored longitudinal band along the median line 

 of the abdomen, caused by the retention of some of the juvenile set of feathers. 

 As time went on, the yellow color gradually became fainter and restricted for 

 the most part to the breast, leaving the throat and abdomen ashy white; the 

 growth of a black trans-ocular stripe and yellow wing-coverts now perfected 

 the garb of Hclminlhophila leucobronchialis. On the 12th of July at least two of 

 this brood of young birds were as slightly tinged with yellow as the young 

 leucobronchialis figured on the plate of my memoir of 1911 (fig. 1). Not one 

 of this brood developed the least trace of the black throat and broad cheek- 

 patch of H. chrysoptera. 



As I have previously said, the varying amount of yellow, at the same date, 

 in different young Brewster's Warblers of the same brood was noticeable in 

 all of tlic years in which we observed the growth of the winter plumage in these 

 birds. This may be the result of different degrees of precocity in the individ- 



