National Park) were large. Annual differences in success rates from 1989-1992 were primarily 

 associated with the amount and timing of runoff. High runoff, particularly in June-early July, 

 and runoff in years with "double peaks" caused lower reproductive success. This was 

 particularly evident in 1991 (Reichel and Center 1994) the only year where runoff exceeded 

 20,000 cfs and when production was lowest (24%). The changes in reproductive success were 

 primarily due to changes in numbers of broods per pair, not changes in the size of successful 

 broods. This indicated that differences in mortality were due to events that affected entire 

 clutches or very young broods during that time period. This pattern was not evident in the 1994 

 season. The runoff was not particularly high, nor did it have a pronounced double peak. There 

 were no obvious differences between runoff patterns on the South Fork Flathead drainages vs 

 Middle Fork, North Fork, or Lower Clark Fork where success rates were very low. While rates 

 are not statistically comparable because pair counts were not on 2 of 4 South Fork drainage 

 streams surveyed for broods, differences appeared large in both number of broods and brood 

 sizes. It seems apparent that our understanding of factors contributing to the success or failui2 of 

 harlequin reproduction is still far from complete. 



Capture and Marking 



We continued to make progress during the third year of the juvenile Harlequin Duck site 

 fidelity and survival study. A total of 19 juvenile birds from 5 drainages were captured and 

 marked (Table 3, Appendix D). Seven adult males and 7 adult females were also marked in 1994 

 (Table 3, Appendix D). This is a lower number than 1992 or 1993 due to a combination of: 1) 

 low reproduction on many streams, 2) many adults present were marked in previous years, and 3) 

 difficulty capturing some broods. 



