6 THOMAS SADLER ROBERTS 



the northern division of the Austral Region. Thus two of the 

 major biologic divisions of North America, the Boreal on the north 

 and the Austral on the south, come in contact diagonally across 

 the state of Minnesota. The Zones south of the Canadian are 

 subdivided into eastern and western portions, designated by 

 zoologists Faunal Areas, the chief determining factor being the 

 mean humidity. For example, the humid eastern portion of the 

 Transition Zone from the Great Plains to the Atlantic Coast is 

 called the Alleghanian Faunal Area, within which lies all of Minne- 

 sota not included in the Canadian. 



It is not of course to be understood that these various life 

 areas are separated from one another by well-defined lines. In- 

 stead, two contiguous areas blend into each other over a strip of 

 greater or lesser width, which presents intermingled characteristics 

 of each. 



On the western prairies of Minnesota are to be found a consid- 

 erable sprinkling of plants and animals from what was formerly 

 known as the Campestrian or Plains Flora and Fauna farther 

 west; and in the southeastern corner of the state occurs, as an 

 extension northward along the bottom-land of the Mississippi 

 River, a smaller representation from the Carolinian Flora and 

 Fauna of the Upper Austral Zone (the middle portion of the Austral 

 Region) belonging properly to the latitude of Iowa and Illinois. 

 But these intrusions from the west and south are hardly great 

 enough to give a dominant character to the areas where they 

 occur, and may be regarded simply as a sort of veil over the true 

 face of the country. To designate these slightly differentiated 

 life areas of the state and as expressing their incomplete character, 

 the terms Pseudo- Campestrian and Pseudo- Carolinian may, per- 

 haps, be convenient and have been so used on the Life-Zone Map 

 accompanying this paper. Between these modified areas and 

 south of the Canadian, is a great tract, left white on the map, 

 which is typical Alleghanian, at least so far as the birds are con- 

 cerned, except for the presence of the Western Meadowlark and 

 scattered colonies of Brewer's Blackbird, western species that have 

 invaded this region. 



Western Birds Breeding in the Pseudo- Campestrian or Prairie 

 Region of Minnesota hut Not Regularly Elsewhere in the State 



Western Grebe, Eared Grebe, Swainson's Hawk, Burrowing 

 Owl, Arkansas Kingbird, Brewer's Blackbird (isolated colonies 



