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[Ecoprov.]

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Characteristics and Range The Harlequin Duck is renowned for the striking plumage of the male and for its tolerance of turbulent water: it favours fast-flowing mountain streams for breeding and rocky-cobble seashores during the rest of the year. In North America there are two disjunct populations, the eastern (Atlantic) and western (Pacific); the latter population is much larger (Robertson and Goudie 1999, Sea Duck Joint Venture 2004). The species also breeds in Greenland, Iceland, eastern Russia and Japan. In western North America the Harlequin Duck breeds primarily in mountainous country from Alaska to the southern Rocky Mountains, and winters along the Pacific Coast from the Aleutian Islands to California. British Columbia likely supports 12,000-15,000 wintering birds (Rodway et al. 2003), which breed within the province and in bordering provinces and states (Campbell et al. 1990, Robertson and Goudie 1999).

Distribution, Abundance, and Habitat The Atlas shows breeding concentrations in parts of the Coast and Mountains, Southern Interior and Southern Interior Mountains ecoprovinces, with a few scattered breeding records elsewhere. Breeding evidence was found from 250 to 1,500 m in elevation. In general these distribution patterns are similar to those reported by The Birds of British Columbia in 1990, although the data there indicate use of higher elevations. The highest Probabilities of Observation were in the mainland portion of the Coast and Mountains Ecoprovince north of the Strait of Georgia, likely due to greater search effort there during the Atlas project.

Detection of Harlequin Ducks on the breeding grounds is hampered by the rapid disappearance of the conspicuous males, which return to the coast to moult in late May or early June, and the secretive behaviour of females on relatively inaccessible streams. Few nests have been located in British Columbia (Campbell et al. 1990) and only one nest in the Atlas effort, on southern Vancouver Island. Confirmation of breeding is primarily reports of females with ducklings. Mapping and monitoring breeding of this species is therefore difficult, unless focused on the specific breeding habitats.

When breeding, the Harlequin Duck selects fast-flowing rivers or streams in riparian, subalpine, or coastal habitats, often choosing reaches with small islands or gravel and sand bars offering quieter backwaters for loafing and raising ducklings (Robertson and Goudie 1999). Lakes, offshore islands and mainland coasts are less often used. On the breeding grounds, aquatic insect larvae and fish eggs are the primary foods.

Conservation and Recommendations The western Canadian (Pacific) population of Harlequin Duck is not considered to be at risk. Recent research in British Columbia suggests that adult survival is high and production of young birds is sufficient to maintain a stable population (CWS Waterfowl Committee 2013, Rodway et al. 2015). Potential threats affecting Harlequin Ducks at breeding sites in British Columbia include degradation of riverine habitats by logging, mining and power projects, and disturbance from white-water rafting, fishing and other recreational activities (Robertson and Goudie 1999). The introduction of sport fish, e.g., trout (Salmoninae) into rivers used by the Harlequin Duck can lead to reductions in availability of aquatic insect prey (LeBourdais et al. 2009). Breeding locations identified by the Atlas can be monitored to check for impacts of these human activities.

Acknowledgements Thanks to Michael Rodway, Sean Boyd and Ken Wright for providing useful reviews and references.

Alan E. Burger

Recommended citation: Burger, A.E. 2015. Harlequin Duck in Davidson, P.J.A., R.J. Cannings, A.R. Couturier, D. Lepage, and C.M. Di Corrado (eds.). The Atlas of the Breeding Birds of British Columbia, 2008-2012. Bird Studies Canada. Delta, B.C. http://www.birdatlas.bc.ca/accounts/speciesaccount.jsp?sp=HADU&lang=en [04 Dec 2024]