where bank vegetation was open. The Boulder River also had a mean 

 gradient <3 degrees, which Wallen (1987) considered a requirement 

 of harlequin breeding habitat. However, all the streams surveyed 

 during this study had a mean gradient in this range. Finally, the 

 harlequin duck observation area (Figure 3) appeared to have 

 suitable nesting habitat in terms of backwater areas and beaver 

 ponds with dense perennial shrubs around the edges. However, 

 these areas usually were within a few meters of a heavily used 

 road. Public use along the river appeared to be moderate except 

 in close proximity to the road and campgrounds. Wallen (1987) 

 found that harlequin ducks, especially hens with broods, tended 

 to avoid areas with much human activity. 



The only streams surveyed that did not appear to offer 

 suitable harlequin duck habitat were Mill, Taylor, Cabin, and 

 Hyalite creeks. Mill Creek paralleled the road for most of its 

 length, which forced the creek into a narrow rocky channel with 

 steep banks. The only area that appeared suitable in terms of 

 channel and gradient had open banks with little vegetation. 

 Taylor Creek was at the lower limit of size and the upper limit 

 of gradient and had little or no vegetation along the banks. This 

 was the only stream surveyed where dippers were not observed. 

 Both Cabin and Hyalite creeks probably were too small and steep 

 for harlequin ducks, having channels confined to narrow canyons. 



The West Boulder and Stillwater rivers were very similar in 

 physiogamy with the exception of the Stillwater River's much 

 greater size. Both had sections of calm open water flowing 



18 



