Denizens of rocky, turbulent waters, harlequin ducks are nimble swimmers and divers par excellence. Still, one oil spill could transform this tenacious little bird into a sitting duck.
By Frank Graham Jr.
I felt a familiar tingle of pleasure as I watched a raft of small ducks surrender to the sea's undertow. For a few moments they seemed helpless on the incline of water sweeping them into the gullet of an oncoming wave. The wave crashed, the surface boiled, and the ducks disappeared--only to bob back to the surface to ride on the subsiding foam like a flotilla of jaunty toy boats.
Long an admirer of the falcon's stoop, of its mastery of the air, I have come to recognize harlequin ducks as the avian wizards of our continent's wild water. Look for them in winter in the turbulent surf that breaks over the submerged ledges off northern islands and icy coastlines. In summer watch them pursue their tiny invertebrate prey through boulder-strewn rapids in fast-running streams. It's no wonder that a 19th-century taxidermist detected more mended broken bones in harlequins than in any other birds he had ever examined.
"They're often in the lee of ledges where the waves break, because that's good habitat for their prey," Glen Mittelhauser said one late-winter morning as we stood on the rocks at Isle au Haut, off the Maine coast. "The amphipods and other critters they eat favor these very rough areas, where oxygen is high and the surf stirs up nutrients for them."
Mittelhauser, a graduate student in zoology at the University of Maine, has followed these diving ducks in sleet and snow, rain and bitter cold for more than a decade. Harlequins are still reasonably abundant (although probably declining) in the northern Pacific Ocean, but little was known about the much smaller, genetically distinct Atlantic populations when Mittelhauser began studying them in the 1980s. What was known was that their numbers had fallen from a late-18th-century high of perhaps 10,000 birds to a population of fewer than 1,800. Eastern harlequins breed here and there along Canada's coast, from Labrador, Newfoundland, and Quebec south to northern New Brunswick. Most of the ducks from the southern part of that range winter in Maine.
"In 1988 there were about 250 harlequins wintering off the south end of Isle au Haut," Mittelhauser told me. "Canada put them on its endangered-species list in 1990, and hunting them was banned in the eastern part of the United States at about the same time. A year later we found only 140 birds wintering at Isle au Haut, but after that things turned around. The harlies are back to 250 again, and they may be increasing."
Few other North American bird species appear under so many different vernacular names: "lords and ladies" and "painted ducks," from their elegant carriage and plumage; "squeakers," "squealers," and "sea mice," from their rodentlike cries; "rock ducks," from their winter foraging places; and "torrent ducks," from their summer habitat. But the old-time ornithologists were undoubtedly sexist, and the names that stuck to dimorphic species generally described the male. The harlequin drake's coat of many colors was thought to resemble the parti-colored costumes of zany characters in Renaissance comedies. Despite the white patches on her head, the hen's brownish plumage offers maximum concealment while she sits on the nest.
Recent surveys have revealed three distinct Atlantic populations. One population breeds in Labrador and winters in Greenland, while the rest of the Canadian breeders winter on the North American coast, chiefly from the southern Maritime Provinces through Maine, Massachusetts, and Rhode Island to Maryland. Rarely, they are seen off Cape Hatteras and the Florida coast, and there is even a recorded sighting in Texas. The third population breeds and winters in Iceland.
The look-alike but genetically distinct western population may number 200,000 individuals, ranging from 500 to 600 summer breeders in the Rocky Mountains to an estimated 170,000 wintering in the Aleutians. Although the research is still scanty, and ornithologists no longer separate eastern and western harlequins into subspecies, there are behavioral differences. For instance, some western harlequins don't live up to their species' reputation for toughness, eschewing wave-battered coastlines for the more placid setting provided by shallow water over eelgrass and kelp beds. Long-term studies by biologists such as Glen Mittelhauser may uncover more subtle differences.
"For the most part, males outnumber females among sea ducks, and that's true of western harlequins," Mittelhauser said. "Perhaps females sitting on the nest are at greater risk. But in the East the difference isn't always significant, and for a long while I was actually seeing more females than males in Maine. I think that was a result of a strong hunting bias--harlequins were never a favorite target, except among hunters who wanted the beautifully patterned males as trophies. Males and females are about equal now."
The place to see harlequins, even back in the 19th century, has always been Isle au Haut, a six-mile-long, heavily forested granite island off Stonington, Maine. (Nearly a third of the island is included in Acadia National Park.) In 1896 Arthur H. Norton, a naturalist and later the Audubon Society agent in Maine, first described the island's harlequin ducks in The Auk, the quarterly journal of the American Ornithologists' Union, and he continued to study them for many years.
"While watching a flock playing in the breakers near us, we heard a conversational note, que-que-que, very much like the peep of young domestic ducks," he recorded in his notebook in 1938. "The harlequins locally were called squeakers--a voice name. The birds resorted with much regularity to particular chasms in the surf-washed shores; these chasms being locally called guzzles, from the guzzling sound of water surging in and out of them. Squeaker Guzzle is a geographical name at several outer islands, and Isle au Haut has its Squeaker Cove on its southern shoreline."
Mittelhauser, a dark-bearded young man, got to know the island in 1984, when he went to the College of the Atlantic (COA) in Bar Harbor, Maine, to study whales. There he quickly fell under the spell of William H. Drury Jr., an ornithologist and much-admired teacher, and "got sidetracked" to birds.
"In winter I spent a lot of time watching harlequins," Mittelhauser recalled. "There's a little cabin on Isle au Haut I liked so much I wanted an excuse to spend time there. After I graduated from COA I was able to find small grants from various public and private sources and keep coming back to the island--and the cabin--to study harlequins."
Then, in 1997, he began work on his master's degree at the University of Maine, supported, in part, by a grant from the National Park Service. His subject, naturally, is the harlequin duck. Mittelhauser is positioned to make a genuine contribution to the duck's natural history and conservation, partly because of his winter perch on Isle au Haut and partly because of the bird's unique characteristics: Not only do harlequins usually mate for life, they are also especially site-tenacious. They tend to return year after year to both their breeding and wintering places.
"We've learned a lot from banding them," Mittelhauser said as we watched a raft of 50 or more of the ducks bob in the surf in Merchant Cove, long a harlequin gathering place on Isle au Haut's snow-blanketed southern shore. "They can be caught in mist nets stretched across the streams where they breed. For a long while, though, researchers thought there was no practical way to catch them in winter. But even here, the harlies' behavior is so predictable that we found we could set up floating wooden platforms, stretch nets between them, and anchor them along certain stretches of shoreline where the ducks pass like clockwork."
Mittelhauser and his helpers have already placed white bands, each with a simple black letter and number (A4, H6, and so forth), on the legs of more than 300 ducks. This tells observers where the duck has been. When the air temperature rises above that of the water, harlequins regularly take a respite from the sea's pounding by resting on inshore ledges or rocks. An observer can approach these reasonably tame ducks with a spotting scope to read the numbers and letters. It's an exciting moment for Mittelhauser on Isle au Haut when he spots a bird banded elsewhere.
"A blue band with white letters means the duck was banded in Quebec," he said. "A yellow band with black letters comes from Labrador-Newfoundland. You really get a sense of how small the total eastern population is when you see the exchange of banding information with Canada. As soon as we started banding here, they began seeing our bands in Canada."
Banding has not only proved the site tenacity of these ducks, it has also established the bond between couples. Harlequins pair on wintering grounds, then fly north together. They build their nest close to a running stream, on a small midstream island, on high ground safe from flooding, or sometimes in a tree cavity. They feed in the rough current, diving and even walking like dippers on the stream bottom, competing with fish for the larvae of blackflies, stone flies, and other freshwater insects.
Once incubation begins, the male drops out. He flies to a familiar molting site and schmoozes with other males until his fresh plumage is in place. Then it's off to the south again, where he meets his mate on their designated wintering grounds.
"It's like a tradition," Mittelhauser said. "They keep coming back to places like Isle au Haut. You can find more than half of the Atlantic Coast wintering harlequins in Maine, well over 800 birds, in a 15- to 20-mile stretch among the islands in Penobscot and Jericho bays. It's funny, because there are some places you'd think are perfect harlequin habitat, but you never see them there."
He guesses that the female's devotion is to the site, and that the male's is to the female. And so Mittelhauser watches and worries chiefly about the ongoing health of this habitat. Although eagles and hawks take an occasional harlequin, and brooding females are often the victims of terrestrial predators such as weasels, predation is not much of a threat to the species. Nor is hunting, at the moment. Shooting pressure has never been great on the western species, and the law protects eastern populations. A more serious threat is habitat disturbance. Excessive logging in the West and the damming of streams for hydroelectric power in Atlantic Canada have eliminated many breeding sites. And then there is the omnipresent threat of oil in the sea.
"If a tanker hits a ledge along this stretch of Maine coast in winter," Mittelhauser said, "we could lose half the East's harlequins in one day."
He knows the toll taken by the Exxon Valdez in Alaska's Prince William Sound, where at least 3,000 oiled harlequins were found after the 1989 spill, and where, presumably, untold numbers went undiscovered. More than a decade later, the effects are still felt: Many harlequin hens in that area are smaller than those elsewhere, and they have a lower survival rate, though researchers haven't yet made a firm link with oil.
"A continuing threat to Atlantic harlequins is the way tankers keep pumping their bilges offshore," said Canadian research scientist Ian Goudie. "It's partly greed--tanker captains don't want to incur the charges for having their bilges pumped in port--and partly a lack of places to take the pumped oil. But we know that oil kills 100,000 seabirds off Canada every year, and it's getting worse."
So Glen Mittelhauser certainly has cause to worry. But on his side is the undoubted fact that he is monitoring one tough duck.
Frank Graham Jr. has written about birds for Audubon for more than 30 years. He lives on Maine's Narraguagus Bay, about 50 miles from Isle au Haut--as the duck flies.
Name: Harlequin duck (Histrionicus histrionicus)
Size: 16 to 18 inches long; weight varies during the year, averaging one to one and a half pounds.
Plumage: Male is slate blue with chestnut-brown sides and a variety of white stripes and spots. Female is better camouflaged: brown with a white belly and three white spots on each side of the head.
Range: North Atlantic from Greenland and Iceland to eastern Canada and, in winter, south along the coast to the mid-Atlantic states. In the Pacific, northeast Asia and Alaskan coast, south to California.
Call: High-pitched squeak.
Nest: Usually close to an inland stream, on the ground or a low cliff.
Food: Aquatic insects on breeding grounds; small amphipods, isopods, mollusks, and bivalves on the seacoast in winter.
© 2001 NASI
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