7.20 Riioads on the Hndsonian Chickadee and its Allies. Q " t 



ungava, representing the faunal peculiarities of northern Labrador 

 and Newfoundland. 



Geographic and climatic conditions in North America north of 

 the United States result in a primary division of the country into 

 two great life areas, the Temperate and the Arctic. Of these the 

 Hudsonian Chickadee inhabits the southern border of the Arctic 

 Realm and that part of the Temperate defined by Dr. Allen as 

 the Cold Temperate Subregion, or the 'Boreal' of Dr. Merriam's 

 faunal maps. 



The Arctic Realm includes that part of the known habitat of 

 hudsonicus from which were procured the types of Mr. 

 Ridgvvay's P. h. stoneyi and my P. h. ungava. This district 

 may be defined as a strip of varying width reaching along the 

 Alaskan coasts and peninsulas of Bering Sea and the Arctic 

 Ocean to the mouth of the Mackenzie River, thence to the mouth 

 of the Nelson River and northward, including the north coasts of 

 Labrador and Newfoundland. The Cold Temperate Subregion 

 includes the type localities of P. hudsonicus, P. h. cvura, P. h. 

 littoralis, and P. h. columbianus and covers the remaining area 

 of distribution of the group southward. 



In the cases of ungava and stoneyi we have two races occupy- 

 ing very similar environments of minimum temperature and 

 diminished flora but of differing humidity, and in all probability 

 separated by a vast central area of the Barren Ground Fauna in 

 which hudsonicus has no representative because of the almost 

 total absence of trees in those regions. In columbianus we have 

 another example of the maximum development of western races 

 which, as in evura. Alaskan forms are sure to show, and in 

 which the size generally increases as the habitat approaches the 

 forty-ninth parallel. 



Limiting ourselves to resident species of boreal North America, 

 which show a tendency to split up into races, we quite invariably 

 find the largest and darkest colored races in the southwest, either 

 on the west slopes of the Rockies or in the West-Cascade region. 

 The smallest light-colored forms hail from central and southeast- 

 ern districts, while the extreme northwest and northeast produce 

 forms of an intermediate character between the Rocky Mountain 

 and Atlantic Coast races, the Labrador race being darker and 

 somewhat smaller than its Alaskan counterparts, but not so dark 



