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 equal 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 lewcobronchialis 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 lewcobronchialis 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, Fy, 
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: 
1 Mr. C. J. Maynard (Warblers of New England, Addenda, 1908, 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-colored cheek patch deepened into a dusky hue. Mrs.’Sherman has added 
to the confusion by publishing in the Auk, 1910, 27, p. 443-447, 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. 
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