BRE WS^n<; R S WAR B LER ( HELMINTIIOI'IIILA L E U( 'OBlxONCHIA- 

 LIS) A HYBRID BETWEEN THJ-: GOLDEN-WINGED WARBLER 

 (HELMINTHOPHILA CHRY SOFT ERA) AND Tim BLUE- 

 WINGED WARBLER {HELMINTHOPHILA PINUS). 



The real nature of Brewster's Warl)lcr lias long been a moot point with 

 ornithologists. Is it a true species, a mongrel, a color-phase of the Blue-winged 

 Warbler, or an atavistic form of the Golden-winged Warbler? Each of the four 

 propositions implied in this question has found advocates among the various 

 authors who have written on the topic, but until now no indubitable proof of 

 the true status of this bird has been obtained. 



In Januarv, 1911,1 published a paper bearing on this subject, in the Memou-s 

 of the Museum of Comparative Zoology, 40, no. 2; I will here give a resume 

 of the facts recorded in it, a course which seems desirable because these facts 

 were misstated by the reviewer of my article, in The Auk for April, 1911. 



In the summer of 1910, there bred within the confines of a swamp of about 

 fifteen acres in Lexington, Mass., a pair of Golden-winged Warblers, and two 

 male Golden-winged Warblers mated with two female Brewster's Warblers. 

 In the same swamp there was also a male Brewster's Warbler that unquestion- 

 ably was unmated. The progeny of the three pairs were closely observed from 

 the juvenile (in one case, from the natal) plumage up to tlie first winter plumage, 

 when the adult characters were acquired; the young of the pair of Golden-wings 

 were all Golden-wings; one of the Brewster's W'arblers that was mated witli a 

 Golden-wing brought forth a homogeneous brood of Brewster's Warblers, while 

 the other produced a mixed brood of Brewster's Warblers and at least one Golden- 

 winged Warbler. A striking thing about it was this : the j'oung birds of mixed 

 parentage were absolutely pure in plumage, — either Brewster's Warblers or 

 Golden-wings, without any tendency to combine, as "intermediates," the char- 

 acters of the two parents. They appeared to exemplify the transmission of 

 characters in accordance with JNIendel's Law, and from that time I had little 

 doubt that Brewster's Warbler itself would pr()\e to be a result of the union 



