Exposure and predation . Predation on eggs by river otters (Lutra canadensis) and by 

 black bears (Ursus americanus) has been reported in Washington (Jeff Foster unpubl. data, in 

 Schirato 1993). 



Following mink (Mustela vison) introduction in Iceland, Harlequin populations 

 substantially declined in several areas and changed nesting sites in others (Bengtson 1 966). 

 Predators including the Raven {Covus corax) (5), mink (2), Parasitic Jaeger (Stercorarius 

 parasiticus) (1), and arctic fox (Alopex lagopus) (1) took 9 nests in Iceland (n==89) (Bengtson 

 1972). Additionally, 2 nests were deserted, and 1 failed to hatch (Bengtson 1972). Arctic Skuas 

 were seen taking 2 chicks in Iceland (Bengtson 1972). 



RANGE 



Dispersal from natal stream. In Montana, juveniles apparently leave the natal stream 

 soon after fledging. At least 13 broods fledged prior to leaving the breeding stream (n=69) and 

 many more may have waited that long, but follow-up surveys were not done. In McDonald 

 Creek, Montana, Kuchel (1977) reported that at least one brood had left prior to fledging, 

 apparently swimming across McDonald Lake and drifting downstream. In Alaska, one brood 

 was reported to use Stellar Lake when very young, moving down to Stellar Creek when older, 

 and finally using Stellar Bay and the lower tidal portion of Stellar Creek when Class IIc-III 

 (Dzinbal 1982). 



Fidelity to natal stream. Of 100 ducklings marked in 1992-93 in Montana, 14 females 

 are known to have survived at least 2 years. Of the 14 surviving females, 5 were reported only 

 from their natal stream, 1 only from the coast, and 8 from both the coast and the natal breeding 

 stream. Seven males marked as juveniles were seen only on the coast; none have been reported 

 fi-om their natal stream (Ashley 1995, this report). In Glacier National Park, 2 of 5 ducks banded 

 as juveniles in 1974 returned to the natal stream in 1976; both were females (Kuchel 1977). 



No ducklings marked from 1988-1991 in Idaho have been re-observed (n=27) (Cassirer 

 pers. comm.). 



Adult fidelity to breeding stream. In Montana, all 3 males marked as adults and later 

 seen on the wintering grounds returned to the breeding grounds the following year. A single 

 female (n==47), marked on McDonald Creek Montana in 1 992 and not seen there since, was 

 observed on Hornby Island, British Columbia, in March of 1995 and 1996. Given the intensive 

 survey effort in Montana during that period (Figure 1, Appendix G), it is likely that she had 

 substantially shifted her breeding location since being originally marked. This case constitutes 

 the only evidence that breeding streams may be abandoned. 



POPULATION STATUS 



Estimates or counts of density. Densities of Harlequins on breeding streams range from 

 0.05 pairs/km on a stream in Montana (Diamond and Finnegan 1993) to 8.5 pairs/km on part of 

 the Laxa River in Iceland (Bengtson and Ulfstrand 1971). In Montana, pair density on a 16 km 

 section of McDonald Creek was 0.67/km in 1974 and 0.91 /km in 1975 (Kuchel 1977). On the 

 Rocky Mountain Front, densities ranged from 0.05 pairs/km to 0.21 pairs/km (Diamond and 

 Finnegan 1993). 



In Idaho, pair densities averaged 0.19/km (range 0.08-0.57) of occupied streams surveyed 

 (Cassirer 1995). From 1990 through 1992, densities there averaged 0.06-0.53 pairs/km (x = 

 0.22) (Cassirer 1993). In Oregon, densities of adults per km surveyed ranged from 0.07 to 1.21; 



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