By far the largest nesting population of a single species existed on 

 Great Duck Island. Eugene Lesser (unpublished) estimated that 14,000 pairs 

 of Leach's storm-petrels and 400 pairs of black guillemots nested on that 

 island in 1977. Observations of only a single pair of breeding birds were 

 considered important because those birds might represent remnants of formerly 

 large colonies or pioneers forming a new colony which may become important 

 in the future. All colony sites used in 1977 are listed for each species in 

 decreasing order of size (Table 3). 



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