The Bizarre Life of the Harlequin Duck
Biologists are still baffled by a duck that would rather swim than fly and that migrates east and west instead of north and south
A gentle splash on the water's surface punctuates the landing of a harlequin duck on a secluded mountain stream. Moments later, her mate touches down. They have traveled far to reach this spot, along the way perplexing a cadre of biologists eager to unravel the enigmas surrounding this most mysterious of American waterfowl.
Harlequins are sea ducks that live in the mountains. They migrate east and west instead of north and south like other ducks. And they prefer roaring alpine streams to the quiet marshes favored by other waterfowl. "I can't imagine why this bizarre lifestyle might have evolved," says Greg Schirato, a wildlife biologist with the Washington Department of Fish and Wildlife. "It just doesn't make any sense."
Schirato and other scientists are working hard, however, to solve the harlequin mysteries. Recent research has revealed that these birds reproduce slowly, are vulnerable to oil spills and become quite attached to certain streams--and to each other. Banding studies have documented the ducks' extensive travels--some harlequins winter along the British Columbia coast and nest in the Rocky Mountains. "But lots of pieces to the harlequin puzzle are still missing," says Frances Cassirer, wildlife biologist with the Idaho Department of Fish and Game.
As biologists learn more about harlequins, concern about the bird grows. While many of North America's 35 duck species prosper, harlequin numbers appear to be declining. In 1990, Canada's Committee on the Status of Endangered Wildlife designated the harlequin as endangered in eastern Canada, and in 1991 the species became a candidate for U.S. listing. Only one North American duck, the spectacled eider, is probably more imperiled than the harlequin.
This continent is home to two widely separated harlequin populations. A small eastern contingent breeds in maritime Canada and winters on the New England coast. The more numerous Pacific harlequins winter along coastlines from the Aleutians south to California and breed in western mountain ranges as far inland as Wyoming. Additional harlequin populations also exist in Greenland and Iceland.
"Judging from their current distribution and the much larger population in the North Pacific, it's possible that harlequins evolved in the West and have been slowly colonizing eastward," says Pete Clarkson, a park warden working with harlequins in Canada's Jasper National Park. This hypothesis suggests that huge gaps subsequently developed in the bird's distribution, creating the now isolated groups. Puzzled by the disjunct distribution, researchers have begun studying harlequin DNA to see how closely the different populations are related.
East Coast harlequin numbers have declined from perhaps 10,000 birds in the 1800s to fewer than 1,000 currently. "This population is doing terribly and may be headed for oblivion," says Jim Reichel, a zoologist with the Montana Natural Heritage Program. Before its prohibition in 1989, sport hunting was probably the main mortality factor for eastern harlequins. Now, oil spills and dams are the primary problems.
Early, unreliable estimates for the Pacific population went as high as a million birds. Today, biologists guess there may be about 250,000. "The little data we have," says Reichel, "suggest that western harlequin numbers have declined over the last 40 or 50 years." Habitat loss, oil spills and disturbance of nesting ducks by humans are thought to be the principal culprits.
The decline has researchers scrambling to get a better fix on the bird's status--and its unusual lifestyle. Every spring and summer, researchers band harlequins to identify migration routes and habitat preferences. In addition, biologists monitor streams to plot harlequin distribution and to gauge the species' tolerance for disturbance. Researchers also attach radio transmitters to hens to locate nests.
Weighing only a pound and a half, a harlequin is barely half the size of a wild mallard. The hen is cloaked in subdued browns, but the drake's splashy colors--seemingly assembled by a committee of first graders--are among the showiest in the waterfowl world.
Although classified as sea ducks, these avian mariners weigh anchor each spring and migrate inland to breed. The Pacific birds wend their way to rushing, tumbling mountain streams, while the eastern birds settle on turbulent rivers primarily in Quebec and Labrador but occasionally in Newfoundland. The Pacific harlequin is the only duck in the world that divides its time between sea and mountains.
In spring, breeding-age western harlequins--those two years and older--leave Pacific coastal waters for mountain streams in Alaska, Washington, Oregon, Montana, Idaho, Wyoming, Alberta, British Columbia, the Yukon and the Northwest Territories. A few even cross the Continental Divide to nest. Researchers believe some harlequins journey from sea to summit as anadromous fish do--by following streams.
Harlequin society is matriarchal, with adult females returning salmonlike to their natal streams to reproduce. "While on the coast, a young female picks out a bachelor to take home," says John Ashley, a wildlife biologist at Glacier National Park. Because nesting females are more vulnerable to predation than are males, plenty of unpaired males also show up on the mating grounds, although they rarely get a chance to breed.
A harlequin pair may remain together for years, apparently with great loyalty. In 1992 on Washington's Morse Creek, Schirato and fellow Department of Fish and Wildlife biologist Matt Nixon captured a female in a banding net, but her mate escaped downstream. Seeing his partner detained, the male returned to the net, repeatedly called to her and eventually became entangled himself. "I've never seen other ducks do that," says Schirato.
In May or June, the female lays about six eggs in a nest expertly concealed in streamside vegetation, a hollow tree or logjam. The male now returns to the ocean, precluding any possibility of renesting if the eggs are destroyed. Oddly, some unpaired females choose this late time to migrate inland. "It's possible," says Ashley, "that these females might pass the ocean-bound males headed in the opposite direction." The tardy females, which are young birds looking for future nest sites, do not mate.
With luck, a mated hen will produce a few new harlequins. "Generally, harlequin reproduction is rather abysmal," says Reichel. "They don't breed until they're two years of age or older, they lay relatively few eggs, and they can't renest if they lose their clutch."
Mink, goshawks and other predators likely kill some ducklings, but probably a greater proportion of harlequin young fall victim to cold weather or high water. Raging streams do not bother the adults, however, thanks to swimming skills that sometimes seem almost fishlike. For them, no torrent is too turbulent. "Harlequins routinely navigate rapids--with water spraying and foam flying--that few kayakers would ever enter," says Ashley.
The duck even feeds in the seething current, diving to force its way to the stream bottom. With wings held tight against its body and feet pumping rearward like propellers, the bird noses troutlike from rock to rock, searching for aquatic insects to eat. Meanwhile, the water churns around it. "It must be like swimming in a washing machine," says Ashley. After 20 or 30 seconds, the harlequin bobs to the surface for air, then dives again.
For adults, the swift current provides the best defense against most dangers. When threatened, a harlequin simply swims into the watery maelstrom and is swept downstream to safety. On the relatively rare occasions when stream-dwelling harlequins fly, they remain low and follow the stream's every twist and turn.
Practicing in quiet backwaters, young harlequins soon become adept at negotiating tricky currents. Before they learn to fly, however, their mother may return to the coast, leaving the youngsters to fend--and navigate--for themselves. "Some hormonal urge must tell the female to migrate now!" speculates Cassirer. "Fortunately, the young somehow know where to go when they later learn to fly." The prevailing theory holds that hens (and the males before them) must return to the coast before their annual molt renders them flightless.
By late September, virtually all harlequins are in coastal wintering areas, where they congregate in substantial flocks and feed in the nutrient-rich intertidal zone. Often, they forgo protected bays in favor of the roaring surf. Violent water, it seems, is in their blood.
Harlequins are at jeopardy on the coast, threatened primarily by oil spills and other pollution. In 1989, the Exxon Valdez disaster dumped 11 million gallons of oil into Alaska's Prince William Sound, killing or injuring thousands of harlequins. Since then, harlequin reproduction in the spill area has been virtually nil, with only three known broods produced between 1989 and 1993 in the most heavily oiled area. Even small amounts of oil can harm harlequins by getting in their food or by traveling from the adult feathers to the eggs, killing unhatched ducklings.
On inland streams, harlequins face other problems. In Washington (and perhaps elsewhere), poachers sometimes seek harlequin nests and capture live adults, which sell in Europe for as much as $5,000 per pair.
Various industrial activities--such as logging, mining and road building--that degrade water quality can drive harlequins away from habitat, at least temporarily. When a stream becomes silted, the aquatic insects upon which harlequins feed often drift downstream until they find clean water, a process that can put the insects out of the range of individual birds. Also, turbid water makes it difficult for the ducks to see the insects that do remain. "These two factors can have significant short-term impacts on harlequins," says Cassirer. "Any action that puts dirt in a stream can harm them." Biologists in the East more often cite hydroelectric development as the industrial activity most threatening to harlequin ducks.
Another problem for harlequins appears to come from boaters, fishermen and other recreationists who unintentionally disturb the birds. For example, in 1989, increased rafting and kayaking in Alberta's Jasper National Park began driving about 15 pairs of harlequins away from a prime stretch of the Maligne River. "It got so the ducks were being disturbed about every half hour, and eventually they abandoned the area," says Pete Clarkson. In 1993, human activity was banned on this stretch of the Maligne, and the harlequins have since returned. Park authorities have established a waterfowl viewing station on a bridge over the river, and every year thousands of people come to watch the ducks.
Harlequin hunting is still allowed in the West, though the birds are absent from most inland western states and provinces during all or most of the fall hunting season. But, says Cassirer, because of the small numbers of harlequins in many areas, even low levels of hunting on the coast could have an effect on inland breeding populations. "Many biologists are concerned about the fact that in the western Lower 48 and in Canada, bag limits and seasons for harlequin ducks are the same as those for mallards and other common species," Cassirer says. "When mallards are doing well, as they are this season, bag limits and seasons on all ducks, including harlequin ducks, increase." However, sufficient data are unavailable to determine accurately the impact of hunting on the population.
Although biologists don't like to speculate about the future of the Pacific harlequin population, they agree that this duck is swimming upstream. "Harlequins have it tough all the way around, from a cold, high-country breeding ground to a coastal wintering area that's often polluted," says Ashley. "Frankly, I don't know how they've lasted this long."
Gary Turbak lives in Missoula, Montana, only a short drive from harlequin country in Glacier National Park.