M. BALD EPGLES 



1) Introduction 



Use of the Kootenai River by the northern bald eagle, an 

 endangered species within the United States, has been concentrated 

 from late fall to early spring. The spavming run of mountain 

 whitefish (Prosopium williamsoni) combined with the abundant car- 

 rion associated with the wintering populations of big game provided 

 a stable food supply during this period. Limited nesting has been 

 documented along the Kootenai River from the confluence of the 

 Fisher River north to the United States-Canada border. 



2) Seasoial Habitat Preference 



From mid-October to late March, a number of winter resident 

 and migratory bald eagles have been observed using the open water 

 areas along the Kootenai and Fisher rivers (Craighead and Craighead 

 1979, unpublished U.S. Forest Service files, Rexford Ranger Dis- 

 trict). Based on the historic information it was assumed portions 

 of the river remained ice-free during the winter and provided 

 suitable habitat for winter bald eagles. Preferred streamside 

 perch trees are large (remnant) snags of western larch and western 

 redcedar which project above the surrounding forest; cottonwood, 

 Douglas-fir, birch and spruce are also frequently used (McClelland 

 1973, Craighead and Craighead 1979, U.S. Dep. Inter. 1983). Barren 

 areas associated with gravel bars, river bars and shoreline also 

 provided foraging and nesting sites. Craighead and Craighead 

 (1979) observed bald eagles partitioned the available habitat along 

 the open water area, limiting the total number of eagles that could 

 occupy a given reach of the river. 



During the nesting season, active territories have been ob- 

 served along the Kootenai River valley. Nesting bald eagles typi- 

 cally select tall snags or live trees within a few hundred yards of 

 water (Evans 1982). Within the region, nests are associated both 

 with rivers and lakes (Shea 1973, B. McClelland 1983, pers, 

 commun.). The one known active nest site along the Kootenai River 

 in Montana is located in the riparian zone along the river. 



In their report, Craighead and Craighead (1979) found a vari- 

 ety of food items v/ere utilized. Start of the fall concentration 

 of bald eagles coincided with a major spawning run of mountain 

 whitefish up the Fisher River. After the spavming run, fish killed 

 or injured while r;assing through the generating turbines contained 

 within the Libby Dam £)owerhouse, and big game carrioii asso<:;iated 

 with the extensive winter ranges provided the majority of the food 

 supply. Limited use of waterfowl carcasses was also observed. 



3) Population Status 



During the winter of 1978-79, an a\/erage density of one bald 

 eagle per 2.58 niles of open water was observed by Craighead and 



