SPECIES: 



All species found nesting in 1977 and their estimated numbers in each of the 10 States are reported in 

 Table 1. 



DATE: 



The month and day arc listed for estimates based on a single inventory. When two or more inventories 

 were taken, only that estimate judged to be the most accurate is listed. When the results from more than 

 one inventory are combined to provide an estimate, only the month is listed. 



INVENTORY METHOD: 



One purpose of the inventory was to determine the number of breeding pairs of each species at each 

 colony site-. Methods used to obtain the figures in the study arc listed. They included: 1) total counts oi 

 nests (most reliable) or adults; 2) aerial estimates of cither the adults present or nests; 3) counts from aerial 

 photos; or 4) counts in sample portions of colonics. At many colonies more than one method was used to 

 derive the final estimate. 



For most colonics, southern Maine to Virginia, the inventory data are based on aerial estimates of adults. 

 Nest counts were made at selected colonies in this region and were used to calculate the correction factors 

 which were applied to aerial estimates for some species (Erwin 1979). 



In northern Maine, most colonies were ground-checked and counts oi nests or adults were made to 

 determine the number of nesting pairs for each species. For more detail on inventory methods for each 

 region (northern Maine, southern Maine to Virginia), the reader is referred to each of the final reports 

 (Korschgen 1979, Erwin 1979, respectively). 



NUMBER OF BREEDING PAIRS: 



Only the best estimate for each species at a colony site is given. No adjustment is made for nesting starts 

 that may have been terminated prior to the inventory, or initiated afterwards. For a few colonies at which 

 no inventories were conducted in 1977, data from 1976 have been used. 



