In Glacier National Park, all mortality of ducklings (through fledging took place in the first 

 three weeks of life (Kuchel 1977). This is similar to the findings of Bengtson (1966, 1972) who 

 reported that of 7 broods totaling 37 ducklings, 24 survived 1 week, 19 two weeks, and little 

 mortality was seen after two weeks. Bengtson (1972) reported that survival of ducklings ranged 

 from 40-76% on 3 streams over 5 years. 



In Montana, 249 Harlequins (39 adult males, 53 adult females, 157 juveniles) have been 

 banded fi-om 1991 through 1995 (Reichel and Center 1996). Of 58 juveniles marked in 1992, at 

 least 12 females and 2 males were ahve in 1994, and 8 females and 2 males in 1995; of 42 

 juveniles marked in 1993, at least 1 female was alive in 1995. Both males known to be alive were 

 seen on the wintering grounds. Adult males returned to the breeding streams when they were 

 alive the previous year 53% of the time while females returned at a rate of 57%. The higher 

 female rate may be due to the fact that a male may mate with a new female, which could lead him 

 to a new stream, and thus he would not be seen on the previous year's stream. 



In Idaho, 63% of aduhs (n=30) returned at least 1 year; male and female rates were not 

 significantly different (Cassirer and Groves 1994); one duck marked as an adult in 1988 returned 

 through 1993 (mimmum 7 years old). No ducklings marked fi'om 1988-1991 were re-observed 

 (n=27). In Wyoming 40% of marked aduhs returned to breeding streams (Wallen 1993). At least 

 5 females of 103 ducklings banded in 1987-1990 have returned and nested successfiilly (Wallen 

 1991). The oldest known Wyoming bird was marked as a duckling in 1985 and recaptured in 

 1991 (Wallen 1993). In Alaska, 30% (8) aduh females and 30% (3) of aduh males marked were 

 relocated the following year (Dzinbal 1982:62). 



In Iceland, 64% (20) aduh females and 48% (13) of aduh males, marked with nasal discs, 

 were relocated the following year (Bengtson 1972). Hatching success in Iceland averaged 87% 

 and ranged fi'om 84% to 91% in four years (Bengtson 1972). 



CAUSES OF MORTALITY 



Causes of death. In Montana, high water during early summer runoff was associated with 

 low productivity (Kuchel 1977, Diamond and Finnegan 1992, 1993, Reichel and Genter 1993, 

 1995). Wallen (1987) reported that following a severe July rainstorm which raised a creek level 

 0.6 m within 2 hours, both broods seen prior to the storm were never seen again; however, he 

 generally felt that drought in Grand Teton was more limiting to reproductive success than 

 flooding. Dzinbal (1982) reported higher spring run off was associated with lower reproduction 

 in a two-year study in Alaska. In Idaho, productivity was negatively correlated to June stream 

 flow (r = -0.93, p = 0.006) (Cassirer and Groves 1995). It is currently not understood what 

 causes this correlation. Possibilities include females not nesting due to high water and/or poor 

 feeding; destruction of nests within the floodplain; or loss of juveniles due to drowning, being 

 separated from the female, inability to feed effectively, or hypothermia. 



Bengtson (1972) found very low duckling survival coincided with adverse weather and very 

 low abundance of blackflies, their preferred food in his study area. 



In coastal waters. Harlequins are occasionally caught by large mussels and clams by the bill 

 and drowned (Turner 1886 //; Philips 1925) 



Exposure andpredation Predation on eggs by river otters and black bears has been reported 

 from Washington (Jeff Foster, unpubl. data, in Schirato 1993). 



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