The male harlequin duck (Histrionicus histrionicus) is a colorful, compact sea duck inhabiting Alaska’s coasts for most of the year. The common name harlequin as well as the latin name Histrionicus (from “histrio” or stage player) come from the male plumage, said to resemble the gaily colored dress of medieval court jesters. Male harlequins are mostly a dark blue-gray, with bold accents. The face is white between the eye and dark gray bill. Black-bordered white markings include a spot over the ear, a streak on the side of the neck, a collar, and a bold sash from the shoulder to the breast. In addition, the black crown is highlighted by rust and there is a large rust patch on the flank. Females are generally a uniform grayish black, with light cheeks and spots above the eye and over the ear. Harlequin hens resemble bufflehead females that have a singular white face patch or, except for a much smaller size, female scoters. As with most sea ducks, harlequins do not mature or attain full adult plumage until they are 2 years old.
Range and distribution: There are two populations of harlequin ducks worldwide. An eastern population breeds from southwest Greenland and Iceland to Baffin Island in arctic Canada, and south into the Maritime Provinces. This population, wintering as far south as the New England states, has diminished substantially in recent years. The western harlequin duck breeds from northeast Siberia across to arctic Canada, throughout most of Alaska and British Columbia, and sparsely in the Rocky Mountain region of the U.S. as far south as California.
In Alaska, there are scattered breeding records for harlequin ducks from the eastern North Slope, northwest Alaska, St. Lawrence Island, Yukon-Kuskokwim region, Alaska Peninsula, Aleutian Islands, Gulf of Alaska coast, and Southeast Alaska. Because of their preference for nesting on mountain streams, they likely inhabit the upper portions of drainages throughout Interior Alaska, but observations are scarce in remote areas. Large numbers of harlequin ducks winter in the Aleutian Islands and Gulf Coast (particularly Prince William Sound), and throughout the southeastern coast south to Oregon.
Life history: The harlequin is one of the least studied ducks in North America, breeding and wintering in some of the wildest and most remote habitat in the northern hemisphere. Its choice of rugged habitats and relatively short migrations rarely bring it to major waterfowl gathering sites where ducks are most often observed and hunted. In fact, most of our knowledge of breeding biology and behavior came from studies conducted in Iceland. Recent work in the Rocky Mountains region and in Prince William Sound, as a result of the 1989 Exxon Valdez oil spill, is expanding our knowledge of this unique species.
Paired harlequins usually leave their coastal wintering grounds in May, but timing varies considerably according to diverse snow conditions across their broad breeding range. The migration can be a short “lateral” one, from sea coast to adjacent streams, for birds such as those breeding in Prince William Sound, or the trip may be lengthy and protracted for birds wintering in the Aleutians, destined for Siberia or late thawing Interior mountain streams. Harlequins are one of a few unrelated duck species throughout the world that have become “river specialists.” During the breeding season, the South American torrent duck, New Zealand blue duck, African black duck, and harlequin seek rapidly flowing streams and rivers for nesting and rearing young. However, the widespread harlequin is known also to breed along glacial lakes, in tundra ponds, and perhaps rarely on offshore rocks in marine waters.
Prior to nesting, pairs will make flights up streams to prospect for nest sites and suitable feeding areas. Most nests are built very close to water, on the ground in dense vegetation, among tree roots, or in rock crevices, although a nest has been found in a tree cavity. The hen lines the nest with white down, which is characteristic of cavity-nesting relatives like the goldeneyes, but unusual for ground-nesting waterfowl that usually use duller, more camouflaged feathers. Nesting females take full advantage of their unobtrusive coloration and habitat to avoid detection, and their presence is not often discovered. Only a few nests have been found in Alaska and in a wide variety of habitats and sites.
An average of six pale, buff-colored eggs are laid, at which time the male departs, sometimes returning directly to the wintering grounds to molt. Studies in Iceland have indicated that food availability on the mountain streams may limit the density of nesting birds, so departure of males may actually improve survival of females and their young. In coastal breeding areas, pairs and incubating females can make daily flights to salt water to feed. Incubation takes 30 to 32 days, longer than for any other sea duck. Young are reared in a secluded upper portion of the stream and apparently brought to the coast only when fledged. Flightless young have been observed playing in rapids and even waterfalls, which are believed to be used as escape habitat. Predation may contribute less to juvenile mortality than whitewater joy-riding!
Presence of harlequins in summer should not be interpreted as proof of local nesting, because a substantial portion of the population does not breed each year. Flocks of post-breeding males and immature harlequins, less than 2 years old, begin to form in late June and remain together to molt through August. During the molt, males lose most of their striking colors, and males and females are difficult to distinguish.
By late September, females and broods have joined the other harlequins on the coastal staging and wintering areas. As would be expected of hardy sea ducks, they endure the harsh conditions of winter ocean living. More than other species, harlequins seem to choose more rugged and exposed rocky coasts. The Aleutian Islands probably host the largest number of wintering harlequin ducks, but many are scattered throughout southcoastal and Southeast Alaska.
Food habits: On nesting streams, harlequins feed either by skimming organisms from the surface or by diving. Harlequins are better able than other ducks to contend with strong currents, spending a greater proportion of their foraging time under water among current-swept rocks and boulders. Larvae of aquatic insects are the main prey species in summer; especially those associated with the highly oxygenated waters of rushing mountain streams, such as midges, blackflies, caddisflies, and stoneflies. In late summer, the eggs of spawning salmon in the lower reaches of streams are a rich protein source for growing young and post-nesting females. Herring spawn in shallow tidal areas also provides a temporary feast for harlequins.
Harlequins are more often seen perched on rocks than any other sea duck. Unlike goldeneyes, buffleheads, and mergansers, which frequent calmer shorelines and customarily nap on the water, harlequin ducks in the choppy waters off rocky points and reefs expend considerable energy when they are on rough waters and cannot afford to sleep afloat. Perching on rocks saves energy reserves for staying warm and for vigorous bouts of feeding.
For most of the year, the harlequin duck's diet consists of a wide variety of intertidal invertebrates gathered from rocks and the bottom close to shore. Mollusks are a particularly important food group, especially snails, periwinkles, blue mussels, and small clams. Crustaceans, such as hermit crabs, shrimps, and amphipods also are major prey items. Unlike most marine birds, harlequins have the extraordinary ability to feed on limpets and chitons, animals that strongly attach themselves to rocks with suction cups. With strong nails at the tips of their bills, harlequins have learned to detach these tough morsels that resist the most ingenious beachcombers!
Because of their broad range and remote habitat preferences, harlequin ducks are seldom affected by human disturbances, such as industrial activity, urban bustle, or recreation. Much of their habitat remains pristine and they are numerous in Alaska during winter. However, they can be affected by degradation of water quality and encroachment of human development in breeding streams. We have also learned that harlequin ducks are particularly vulnerable to oil spills because they gather in coastal waters and depend on intertidal habitats close to shore. Harlequin ducks are not very productive, and they lead precarious lives in our mountain valleys and secluded coasts. A great deal needs to be learned about this hardy, flamboyant little sea duck to understand its needs and ensure its conservation.
Text: Dan Rosenberg, Sam Patten and Tom Rothe
Illustration: Richard Carstensen
Revised and reprinted 1994
