Table 46 shows the location and the number of great blue hercn 

 and common egret nests in colonies within the project area. Colonies 

 were most numerous and nests were most abundant in 1962. Thereafter, 

 there was a general decline through the 1960 's and 1970's; cursory ob- 

 servation indicates that the number of nesting common egrets and great 

 blue herons greatly decreased during the first half of the 1970 's. 



Graber (197 6: 2) also documented a similar decline in the number 

 of breeding herons and egrets on the Mississippi River between St. Louis 

 and Cairo. He attributed the decline there to two factors: (1) dis- 

 turbance of nesting colonies by logging and "development", and (2) de- 

 terioration in their food-gathering ability stemming from increases in 

 turbidity and sedimentation. 



In our judgment the nine-foot waterway initially produced an in- 

 crease in breeding egrets and herons by enhancing their feeding grounds. 

 Their food supply and feeding areas were increased by the expansion in 

 water surface area, particularly in the lower one-third of each naviga- 

 tion pool. 



The clearing of bottomland forests in the impoundment area resulted 

 in losses in potential nest sites, but it would seem that sufficient 

 bottomland hardwoods remain to provide adequate nest sites. The in- 

 creased turbidity and sedimentation of backwater areas in recent 

 years appears to be an important factor in the recent catastrophic 

 decline in the abundance of herons and egrets. 



Cormorants 



The double-crested cormorant was a common migratory visitor and 

 bred to a limited extent in the Mississippi valley. The cormorant was 

 listed as occurring in occasional flocks in August 1888 near Quincy, 

 Illinois (Garman, 1896: 131). Smith (1911: 17) recorded several cormorants 

 nesting on Clear Lake near Havana, Illinois. Praeger (1925: 570) re- 

 ported that in 1890 the double-crested cormorant was abundant in April 

 and October near Keokuk, Iowa on the Mississippi River. Mills, Star- 

 rett, and Bellrose (1966: 21) stated that as many as 15,000 cormorants 

 were in the lower Illinois valley on October 16, 1950. 



