BREWSTER’S WARBLER. 67 
birds of the earliest brood left the nest, June 17, to the 20th of July when the 
opportunities for observing were lost on account of the dispersal of the families 
is a period of 34 days. I devoted a portion of twenty-four of these, amounting 
altogether to upwards of 75 hours, to the study of these birds. If now it be 
borne in mind that for a month or more after leaving the nest the young are 
constantly fed by the parents and most assiduously by the male, the inference 
that the male leucobronchialis was unmated is irresistible. That there was but 
one chrysoptera in the second brood observed is not so certain, but probable in 
the highest degree. At all events a large majority of this brood were leuco- 
bronchiales. 
Since Helminthophila leucobronchialis was first described by Mr. Brewster 
in 1874, almost every conceivable hypothesis has been advanced by one writer 
or another to fix its true status in our bird-fauna. And yet it remains one of 
the most perplexing of ornithological problems. It was at first treated as a 
valid species, but its rarity, its association with H. pinus or H. chrysoptera, 
its intergradation with one or the other of these species, especially the former, 
by a series of intermediate forms, the peculiarity of its distribution, and the fact 
that it possesses no peculiar characters which are not found in either one or the 
other of the two species mentioned, led soon and inevitably to the theory that 
it is nothing else than a hybrid produced by the union of H. pinus and H. chryso- 
ptera. Mr. Brewster himself was one of the earliest advocates of this theory 
and he has consistently adhered to it up to the present time. In the Bulletin 
of the Nuttall Ornithological Club, 1881, 6, p. 218-225, he gave his reasons 
for thinking that H. leucobronchialis and H. lawrencei both were hybrids of H. 
pinus and H. chrysoptera, the two forms being produced by a reversal of the 
sexes In crossing, like the mule and the hinny. 
In the Auk, 1885, 2, p. 359-3863, Mr. Ridgway while admitting lawrencei 
to be a hybrid between pinus and chrysoptera held to the view that leucobron- 
chialis was a distinct species, which by interbreeding with pinus produced the 
various intermediate stages connecting leucobronchialis with pinus, and by 
interbreeding with chrysoptera produced the extremely rare forms which com- 
bine characters of leucobronchialis and chrysoptera. A few years later (Manual 
N. A. Birds, 1887, p. 486), Mr. Ridgway deemed it more likely that leuco- 
1 Mr. Ridgway, Dr. Bishop, and Mr. Chapman have maintained that the white throat of Brewster’s 
Warbler is a peculiar character not found in either the Blue-winged or the Golden-winged Warbler. Al- 
though this is technically true it does not seem to me to bear against the theory that Brewster’s is a 
hybrid between the Blue-winged and the Golden-winged Warblers. If the Golden-wing transmitted 
the white ground color of the lower parts without transmitting the black throat one would expect the 
hybrid to have a white throat. 
