select different prey (primarily Ephe.meroptera, Trichoptera, and 

 Oiptera, with very few Simuliidae) (F^itchell 1963). Mallards, common 

 goldeneye, spotted sandpipers, a river otter were observed i; the 

 relatively slow water between rock benches at the head of the Falls. A 

 beaver was seen along a minor channel on the south bank of ttie river at 

 a time when discharge war relatively low. Common ravens and common 

 crows were occasionally seen on exposed rocks at the head of the Falls, 

 presumably drinking or scavpnging on carrion trapped on the exposed 

 recks or logjams. Harlequin ducks were also observed in fairly quiet 

 side channels just below the Falls or perched on rocks adjacent to the 

 main channel . 



Slow Water . Relatively slow, deep water occurs both above and 

 below the Falls; its distribution and extent are controlled largely by 

 the pattern of discharge from Libby Dam. Large flocks of mallards, 

 common goldeneye, and common mergansers were frequently seen swimming in 

 this habitat; harlequin ducks, Canada geese, Barrow's goldeneye, American 

 wigeon, belted kingfishers, and ring-billed and California gulls were 

 seen less frequently. Spotted sandpioers, great blue herons, ana dippers 

 used shoreline areas for feeding. Csprey and (presumably) bald eagles 

 use these relatively slow and deep stretches of the river for feeding. 

 Otter, muskrat, and beaver were also observed in slow water. 



Fast Water . Constricted areas, especially the main river channel 

 in the gorge below the Falls, are characterized by fast, turbulent flows 

 and are used by a few species, including mallards, common goldeneye, 

 harlequin ducks, common mergansers, and dippers. 



Aquatic Vegetation (Rooted) . The mallard, common merganser, and 

 river otter were the only species seen using this very limited habitat, 

 which occurs only in a relatively quiet backwater-like area at the head 

 of the Falls on the south bank of the river. A mallard brood used this 

 area extensively, and it apparently provides the only suitable brood- 

 rearing habitat for puddle ducks in the Falls area. 



Sparsely Vegetated Habitats 



Exposed Rock or Logjams (in River) . A peninsula of boulders and 

 rocky rubble extends into the river from the south bank just upstream 

 from the head of the Falls; when cut off from shore by high discharges, 

 these rocks were preferred loafing habitat for "clubs" of harlequin 

 ducks, and were used also by spotted sandpipers, dippers, ring-billed 

 gulls, mallards, and Barrow's and common goldeneye. Small islands of 

 exposed rock and the log and debris jams at the head of the Falls were 

 extensively used as loafing habitat (or as perching areas between feeding 

 bouts) by great blue herons, mallards, harlequin ducks, common mergansers, 

 ring-billed gulls, dippers, common crows, and brown- headed cowbirds. 

 Dippers were the most characteristic species on exposed rock surrounded 

 by water below the Falls. 



74 



