Table 26. Factors used to convert aerial estimates of adults 

 into numbers of breeding pairs (nests) in a colony. 



Species 



Location 



Correction factor'^ 

 (adult-to-nest) 



Basis for factor 



Herons 



Blk.-cr. night 



All 



All other herons All 



Egrets 

 Great 



Snowy 



Ibises 

 Glossy 



Gulls 



Herring and 

 Gr. black- 

 backed 



Laughing 



Terns 



All 

 All 



All 



Maine, Mew 

 Hampshire 

 All other 



All 



Dbl.-cr. cormorant All 



X 2.5 



X 1.0 



X 1.0 

 X 1.0 



X 1.0 



X 0.6 

 X 1.0 

 X 1.0 



X 0.66 



X 0.66 



X 1.0 

 X 1.0 

 X 0.5 



X 1.7 



Conservative estimate 

 of regression 



Field observations 



Aerial photo 



Adult/nest ratio 

 in several colonies 



Field observations 



Regression 



Regression 



Adult/nest ratio 

 in 3 colonies 



Regression 



Assumed to be 

 similar to above 



Regression 



Aerial photo 



Aerial photo 



Regression 

 (8 colonies) 



^Factor is the reciprocal of the regression coefficient (b) when based on linear 

 regression. Factor converts adult estimate to nest number. 



49 



