24 



NORTH AMERICAN FAUNA 73 



Table 2. Classification of wetland types in the St. Croix River Valley. This 

 classification follows Cowardin etal. (1979) and Curtis (1959). 



Wetland name 



Wetland type 







used in 



(Shaw and 



Water 





this report 



Fredine 1956) 



chemistry 



Authority 



Temporarily flooded 



1 



Fresh 



Cowardin et al. 



Northern sedge meadow 



2 



Fresh 



Curtis 



Seasonally flooded 



3 



Fresh 



Cowardin et al. 



Semipermanently flooded 



4 



Fresh 



Cowardin et al. 



Permanently flooded 



5 



Fresh 



Cowardin et al. 



Shrub carr 



6 



Fresh 



Curtis 



Bog 



8 



Acidic 



Curtis 



Nomenclature 



The taxonomic treatment of birds presented in this report follows the 

 American Ornithologists' Union (AOU) Check-list of North American Birds 

 (1957), and the 32nd (AOU 1973) and 33rd (AOU 1976) supplements to the 

 Check-list. One deviation from the AOU standard sequence is presented for 

 the shorebirds. In this instance, I followed the sequence recommended by 

 Jehl(1968). 



Description of the major plant communities of the Valley follows Curtis 

 (1959). Major habitats used by each species were determined from personal 

 field investigations and from published reports. The taxonomic names of 

 plants described in the habitat sections are those used in Gleason and Cron- 

 quist (1956). Common names of some plant species, primarily grasses and 

 sedges, are taken from Britton and Brown (1913). Voucher specimens of 

 most of the important grasses and forbs used in this report are housed in the 

 Herbarium, Department of Biology, University of Wisconsin— River Falls. 



The wetland classification used in this report (Table 2) is a combination of 

 the systems developed by Cowardin et al. (1979) and Curtis (1959). Cowardin 

 et al. (1979) employ a hierarchical system with modifiers for water regime, 

 water chemistry, and soil type. Three wetland types (Northern Sedge 

 Meadow, Shrub Carr, and Bogs) were named and classified by Curtis (1959). 

 Because these names are widely used and accepted in the Valley, I have 

 deviated from Cowardin 's system in that instance. 



Species Accounts 



FAMILY GAVIIDAE: Loons 



Common Loon {Gavia immer) 



Status: Regular migrant and nesting species. 



Migration: Common (locally abundant) during spring and fall throughout 

 the Valley. Spring migrants arrive in the Western Upland during the first 



