ONCE HUNTED IN VAST NUMBERS, THE OL' BLACK DUCK IS NOW IN JEOPARDY

From a tower overlooking three pairs of small artificial ponds in Laurel, Md., biologists study the feeding behavior of six duck broods, meticulously noting the birds' every move. Farther north, in Nova Scotia, a Canadian biologist keeps watch on the growth rate of ducklings on remote, nutrient-poor ponds and compares it with that of similar birds feeding in richer farm ponds and sewage treatment outlets. Elsewhere, a licensed trapper in the Maritimes lifts a huge, dark adult duck from a trap and removes the timeworn band from its leg, replacing it with a new one and mailing the old band to Washington, D.C. On a tidal marsh in New Jersey, a hunter picks up a duck he's just shot over his decoy rig, examines its feet and bill, clips a wing and stuffs it in an envelope. Then with a sigh he pulls in his decoys. Although the sky is full of ducks just waiting to toll into his blind, for him it must be another one-duck day.

All this activity—even the duck hunter's act of reluctant restraint—is in behalf of the black duck. Until recently, this big, shy, dark-feathered waterfowl with its coral-red legs and olive-green bill was the Crown Prince of the Atlantic Flyway, ranking second only to the Canada goose in the esteem of hunters along the East Coast from Cape Breton Island .to the Carolinas. There has always been something mysterious, almost magical, about "blackie." It is a bird of the dim hours, conducting much of its business in the gray half-light of dawn and dusk, often announcing its arrival over a blind with nothing more than the rip of powerful wings through the cold, dark air. To those who love it (and love to kill it), the black duck is at one with the boom of Atlantic surf on the nearby barrier islands, with the first pink touch of sunrise igniting the tips of the spartina grass, with the tang of salt and the dark iodine reek of marsh muck on patched but leaky waders.

From the sandy barrier beaches of Assawaman Island, on the Eastern Shore of Virginia, one can look north at sunset to the gantries and' blockhouses of NASA's rocket-launch range at Wallops Island, looming pale and misshapen in the pink light, an eerie echo of a turn-of-the-century Thomas Eakins painting. It is here that the black duck is making its last stand.

Cautious as a banker, a flock circles the decoys endlessly, remaining just out of range, checking the "blocks" from every angle. The slightest tag of weed fluttering underwater on a tide-swept anchor line will send it banking and whirling away, not to return that day, if ever. When the birds do pitch in, it's always at the edge of the decoy rig, and if a gunner rises to shoot before they have all committed themselves, they will be up and off again as if powered by retro-rockets. The black duck takes a lot of killing, but to thousands of waterfowlers since the days of the Pilgrims, it has been well worth it, especially when served up quick-roasted and blood-rare, with a pinch or two of sage and rosemary.

But now the black duck is in deep, perhaps irreversible, trouble. A generation ago hunters killed a million blackies a year along the Atlantic and Mississippi flyways (the birds occur only rarely farther west). Today it is estimated that there may be no more than a million and a half left in the world. Both the mallard and the wood duck now rank above the black in numbers taken by hunters each year along the Atlantic Flyway. Ironically, early in this century the wood duck was itself on the verge of extinction, and only a monumental effort by wildlife experts and duck hunters, aided by the return of farmland to a more natural state, brought it back to huntable levels. But skeptics fear that no such turnaround is likely for the beleaguered black. The species Anas rubripes, they say, is being hybridized out of existence.

The villain in this tale is the mallard, Anas platyrhynchos, that familiar green-headed paddler of every wet habitat from prairie potholes to city park ponds and suburban swimming pools. Some ornithologists theorize that the black duck species began breaking away genetically from the ancestral mallard some four million years ago. What evolved was a bird that resembled the hen mallard, but with a much darker color and a pronounced predilection for forest-country beaver ponds and East Coast salt marshes as its breeding and wintering zones. The mallard, in those days at least, preferred more open country—the pothole ponds of the Midwestern prairies. Some biologists believe that along the way the emerging black duck developed an immunity to a blood parasite called a leucocytozoan, which is transmitted by the blackflies that make the summer woodlands of New England and eastern Canada—the blackie's prime grounds—a living, biting, scratching, swatting hell for Homo sapiens.

All was well and good between the two species as long as they remained separate. But then, shortly after World War II, the population dynamics of the birds began to change. Black duck numbers began a sharp decline even as mallards thrived and spread. One of the major indicators the U.S. Fish and Wildlife Service employs to keep track of the shifts in duck population is the "mid-winter survey." which tots up the number of ducks found on the species' wintering grounds. The 1955 winter survey showed 760,900 blacks on the water between Canada and the Carolinas, and inland to the lower Midwest. By 1960 the winter count had dropped to roughly half a million, and in January '83 researchers could spot only 293,800.

Some 60% of this decline took place during the 1950s and early '60s. The sharp drop, amounting to more than 5% of the total black duck mid-winter survey figures in some years, coincided with the infamous postwar era of swamp-filling, when every bog, mire, swale, slough, marsh and fen within reach of a bulldozer was considered worthless if not downright evil. The swamps were filled to make room for housing developments, industrial parks, shopping centers and increased agricultural acreage.

At the same time, the swamps that weren't filled were slathered with DDT to eliminate nasty bugs, mainly mosquitoes. The pesticides, working their way through the food chain, caused eggshell thinning among many birds, most notably the big raptors at the top of the chain—bald eagles, peregrine falcons and ospreys. "In retrospect," says Dr. Robert Smith of the Fish and Wildlife Service's Office of Migratory Bird Management, "an eggshell-thinning problem may have occurred among black ducks, too, but we weren't looking for it so we didn't see it. Eagles and peregrines have come back strongly since the DDT ban in the early 1970s, so there's no reason to think it's still a problem with blacks. Still, we're continuing to lose 1.5 to 2 percent of the population each year."

Nonetheless, the double-barreled blast—swamp destruction and pesticides—sent the black duck reeling into a downward population spiral. Simultaneously, its cousin the mallard was expanding its range and, more important, adjusting to the proximity of people. Mallards will eat nearly anything, and they are as much at home in New York City's Central Park as on a wild marsh, scarfing hot-dog buns or sludge worms with equal rapacity.

As the mallards invaded what was once black duck territory, the two closely related species began mating—and producing fertile offspring, an indication that the species difference was not all that great. This "swamping" of the black duck gene pool was abetted, with all the goodwill in the world, by many conservation groups and some states, which released pen-raised mallards into the wild along the flyways. During the past decade, Maryland alone released about 15,000 mallards a year, a program mandated by law. This despite the fact that the state's winter survey of blacks had plummeted from 149,000 in 1956 to a scant 16,900 this year.

Collections of wings from birds killed by hunters have shown that as many as 15% of the so-called mallards and blacks being shot were actually hybrids. Experienced waterfowlers can tell the hybrids at a glance: There is a mallard-like green sheen to the drake's head feathers, and the bright red feet from which the blackie derives it specific epithet (rubripes is Latin for "red foot") are often a rather sickly orangish yellow. But the 15% figure may be a low estimate, at least on some stretches of the Atlantic Flyway. Though mallards have declined by 28% since the 1960s at the southern end of that flyway, they are up 94% in New England, 29% in Maryland and Virginia and a whopping 115% along the New York-New Jersey shore and in Pennsylvania.

"The mallards are thriving in areas that were classic black duck wintering grounds," says Smith. "These mallards are prairie ducks bred up in Ontario and Quebec, coming down the Atlantic Flyway to winter over where they rarely were seen before. It's not surprising that the biggest increase has been in New Jersey. The Jersey marshes have held their quality much better than the Chesapeake, which collects detritus flowing down the Delaware River system."

Kill figures underscore the population change. In the 1970s, New England hunters killed twice as many blacks as mallards. Now, the kill figures are about even in what is one of blackie's last strongholds south of the Canadian border. In New York, New Jersey and Pennsylvania, hunters in 1983 killed 200,000 mallards to 63,000 blacks. In Delaware, Maryland, Virginia and West Virginia, 114,000 mallards were shot versus 32,000 blacks, while in North Carolina, South Carolina, Georgia and Florida, the numbers were 90,000 mallards, 18,000 blacks. Biologists say kill figures may approximate a quarter of the total population of any duck species. Thus, there may be about 1.6 million mallards currently using the former black duck range for various purposes, including mating. Last spring conservation writer George Reiger observed a mallard drake courting lustily at least two black duck hens on his pond near Locustville, Va. As Reiger explains, pair-bonds among ducks are established during the winter, long before the birds move north to their breeding grounds. If a mallard drake pairs with a black duck hen somewhere down in Virginia, he will follow her to the Northeast. There he will be exposed to a wealth of mating opportunities with other black hens. The danger here, as many biologists see it, is that the resultant offspring of a black duck-mallard cross could lose the genetic immunity to leucocytozoan infestation peculiar to the black. If so, many of the young would not survive the blackfly country to wing south as juveniles in the fall. This loss could account for some of the slow, steady 1.5% to 2% decline in black duck numbers cited by Smith.

"But I know of no study that shows the crosses losing immunity," Smith says. "Indeed, perhaps we're seeing the creation of a superhybrid. A kind of 'hymallard' that's as likely to be found on a lonely backcountry beaver pond as on the Reflecting Pool of the Washington Monument."

Watermen on the Eastern Shore speak with awe of a "giant" race of black ducks they sometimes see—huge, bright-footed birds nearly the size of geese—and it has long been believed that there is indeed a "maritime" race of the birds that rarely ventures far south of its home range in Labrador. Yet Smith feels that size is merely an indicator of age among black ducks. A licensed Canadian duck trapper for years has been sending Smith bands taken from outsized black ducks he's caught and released. The bands are timeworn to near illegibility, proving that the big birds are also old birds. "The biggest black duck I ever shot," Smith says, "was on a river in Tennessee. It's unlikely he flew there from Labrador."

Another possible cause of the ongoing black duck decline might well be acid rain. The bird's Northeast breeding grounds are directly in the path of weather systems carrying sulphur dioxide from the smokestacks of the industrial Midwest. Just as hundreds of high-country lakes in the Adirondacks and Vermont's Green Mountains have found their pH levels plummeting to the acid end of the scale, and consequent lifeless-ness, so too have many ponds and lakes in Maine and the Maritimes. Though acid rain by itself would not kill the black ducks, it could kill off enough of the food in the ponds where their broods mature to slow growth and cause weakness, even starvation.

At the same time, down in Laurel, Mike Haramis, a waterfowl biologist at the Patuxent Wildlife Research Center, is conducting an experiment that shows the effect of acid rain on 10-to-20-day-old black ducks. Last spring Haramis and some colleagues raised six separate broods of black ducks on three pairs of different man-made ponds. The ponds, which are 40 feet in diameter and a maximum of 2½ feet deep, are bottomed in 10 inches of topsoil over plastic, and have antipredator nets rigged overhead "to keep out the owls." One pond in each pair is maintained at a highly acid pH of 5, the other at an essentially neutral pH of 7. The young ducklings eat animal matter during their first few weeks of life, snapping up nymphs and other larvae that swim in their natal waters. Of a dozen young birds raised on a nonacid pond, 10 gained weight and two maintained their weight. Of the birds raised on an acid pond, three maintained their weight, six lost weight and three died.

What's more, as Haramis points out, the ducklings in the "stressed" environment, i.e., the acid pond, were more likely than their better-fed relatives to go off on their own in search of food, thus abandoning the security against predators that comes with flock behavior, or what biologists call "brood integrity." "They're also much less selective in what they'll eat," he says. "I've seen them ingest mud and other nonorganic material that does them no nutritional good. You'll see them truckin' through the uplands, eating grass, or off alone by themselves in the deep woods." In short, translated to a natural scene, easy pickin's for a sharp-eyed hawk, fox, coyote or owl.

It may well be that the black duck's drift toward extinction is the result of what biologists call a synergistic process—a combination of adverse factors working together to achieve an end that no single one could accomplish. Loss of habitat and the widespread use of pesticides 30 years ago may have triggered the decline, and while subsequent legislation to protect the wetlands and the ban on DDT in 1972 were attempts to halt those processes, the worst damage had already been done.

In 1981, the Black Duck Subcommittee of the Atlantic Flyway Council issued "A Management Plan for the Black Duck," which called for a 25% reduction in bag limits for the species, beginning in the 1982-83 season. The U.S. Fish and Wildlife Service, which sets regulations for migratory birds, was reluctant to do so. Fully 85% of the blackies that use American waters originate from Canadian breeding grounds, and the Feds knew that Canada was not yet ready to reduce its own black duck harvest. Then in September 1982 the Maine Audubon Society and the Humane Society of the United States brought suit against the Fish and Wildlife Service, seeking an injunction to close the black duck season entirely that fall and winter. Ironically, the plaintiffs used the Service's own data to demonstrate the seriousness of the black duck problem. But the U.S. District Court in Washington, D.C. ruled that the Service was living up to the terms of the Migratory Bird Treaty Act of 1918 and was acting in the best interests of what it termed "the resources." Not until the 1983-84 season did the Service reduce black duck limits, promulgating "split seasons" in much of the Atlantic Flyway, timing them so that hunters could not shoot blackies during their greatest abundance on the flyway, and then could take only two birds a day. In other parts of the black duck's range, the limit was one a day through a 50-day season. The same regulations applied this past season.

For 1983-84, the Canadian Wildlife Service retained its bag limit of six birds a day; this past season it went along with the American reduction plan. But the Canadian plan is structured differently. In the eastern provinces, hunters can take four blackies a day, but farther west in parts of Quebec, where the birds are rarer, two is the limit, and in southern Ontario the limit is one.

Though at best it's a stopgap, the reduction of hunting pressure is particularly important in the black duck equation because of the bird's peculiar vulnerability to the gun. Kill figures from 1982 show that about 36% of the total hunting deaths among blackies are of immature hens. By contrast, only 24% of the mallards killed each year are juvenile hens. Since the mallard drake is so conspicuous with his green head, auburn breast and white flanks, he is the preferred target of mallard hunters. Male and female blacks look alike on the wing, but the females are more trusting and fall easier victims to a good decoy layout. Juvenile black ducks of both sexes, naive in the ways of the duck blind, are 1½ times more apt to be shot than adults.

Adult or juvenile, the black duck is by its very nature especially prone to illegal hunting. Every outlaw gunner knows that Ol' Blackie does most of his traveling in the dim hours of dusk, and shooting is legal only between sunup and sundown. A clever rig of decoys, spiced by the judicious but illegal addition of a handful of corn kernels (which ducks can see on the mucky marsh bottom from incredible altitudes), can toll in dozens of birds to the shotgun. But until recent years most illegally taken black ducks were captured in traps rather than shot.

One of the best spots for a trap is a pond in the middle of a marsh. Stakes are driven into the hard sand at the pond's edge, and a strong net rigged over them. Each trapper has his own special trapdoor setup, and the pond is baited with corn, sometimes for weeks, before the ducks are captured. The ducks get addicted to the high-energy corn diet and the pond becomes a way station on the daily feeding tour. At high tide, on a good night a trapper can take 30 or 40 ducks, and one outlaw claimed to have caught 499 in a single midnight round of his traps. Jim Williams, a legendary warden of the last generation, destroyed more than 15,000 duck traps during the course of his career, with a high of 496 in one week and, working alone, 78 in a single night's outing. His efforts saved more than 500,000 ducks, many of them blacks.

But that was in the old days, the likes of which may never be seen again. Over the past decade, federal and state efforts to enforce waterfowl regulations have been focused on the goose fields of the Atlantic Flyway. But the Canada goose is thriving as never before—indeed, it's a "pest" in some areas, especially on golf courses, where nesting geese chase golfers who stray into the rough. Perhaps it's time for the regulators to shift their attention back to ducks—especially the beleaguered blackie. Combined with the laudable reduction in hunters' bag limits and the inspired research of so many wildlife scientists, increased enforcement might be part of a new synergism that could bring the bird back from the brink of disaster. An Atlantic Flyway without the wily black would be a disaster area for sure.