20 



NORTH AMERICAN FAUNA 73 



Fig. 4. Location of Breeding Bird Survey routes in the St. Croix River Valley. 



counted for a sufficient number of years to allow meaningful comparisons. 

 Terms 



Considerable conjecture and argument has developed about what is the 

 best method for describing a species occurrence, regularity, and abundance. 

 Terms are treated under three categories: status, season, and abundance. 

 The terms used to describe each species status in the present report are 

 adapted from those presented in Green and Janssen (1975), including 

 Regular— A species that occurs at some location in the Valley during at 



least one season each year. 

 Casual— A species expected to occur at least once every 3 to 5 years, but 

 not annually. 



