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 Hehninthophila 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 j-et 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. 359-363, 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 intermediat^e 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- 



' Mr. Ridgway, Dr. Bishop, and Mr. Chapman have maintained that the white throat of Brewster's 

 Warbler is a pecuhar 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. 



