Following mink (Musteia vison) introduction to Iceland, Harlequin populations substantially 

 declined in several areas, and changed nesting sites in others (Bengtson 1966). Predators took 9 

 nests in Iceland (n=89) and included Raven (5), mink (2), Arctic Skua (1), and arctic fox (1) 

 (Bengtson 1972). Additionally 2 nests were deserted and I failed to hatch (Bengtson 1972). 

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



RANGE 



Dispersal from natal stream All juveniles leave the natal stream soon after fledging (Reichel 

 and Center 1996, Cassirer and Groves 1994). Of 100 ducklings banded in Montana in 1992-93, 

 seven males marked as juveniles were seen only on the coast, none have been reported from their 

 natal stream (Ashley 1995, Reichel and Genter 1996). 



In Alaska, one brood was reported to use a Stellar Lake when very young, moving down to 

 Stellar Creek when older, and finally used Stellar bay and the lower tidal portion of Stellar Creek 

 when Class IIc-3 (Dzinbal 1982). 



Fidelity to natal stream. Of 100 duckling 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 both on the coast and the natal breeding stream. 

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

 their natal stream (Ashley 1995, Reichel and Genter 1996). 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 were re-observed (n=27). 



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 Firmegan 19930 up 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 pair/km in 1974 and 0.91 pair/km in 1975 (Kuchel 1977). 

 On the Rocky Mountain Front, densities ranged fi-om 0.05 pairs/km to 0.21 pairs/km (Diamond 

 and Firmegan 1993). 



In Idaho, pair densities averaged 0. 19 pairs/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 aduhs per km surveyed ranged fi-om 0.07 to 

 1.21; densities per km surveyed including juveniles ranged from 0.07 to 2.37 (Thompson et al. 

 1993, 1994). 



On the Bow River in Banff National Park, densities observed were the highest known fi-om 

 streams in North America, ranging from 2.4 ducks/km on a 15 km reach to 6.2 on a 16 km reach 

 (Smith 1996). 



On Kodiak Island, Alaska, density of breeding Harlequin pairs ranged from 0.63 pairs/km 

 along the Ayakulik River to 1.98-7.24 birds/km in 3 coastal bays (Zwiefelhofer 1994). Dzinbal 

 (1982) reported 1.3-1.8 pairs/km on two small coastal streams in Alaska. 



On the Laxa River in Iceland, Harlequins are apparently at densities higher than other known 

 stream populations (Bengtson 1972). Twenty populations in Iceland ranged fi-om 0.2 to 8.5 



15 



