Craighead (1979). Using this density estimate a total of 20 bald 

 eagles were estimated to winter along the 52.5 miles of river 

 inundated by the Libby Dam project. Two historical reports of bald 

 eagle winter use along the Kootenai River were located. Zajanc 

 (1948) reported the large number of eagles (species designation not 

 made) observed along the river may have been preying on the bighorn 

 sheep and limiting the size of the Ural-Tweed herd. U.S. Dep. 

 Agric. (1968) reported bald eagles were observed along the river 

 from Libby north to the United States-Canada border. These reports 

 indicate the estimate of 20 wintering bald eagles along the inun- 

 dated portion of the Kootenai River was probably a minimal esti- 

 mate. During the winter of 1978-79, Craighead and Craighead (1979) 

 observed 1 to 4 bald eagles wintering along Lake Koocanusa. 



In addition to the wintering population, a limited amount of 

 nesting occurs along the Kootenai River valley. U.S. Forest Ser- 

 vice records indicated the historical presence of 2 to 3 fc>ald eagle 

 nesting territories within the project area before con-struction. 

 During the 1983 nesting season there were 3 active territories (1 

 known and 2 suspected) along Lake Koocanusa (G. Altman 1983, pers. 

 commun., D. Godtel 1983, pers. commun.). The total productivity of 

 these nests is not known. A nest which was active in 1980 is no 

 longer active (D. Godtel 1983, pers. commun.). 



4) Assessment of Impacts 



The major impact to the bald eagle population utilizing the 

 project area was the loss of wintering and nesting habitats. Form- 

 ation of Lake Koocanusa inundated 52.5 miles of river which remained 

 relatively ice free during the winter and provided suitable forag- 

 ing habitat. The lake becomes at least partially ice covered 

 during severe winters with only limited use by bald eagles (Craig- 

 head and Craighead 1979). Loss of this habitat may have been 

 partially offset by the additional food supply (injured fish) 

 provided below the dam; hov/ever, due to the habitat partioning 

 observed by Craighead and Craighead (1979), displacement of indi- 

 viduals to this area probably did not take place. 



Presence of a road along both sides of thie reservoir increased 

 the level of human disturbance and v/hen combined with the inunda- 

 tion of nesting habitat has limited the availability of suitable 

 nest sites along the reservoir. 



5) Estimated Losses Due to the Project 



- 16-19 bald eagles lost due to inundation of winter habitat. 



- Qualitative loss estirrate - moderate (wintering only) . 



6) Derivation of Loss Estimate 



A population of 20 wintering bald eagles was estimated to use 

 the in'ondated reach of the Kootenai River prior to the construction 

 of che Libby Dam Project. This estimate was calculated by using a 

 density of 1 bald eagle per 2.58 miles of river for the 52.5 miles 



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