A4. Habitat security 



Harlequin ducks can be displaced by instream river use (Clarkson 1992, Hunt 1993), 

 particularly on narrow streams. Instream recreational activities may be more disruptive when 

 conducted during the prenesting and early brood-rearing season (May-July) than when conducted later 

 in the breeding cycle (August and September). Human activities along the banks may also displace 

 birds and indirectly impact reproduction (Wallen 1987). 



Management considerations: boating use, angler use, hiking, camping, and land management activities 

 in and along streams during the breeding season. 



A5. Migration, molting, and wintering conditions 



Harlequin ducks breeding in the Rocky Mountains migrate to northern Pacific coastlines to 

 molt and winter. Habitat conditions in these areas are critical to maintaining breeding subpopulations 

 in Idaho, Montana, and Wyoming. Potential direct threats to harlequin duck survival include oil spills 

 and other contamination in breeding and wintering areas. Besides being an immediate mortality factor, 

 residual oil may eliminate reproduction by chronically recontaminating birds (Patten 1993). 



Management considerations: oil and other pollution, encroachment of shoreline development and 

 commercial activities on wintering or molting areas. 



Overutilization for commercial, recreational, or educational purposes. 



Bl. Overharvest 



Overharvest of remnant populations on wintering areas likely occurred and may be continuing 

 to occur in the Atlantic. This long-lived species has a relatively low reproductive rate as well as 

 delayed reproduction and probably cannot withstand significant increases in adult mortality. This is 

 compounded by use of near shore habitats that makes the species relatively vulnerable to hunting from 

 shore. Currently there is little evidence of significant hunting pressure on the Pacific population 

 outside localized areas in Alaska. However, sea duck hunting is gaining popularity on the west coast 

 and the species occurs in such low numbers in the Rocky Mountains that it could be easily affected by 

 minimal coastal hunting pressure. 



Management considerations: migratory waterfowl harvest regulations. 



C. Predation and disease. 



There is currently no evidence of excessive levels of predation and disease on harlequin 

 ducks. 



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