68 Seton, Bird Records from Great Slave Lake. [^ail^ 



by one or two feathers only. This, therefore, is comparable to the 

 condition in specimen No. 3 which shows black on one side only 

 of the throat. 



In the Golden-winged Warbler the early white-throated stage has, 

 on this theory, been skipped in the normal bird, for the young have 

 the dark throats of their parents. Brewster's Warbler with its 

 white throat would then be an instance where the hypothetical 

 ancestral stage has not been skipped. It is possible that some of 

 these white-throated birds, if allowed to live, might ultimately 

 develop black throats. 



I wish here to express my indebtedness to Dr. Walter Faxon 

 for assistance in the elaboration of this paper, and I would draw 

 the following conclusions : 



That Brewster's Warbler is not a leucochroic phase of the Blue- 

 winged Warbler, but that it is either (1) a hybrid between the 

 Golden-winged and the Blue-winged Warbler«, or (2) that, in the 

 white-throated form, it is a phase, ancestral in character, of the 

 Golden-winged Warbler, and that there is a complete series of 

 intergrades between this and the Blue-winged Warbler. 



BIRD RECORDS FROM GREAT SLAVE LAKE 

 REGION. 



A Preliminary List of Birds observed by my 1907 Expedition 

 INTO THE Arctic Barren-grounds of Canada.' 



BY ERNEST THOMPSON SETON. 



Common Loon. Gavia imber. Common throughout the whole region 

 from Fort Resolution to Back's River. Especially so on all the northern 

 lakes. This and all the Loons stay until frost drives them out in October. 



Yellow-billed Loon. Gavia adamsii. Common and generally dif- 

 fused from Fort Resolution to Alymer Lake. Its caten\'auls and yodels 

 are much like those of the Common Loon. 



Pacific Loon. Gavia pacifica. Pacific or White-headed Loon. Com- 

 mon everywhere from Fort Resolution to Aylmer Lake, but most abundant 

 on Great Slave Lake. 



iFor the identification of many species, chiefly the Gulls, I am indebted to Mr. E. 

 A. Preble. 



