BIRDS OF THE ST. CROIX RIVER VALLEY 5 



Fig, 1. The St. Croix River watershed, including Minnesota and Wisconsin, encom- 

 passes nearly 11,550 km^ 



18 counties, 9 in each State (Fig. 1). There are eight major streams or water- 

 sheds that are tributary to the St. Croix, including the Snake and Kettle 

 rivers, and Pine County streams in Minnesota (Waters 1977), and the Name- 

 kagon. Clam, Apple, Willow, and Kinnickinnic rivers in Wisconsin. 



Related to the tremendous amount of diversity and variability in the 

 topography and geology of the St. Croix River Valley, various geographers 

 and plant ecologists have developed systems for classifying landforms and 

 major vegetative communities (Fig. 2). These systems have provided divi- 

 sions that are important in understanding the interrelation of bird distribu- 

 tion with vegetation and geomorphic features. Two separate systems have 

 been developed, one for each State. Both systems have considerable merit 

 considering the foundation upon which they were based. Unfortunately, 

 these separate systems make interpretation of bird distribution awkward 

 when considering the two States. Following is a brief overview of these 



