72 BREWSTER'S WARBLER. 



a Golden-wing.' When one considers the number of Brewster's Warblers that 

 have been found in certain parts of Connecticut, these misalliances can hardly 

 be attributed to accident. They go to make a strong case against the theory 

 that Brewster's Warbler is a valid species. So, too, the state of affairs disclosed 

 in the Lexington swamp, where a beautiful male Brewster's Warbler failed to 

 secure a mate while two female Brewster's Warblers mated with Golden-wings. 

 This bears with ecjual weight, moreover, against the view that Brewster's Warbler 

 is a color-phase of the Blue-wing, a view that implies the failure of the male 

 to secure a mate although competing with males of another species. Why, 

 furthermore, if leucobronchialis be an albinistic form of pinus should the white 

 wing-bars of pinus be transformed into the yellow wing-bars of leucobronchialis? 



Dr. Townsend's suggestion that leucobronchialis may be a dimorphic form 

 of chrysoptera is opposed to the fact that the former is rarely found where the 

 latter is a common bird, but usually where pinus is common, and where the 

 distributional areas of pinus and chrysoptera meet. 



To the hypothesis that Brewster's Warbler is a hybrid .resulting from the 

 union of the Blue-wing and the Golden-wing I can see no objections. A very 

 large majority of the specimens of Brewster's Warbler that have been discovered 

 have been found in regions like the State of Connecticut where the ranges of 

 the Blue-wing and the Golden-wing overlap. The sporadic appearance of 

 leucobronchialis in a region like Eastern Massachusetts is amply accounted for 

 by the occasional occurrence of pinus in the same region. 



In a suggestive note published in the Auk, 1908, 25, p. 86, Mr. J. T. Nichols 

 shows that in case of a union of H. pinus with H. chrysoptera, if we assume that 

 the white ventral color of chrysoptera and the plain throat of pinus play the part 

 of dominants in transmission, by Mendel's Law of Heredity the offspring, Fi, 

 should all be Brewster's Warblers in plumage. ^Adopting Mr. Nichols's system 

 of symbols, let W stand for the dominant white under parts of chrysoptera, 

 w for the recessive yellow of pinus; let P stand for the dominant plain throat 

 of pinus, while p represents the recessive black throat of chrysoptera. Then : 



 Mr. C. J. Maynard (Warblers of New England, Addenda, 190S, p. 139-140; Record of Walks and 

 Talks, 1908, 1, p. 79) and Mrs. J. W. Sherman (Auk, 1910, 27, p. 444) by some strange vagary have 

 identified the mates of the male Brewster's Warblers that bred in the Arnold Arboretum, Jamaica Plain, 

 Mass., in the summers of 1907 and 1908, as female Brewster's Warblers. They were in reality Golden- 

 winged Warblers in very high plumage, the throat patch being uncommonly dark for the female, and 

 the upper border of the ash-colorcd cheek patch deepened into a dusky hue. Mrs. Sherman has added 

 to the confusion by publishing in the Auk, 1910, 27, p. 44.3-447, an account of a pair of Golden- 

 winged Warblers found breeding in Roslindale, Mass., in June, 1910, which .she was deluded into be- 

 lieving to be a male Golden-wing and a female Brewster's Warbler! A female Brewster's Warbler does 

 not have a dusky nor a gray throat patch, neither does it have a gray cheek. 



