EXECUTIVE SUMMARY 



Harlequin ducks ( Histrionicus histrionicus ) are sea ducks that migrate to mountain streams to 

 breed. The species is classified as a U. S. Forest Service sensitive species in the Northern, Rocky 

 Mountain, and Pacific Northwest Regions, a state sensitive species in Oregon, a priority habitat species 

 in Washington, and a species of special concern in Idaho, Montana, and Wyoming. Harlequin ducks 

 are also classified as migratory waterfowl covered under general waterfowl or sea duck regulations 

 throughout their range. 



This Conservation Assessment and Strategy addresses the status and conservation of harlequin 

 ducks in the Rocky Mountains of Idaho, Montana, and Wyoming. The Conservation Assessment 

 summarizes available information on the ecology and population status of the harlequin duck in Idaho, 

 Montana, and Wyoming, and identifies potential threats to the species' viability in this region. The 

 Conservation Strategy identifies management actions and information needed in order to maintain 

 viable populations and protect and maintain critical habitats to ensure that listing is not warranted, in 

 accordance with the Endangered Species Act (ESA) of 1973, as amended. 



The Conservation Assessment is based on inventory, monitoring, and research data collected in 

 the U.S. Rocky Mountains since 1974. Approximately 300 pairs of harlequin ducks are estimated to 

 breed in 57 breeding or probable breeding occurrences in the U.S. Rocky Mountains. A breeding 

 occurrence is considered a single "breeding area", but may contain portions of several streams not 

 separated by more than 10 km of unsuitable habitat, or 20 km of unoccupied, suitable habitat. Data 

 gathered from marked individuals indicates a high degeree of fidelity to these breeding occurrences. 

 The harlequin duck breeding occurrences identified in the U.S. Rocky Mountains are comprised of 

 reaches on 128 streams. Over 90% of the harlequin duck breeding occurrences in the U.S. Rocky 

 Mountains occur on federal lands, primarily managed by the U.S. Forest Service and National Park 

 Service. However, approximately 25% of these do cross some privately-owned land. The remaining 

 7% (4 breeding occurrences) are located predominantly on state and privately-owned land. 



Not all Rocky Mountain breeding occurrences have been located. Potential breeding habitat is 

 identified as 2nd-order or larger streams containing reaches with average gradient of 1 % - 7 % , riffle 

 habitat, clear water, gravel to boulder-sized substrate, and forested bank vegetation. Additional 

 characteristics that may increase likelihood of use by harlequin ducks include: proximity to occupied 

 habitat, overhanging bank vegetation, woody debris, loafing sites, absence of human activity, and 

 inaccessibility. 



Potential threats to harlequin ducks in the U.S. Rocky Mountains include activities that affect 

 riparian habitats, water yield, water quality, and increase disturbance during the breeding season. 

 Habitat conditions in migratory and coastal areas are also critical to conservation of harlequin ducks. 

 Harlequin ducks breeding in the Rocky Mountains have been located off the coasts of Oregon, 

 Washington, and British Columbia. Harvest in coastal areas, while apparently low, could also 

 potentially affect harlequin ducks in the Rocky Mountains. 



The Conservation Strategy emphasizes an adaptive approach for maintaining riparian and 

 instream harlequin duck habitat. Guidelines are designed to maintain habitat quality by avoiding 

 degradation from timber harvest, road construction and maintenance, mining, livestock grazing, water 

 developments, and recreation. Guidelines include establishing stream buffers, maintaining instream 

 flows and water quality, and reducing or not increasing human disturbance. Inventory and monitoring 

 protocols are included for assessing the U.S. Rocky Mountain harlequin duck population size and trend 

 and for individual project inventory and monitoring. Finally, areas where additional information is 

 needed regarding basic ecology and management and methods to increase knowledge of management 

 personnel and the public about harlequin ducks and their conservation are identified. 



