Harlequin duck (Histrionicus histrionicus): United States Forest Service/Bureau of Land Management habitat conservation assessment and conservation strategy for the U. S. Rocky Mountains

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This Habitat Conservation Assessment and Conservation Strategy addresses the status and conservation of harlequin ducks (Histrionicus histrionicus) 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 this region and identifies potential threats to the species’ viability there. The conservation strategy identifies management actions and information needed to maintain viable populations and protect and maintain critical habitats on lands administered by the U. S. Forest Service (USFS) and Bureau of Land Management (BLM). Implementation of the conservation strategy should 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 this region. 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 degree 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 breeding occurrences in this region occur on federal lands, primarily managed by the USFS and National Park Service. However, approximately 25% of these occurrences 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; presence of overhanging bank vegetation, woody debris, and 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, and water quality and activities that increase disturbance during the breeding season. Habitat conditions in migratory and coastal areas are also critical to conservation of harlequin ducks. Harlequin ducks that breed 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 include establishing stream buffers, maintaining instream flows and water quality, and reducing or not increasing human disturbance. Protocols are included for monitoring the U.S. Rocky Mountain harlequin duck population size and trend and for individual project inventory and monitoring. Areas where additional information is needed regarding basic ecology and management are identified, and suggestions for increasing management personnel and public knowledge of harlequin ducks and their conservation are included.

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ELECTRONIC FILE - Zoology

SWAP (2/19/2016) citation:
Cassirer EF, Reichel JD, Wallen RL, Atkinson EC. 1996. Harlequin duck (Histrionicus histrionicus) United States Forest Service/Bureau of Land Management habitat conservation assessment and conservation strategy for the U.S. Rocky Mountains. Lewiston (ID): Idaho Department of Fish and Game. 50 p.

Citation with additional information: Cassirer EF, Reichel JD, Wallen RL, Atkinson EC. 1996 Dec. Harlequin duck (Histrionicus histrionicus): United States Forest Service/Bureau of Land Management habitat conservation assessment and conservation strategy for the U. S. Rocky Mountains. 50 p. Unpublished technical report. Sponsored by U.S. Forest Service, National Park Service, National Geographic Society, Idaho Department of Fish and Game, and Wyoming Game and Fish Department.