REMARKS ON FAMILY PARULIDAE 3 



The status of Vermivora leucohronchialis and V. lawrencii and 

 the relationship between them puzzled ornithologists for upward of 

 two generations. William Brewster (1876) described the former as 

 a new species, and since that time, as Walter Faxon (1911) writes, 

 "almost every conceivable hypothesis has been advanced by one writer 

 or another to fix its true status in our bird-fauna." In addition to 

 being considered a valid species, it has been regarded as a hybrid 

 (Brewster, 1881), as a dichromatic phase, that is, a leucochroic phase 

 of V. pinus (Ridgway, 1887), as a mutant (Scott, 1905), and finally as 

 a phase, "ancestral in character" (atavistic) of the goldenwing (C. W. 

 Townsend, 1908). 



Lawrence's warbler is a very rare bird. The first specimen was de- 

 scribed in 1874 (Herold Herrick, 1874), and since that time the bird 

 was taken or seen infrequently, chiefly in regions where the breeding 

 ranges of F. chrysoptera and V. pinus overlap. Consensus of opinion 

 in the main regarded it as a hybrid between V. chrysoptera and F. 

 pinus, as it combined characters of both the supposed parents. John 

 Treadwell Nichols (1908) some years ago brought new light to thw 

 problem. He says : 



In any discussion of the status of Lawrence's and Brewster's Warblers it is 

 well to bear in mind the facts, including the much greater abundance of Brew- 

 ster's, are in accord with Mendel's Law of Heredity, supposing both forms to be 

 hybrids between nelminthophila pititis and H. chrysoptera. * * * All the 

 first generation hybrids will be Brewster's Warbler in plumage. In the next 

 generation there will be pure Golden-winged Warblers, pure Blue-winged 

 Warblers, pure Brewster's Warblers, and pure Lawrence's Warblers ; also mixed 

 birds of the first three forms, but none of the last form, which, being recessive, 

 comes to light only when pure. The original hybrids then (which will be all 

 Brewster's in plumage) must be fertile with one another or with the parent 

 species for any Lawrence's to occur ; and if they are perfectly fertile Lawrence's 

 must still remain a small minority. After the first generation the proportion 

 of plumages of birds with mixed parentage should be : 9 Brewster's, 3 chrysop- 

 tera, 3 pinus, 1 Lawrence's. 



This explanation removed the stumbling block, long believed to be 

 insurmountable, that a black-throated bird, mating with a yellow- 

 throated bird, could produce progeny having a white throat. Under 

 Mendel's Law the dominant color (white) of chrysoptera would ap- 

 pear by the suppression of the recessive black throat. 



Fortunately, Walter Faxon (1913) not long afterward found a fe- 

 male blue- winged warbler mated with a goldenwing and was success- 

 ful in following the resulting brood of young birds until they had 

 acquired their first winter plumage when, fulfilling Mendel's Law, 

 they were all in "the garb of Ilelminthophila leucohronchialis,^^ thus 

 establishing beyond a doubt the hybrid nature of the bird. At the end 

 of his paper, Walter Faxon (1913) relates a bit of interesting ancient 

 history regarding these three species of Vermi'vora. He says : 



