Speaking Of Swans
November 03, 2010
They are the largest waterfowl in the world--eight feet from wing tip to wing tip, five feet from bill to tail, white as new-fallen snow. They attract attention wherever they fly.
From a swan's point of view, at least, this notoriety hasn't always been comforting. For generations, swans were a coveted source of feathers and down. From 1853 through 1877, the Hudson's Bay Company bought more than 17,000 swanskins from native hunters in Canada, reselling the feathers to the makers of women's hats and fans in England and Europe.
By the 1930s, a century of persecution and habitat loss had taken its toll. North America's tundra swans had become scarce and wary, and the larger trumpeter swan, beset on its prairie nesting grounds as well as on migration, was near extinction.
The recovery of American swans is one of the great success stories in wildlife conservation. With effective protection, tundra swan populations bounced back quickly, reaching almost 50,000 birds by 1950 and about 170,000 today. The nation gave trumpeters their own refuge in southwestern Montana where winter feeding and intensive habitat management rescued the species. By 1954, estimates had risen past 600 birds; the last range-wide count, taken four years ago, found more than 23,000 trumpeters in three populations.
While our native swans were struggling through hard times, a third species of swan was making itself at home in the East and Midwest. The mute swan is a European native that was imported in the 19th and 20th centuries to decorate reflecting pools on country estates. With a talent for raising broods in urban areas, some of these domestic birds escaped and established wild populations from Massachusetts to New Jersey as well as in Michigan. They've done especially well in Chesapeake Bay where the population grew by more than 1,000 percent between 1986 and 2002. These days, biologists estimate that the Atlantic Flyway has more than 14,000 mute swans.
For anyone who cares about wildlife, the recovery of native swans is great news, but whether you're managing swans, snow geese or white-tailed deer, it's possible to have too much of a good thing. Hunting offers the most efficient way of responding to a burgeoning population of game animals, reducing numbers while it raises money for conservation. State and federal officials have opened tundra swan seasons in several states. In Maryland, biologists are trying to get permission to kill mute swans to avoid an ecological train wreck. Unfortunately, in this kinder, gentler age, wildlife management that involves any sort of killing nearly always bogs down in controversy.
In the West, the argument is fed by an overlap between two species of nearly identical native swans. The smaller tundra swan has tripled its population in the last 50 years, from an average of 35,000 birds in the 1950s to more than 84,000 in the last decade. Indices from the breeding grounds in Alaska and western Canada have reached as high as 216,000 in recent years. The larger trumpeter swan has staged an even more remarkable recovery, from about 100 birds in the early 1930s to around 4,000 birds in recent years.
With these increases came the inevitable difficulties. The number of young birds in the flocks has declined in recent years, suggesting poorer survival of cygnets on the breeding grounds. Disease has taken its toll down the flyway--between 1975 and 1981 biologists found nearly 7,000 tundra swans killed by avian cholera, and in California, more than 1,000 swans died of cholera in the winter of 1987-88. The cholera pathogen has now spread to migration staging areas in eastern Idaho and north-central Montana.
In 1962, Utah opened a limited tundra swan season. Swans became legal game in parts of Nevada in 1969, in Montana's share of the Pacific Flyway in 1970, and in Alaska in 1988. Because tundra swans and trumpeter swans are so similar, except in size, managers have examined the harvest carefully to keep track of the number of protected trumpeters lost to hunters. In the last nine years, hunters have taken more than 9,300 tundra swans in these three states--managers have found 42 trumpeters that were killed accidentally.
Objections to the western hunts surfaced in the mid-1990s. While both trumpeter and tundra swan numbers were on the rise, opponents worried that one flock of trumpeters was not prospering. Swan specialists call it the tri-state flock, a group of trumpeters which nests in the Yellowstone region of southwestern Montana, northwestern Wyoming and southeastern Idaho.
While this area was the last stronghold of trumpeter swans in the early 20th century, it doesn't offer the birds much except solitude. The growing season is short; the lower elevations get little precipitation, and the winters can be punishing. Not surprisingly, the tri-state swans have struggled. Since 1967, fall counts have never documented more than 600 birds. In the last five years, fall populations have averaged fewer than 400.
Perhaps the greatest problem facing these swans is a lack of winter habitat. In a severe winter, nearly all the birds gather on a stretch of Idaho's Snake River where warm springs keep the water open and a slow current allows a good crop of aquatic vegetation to grow. The local birds can clean up much of this food themselves, but they often share this stretch of river with hundreds of trumpeters from Montana and southern Canada. Die-offs aren't uncommon.
The chronic food shortage in Idaho would seem to be a perfect reason to migrate, but the tri-state swans don't. Some observers believe the long-term winter-feeding program at Red Rocks National Wildlife Refuge in southwestern Montana killed the migratory tradition in the flock, although there is no direct evidence that these birds ever migrated. Biologists have tried to encourage migration--they quit feeding at Red Rocks, hazed the birds off the refuge and other areas, and have even moved swans to other winter havens. In spite of these efforts, the swans cling to their traditional wintering grounds.
Opponents of the tundra swan hunt in Utah worry that any trumpeter migrating out of the tri-state area runs the risk of being killed farther south. The problem is more than the loss of a swan, in their view--they argue that discouraging migration out of the tri-state region means that this group of swans will probably continue to struggle. Several groups, including the Fund for Animals, have tried to stop the hunt and have even petitioned the U.S. Fish and Wildlife Service to place the tri-state flock on the federal list of threatened species. So far, they've failed.
Supporters of the hunt point to the ongoing growth of trumpeter swan numbers in the West, even after 40 years of tundra swan hunting. They worry that problems with disease and crop depredation will grow if the swan populations aren't controlled, and they point out that hunters have funded transplant programs that are re-establishing trumpeter swans in other parts of the West.
While the trumpeter controversy simmers in the West, the East faces a swan debate that is less complicated but just as intense. Five
captive mute swans escaped into the Chesapeake Bay in 1962. Today, the mute swan population on the bay has soared to almost 4,000. This population explosion is causing a host of problems. Mute swans are displacing native birds, including mallards, Canada geese, black skimmers and a variety of terns, including the endangered least tern. Biologists estimate that the swans are eating nine million pounds of aquatic vegetation a year, depriving crabs and sport fish of important food and cover. There is even reason to believe that the mute swans may be harassing native tundra swans on the bay--in the last 30 years, the population of tundra swans wintering in Maryland has dropped by 30 percent.
Over the last eight years, the Maryland Department of Natural Resources and several federal agencies have addled eggs in mute swan nests, transplanted adult swans, and, on occasion, killed problem birds. In 2003, the state applied to the U.S. Fish and Wildlife Service for permits that would allow them to kill 1,500 mute swans a year, but the Fund for Animals and several other parties sued to stop the process. At last report, a federal judge had issued a preliminary injunction against the permits.
While the biologists scramble to provide more information, the mute swans keep breeding-- at their current pace, the Chesapeake Bay population may reach 20,000 birds in the next decade. Once again, we find ourselves running an uncontrolled ecological experiment involving an entire landscape. We're sure to learn something from the exercise, but by the time we've gathered enough information to fully illuminate the situation, it may well be too late to reverse the effects.
In this age of information overload, Americans seem ever more inclined to make up their minds about complex subjects by leaning on symbols. The arguments surrounding these two questions of swan management offer hunters and biologists a look into the emotional issues that color public attitudes toward wildlife. Biological analysis can help us decide how things are, but it won't help us decide how we want them to be.