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Harlequin Duck Life History


Rivers and Streams

Harlequin Ducks breed in subalpine or coastal habitats. They are most common in fast-flowing sections of rivers early in the breeding season, but move to slower-moving stretches of rivers and lakes once the chicks have hatched. They tend to use streams and rivers with small islands and sandbars for resting. In the winter, they are found almost exclusively on rocky coastal shorelines. In the East, they require exposed headlands and often rest on boulders and rocks. In the West they can be found near cobble beaches, usually over eelgrass and kelp. At night they roost on open water farther from shore.

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Aquatic invertebrates

Harlequin Ducks eat mostly aquatic invertebrates and small fish. On breeding grounds, they eat aquatic insects such as midges, and fish eggs. On wintering grounds, they take tidal marine invertebrates, including crustaceans such as crabs, amphipods, and barnacles; mussels, limpets, periwinkles, snails; and insects.

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Nest Placement


Harlequin Ducks nest on cliff ledges, in holes in trees, and sometimes on the ground. The female selects the nest site.

Nest Description

Harlequin Ducks make nests of conifer needles, mosses, leaf litter or small stones, and line them with down feathers.

Nesting Facts

Clutch Size:4-8 eggs
Number of Broods:1 brood
Egg Length:2.0-2.4 in (5.1-6.2 cm)
Egg Width:1.4-1.6 in (3.6-4.1 cm)
Incubation Period:27-29 days
Egg Description:Pale creamy to pale buff.
Condition at Hatching:Covered in down and able to leave the nest soon after hatching.
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Surface Dive

The Harlequin Duck is a small, active waterfowl species. It is an excellent swimmer and able to maintain its position even in very rough conditions. Harlequin Ducks feed by diving underwater, propelled themselves by their feet with wings held slightly outstretched for steering. Dives can be as deep as 70 feet and last as long as 45 seconds. Small items are consumed underwater while larger items are brought to the surface. Harlequin Duck pairs are monogamous and long-term. They maintain pair bonds through the winter and from year to year. Males and females participate in pair-bonding displays throughout the winter that include head-nodding and “rushing,” in which pairs hold their heads low and scoot quickly across the water at an intruder. Upon return to their breeding territories females select a nest site, often taking more than an hour to inspect every nook, cave, and bush on the territory. They occasionally reuse old nest sites. Only the female incubates the eggs while the male departs for molting grounds on the coast soon after incubation begins. Upon hatching the female leads her brood to slower-flowing waterways with plentiful insects. Young are able to forage immediately after hatching, but do not dive regularly until they are 3–4 weeks old. Harlequin Ducks are very social, especially in the nonbreeding season when they form large groups at food-rich areas. Even at the end of the breeding season males form post-breeding “clubs” with failed and nonbreeding females.

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Low Concern

Partners in Flight estimates a global breeding population of 170,000 and rates the species a 12 out of 20 on the Continental Concern Score, indicating low conservation concern. Much of the species’ range lies in remote northern North America, beyond the reach of the North American Breeding Bird Survey, so there is little information on Harlequin Duck population trends. Wintering populations in eastern North America are much smaller than historical (late 1800s) numbers. It’s not clear what the primary cause of declines might be. Logging of their forest breeding habitat can be a concern, as disturbed areas disrupt stream flow and cause an influx of silt, which can affect their invertebrate prey. As a coastal species, Harlequin Ducks are susceptible to oil spills as well as polluted runoff. Bioaccumulation of heavy metals from oil production is an increasing concern for sea ducks in general.

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Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Robertson, Gregory J. and R. Ian Goudie. (1999). Harlequin Duck (Histrionicus histrionicus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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