Bald Eagle 



Pools 24, 25, and 26 form one of the more important wintering 

 grounds for the bald eagle in the United States. Eagles funnel into 

 the upper Mississippi River from extensive breeding grounds embracing 

 Michigan, Wisconsin, Minnesota, Ontario, Manitoba, and the Northwest 

 Territories. 



As ice covers the navigation pools in the upper reaches of the 

 Mississippi River, increasing numbers of eagles move downstream to the 

 lower pools. Because of the variability in seasonal ice cover in the 

 navigation pools of the upper river, the numbers found in the project 

 area fluctuate greatly during the fall and winter (Tables 42, 43, 44, & 45). 



Pools 24, 25, and 26 are the southern terminus for the large con- 

 centration of bald eagles wintering on the Mississippi River. When 

 these pools freeze completely over, the eagles are forced to disperse 

 to less satisfactory feeding grounds. 



The nine-foot channel project has had both a beneficial and a detri- 

 mental effect upon wintering eagles. With the navigation dams, the 

 tailwaters remain unfrozen for longer periods of time than previously. 

 It is there that the eagles concentrate to catch fish during severe 

 weather in midwinter. However, the lower parts of the pools freeze 

 over earlier than prior to the project, because of the reduction in 

 channel velocity, thereby restricting the eagles' feeding area early in 

 the winter. 



Overall, the advantages the eagles gain in obtaining fish from -the 

 open tailwaters in midwinter probably outweigh the early winter loss of 

 more extensive feeding grounds caused by the navigation project. 



Herons and Their Allies 



The family Ardeidae is represented in Pools 24, 25, and 26 by the 

 great blue heron, common egret, black-crowned night heron, green heron, 

 cattle egret, American bittern, and least bittern. These are wading 

 birds that feed on fish, frogs, crayfish, and other invertebrates. All, 

 except the green heron and bitterns, breed in colonies which sometimes 

 number 100 and more nests. 



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