The Harlequin duck (Histrionicus histrionicus) is a small sea duck inhabiting the northern regions of the Northern Hemisphere. The species breeds in fast-moving streams and rivers in northwestern and northeastern North America, Greenland, Iceland and northern Europe and Asia. It winters in marine habitats of temperate and cold seas. In North America, Harlequin ducks breed in Canada and the western United States, and winter along the Pacific and Atlantic coasts.
The Harlequin duck population in Canada likely numbers in the tens to hundreds of thousands. However, coming up with a precise estimate is challenging due to the remoteness of their breeding areas and wariness around humans. Regular nationwide surveys are not carried out for Harlequin ducks, but some regional estimates are available. In this article, we will explore what is known about Harlequin duck numbers and distribution in Canada, and the challenges involved in accurately determining their population size across this vast country.
Breeding Distribution and Habitat in Canada
The core of the Harlequin duck’s breeding range in North America lies in northwestern Canada. Their breeding habitat consists of fast-flowing streams and rivers, often within forested mountain valleys. In Canada, Harlequins breed in:
– The Yukon Territory
– The Northwest Territories
– Northern British Columbia
– Western Alberta
– Labrador
Nesting tends to occur close to rapids, cascades and waterfalls, where the white noise provides cover from predators. Females lay 5-7 eggs in nests on the ground very close to the water’s edge. The ducklings hatch in late May or June, and soon head to the water where the female leads them downstream to feeding areas.
Harlequins prefer relatively pristine breeding rivers, and are sensitive to human disturbances like logging near riverbanks. Protection of breeding areas and maintenance of natural river flows are important for conservation.
Wintering Distribution and Habitat
After breeding, Harlequins migrate in late summer and fall to coastal wintering sites. There are three main wintering areas for Canada’s Harlequins:
– The Atlantic Coast, from the Canadian Maritimes south to New England
– The Pacific Coast, from Alaska to Washington
– The Great Lakes and St. Lawrence River
Harlequins favor areas with extensive rocky shores and crashing surf. Their winter diet consists of mollusks, crustaceans, echinoderms, and small fish. At favored spots, flocks of several hundred Harlequins may gather.
Population Estimates
Due to the challenges of surveying their remote boreal forest breeding areas, estimates of the total Harlequin duck population in Canada vary widely:
– In the 1996 national survey of waterfowl, the North American Harlequin duck population was estimated at 278,000, with 190,000 in western North America and 88,000 in eastern North America. However, the authors considered these results tentative.
– In British Columbia, breeding surveys between 1995 and 2011 indicated a stable population of about 10,000 individuals.
– Surveys of Harlequins wintering in the Strait of Georgia in British Columbia found around 5,000 birds in 1999.
– Breeding surveys in the Northwest Territories from 1987-2016 gave a rough estimate of 5,000-10,000 pairs, or 10,000-20,000 breeding individuals.
– Harlequin numbers in eastern Canada may be around 30,000-60,000 breeding individuals.
– One 1994 study summarized population estimates for different regions of Canada and arrived at a tentative national total of 50,000-100,000 Harlequins.
Based on this information, a very rough estimate for Canada’s total Harlequin duck population likely falls somewhere between 50,000 and 200,000 individuals. However, the true number is uncertain without comprehensive nationwide surveys on the breeding grounds. Trends over time are also unclear. Continued monitoring efforts are important, especially in remote northern regions where industrial development poses threats.
Threats and Conservation Status
The Harlequin duck is not considered globally threatened, and is classified as Least Concern by the IUCN Red List. However, some regional populations may be declining.
Threats to Harlequins include:
– Habitat degradation – Dam construction, water diversions, logging and road-building can alter river flows and riparian habitat quality.
– Disturbance – Harlequins are very wary and may abandon nesting areas with too much human recreation. Motorized boats can also flush wintering flocks.
– Oil spills – Spills in coastal wintering areas can kill significant numbers.
– Predation – Nest predation by terrestrial mammals may be increased by human infrastructure like roads near rivers.
– Hunting – Harlequins are hunted as game birds in some regions of Canada. Strict limits help regulate harvest impacts.
Several measures can help protect Harlequin duck populations:
– Habitat protection in key breeding and wintering areas.
– Limits on development like hydroelectric dams in intact watersheds.
– Enforcement of shoreline buffers along breeding streams.
– Restrictions on motorized boats in sensitive estuaries.
– Careful regulation of subsistence hunting where it occurs.
Research Difficulties
Getting accurate, current estimates of Harlequin duck numbers across Canada is challenging for several reasons:
– Remoteness of breeding habitat – Inland breeding streams are scattered across thousands of square kilometers of rugged wilderness in the Yukon, Northwest Territories, and northern British Columbia and Quebec. Access is very difficult and expensive.
– Lack of breeding season surveys – Unlike more southerly waterfowl, Harlequins are not covered by the North American Breeding Bird Survey due to their boreal distribution. Flightless molting periods also preclude some survey methods.
– Wariness – Harlequins are easily flushed and disturbed by approaching boats or planes used in surveys. This makes them harder to detect.
– Weather – Cold, wet conditions during the breeding season limit survey windows and can hamper efforts.
– Vast wintering range – Harlequins disperse widely across three coasts after breeding, making comprehensive winter surveys logistically impractical.
– Lack of marking/tracking studies – Banding and radiotelemetry studies that follow individuals through the year could shed light on population connections and migration, but have not been widely implemented.
Overall, rough estimates from regional surveys likely provide a ballpark idea of Harlequin numbers in Canada. However, uncertainties will remain until major nationwide monitoring efforts can be implemented on the remote breeding grounds.
Recent and Ongoing Monitoring Efforts
Some recent and current initiatives aim to improve monitoring and knowledge of Harlequin ducks in parts of their Canadian range:
– Increasing surveys on Pacific wintering areas in British Columbia, to improve seasonal population trend estimates.
– Government surveys of breeding rivers in the Northwest Territories between 1987-2016. This dataset provided the first abundance estimate for the territory.
– Monitoring by Parks Canada of Harlequin breeding populations and habitat in national parks like Banff and Jasper.
– Assessing mercury contamination levels in Harlequins at wintering and breeding sites, in collaboration with hunters who provide samples.
– Tracking the effects of hydroelectric development on Harlequins along the Churchill River in Labrador.
– Using satellite imagery to identify and monitor remote Harlequin breeding sites in northern Quebec and Labrador.
– Motivating and training local indigenous groups to participate in surveys across remote northern regions.
– Analyzing movements using leg band and radio telemetry studies of Harlequins breeding in the Yukon Territory.
Filling in major gaps in distribution, abundance and population trends will require expanding monitoring into wider areas of northern Canada via partnerships, local involvement, and deployment of new technologies like drones and satellites. Consistent, long-term datasets will also be key to detecting any future population changes.
Conclusions
– The Harlequin duck breeds across northern Canada, and winters along the Pacific, Atlantic and Great Lakes coasts.
– The total Canadian population is uncertain, but likely numbers at minimum in the tens of thousands, up to 200,000 individuals or more.
– Major gaps remain in coverage of breeding surveys, especially in remote regions like the northern Canadian Cordillera and Quebec/Labrador.
– Improved monitoring is required to provide accurate abundance and trend estimates needed for effective conservation.
– Ongoing threats like habitat alteration and disturbance make continued focus on Harlequin duck populations a priority.
– Better data will come via expanded surveys, local community involvement, technological solutions, and long-term, consistent monitoring programs.