Beautiful but Greedy Mute Swans Crowding Out Their Native Cousins

The swan, full-grown by then, still slept in their son’s bedroom. The Gibsons began to wonder, as fall leaves glided down the Miles River behind their house, if the long-necked beauty would ever join the others.

“Cyggie would do fine in the wild,” said Linda Gibson, one of many people who feed a growing flock of mute swans that live in this shallow, marshy section of Chesapeake Bay. “It’s ideal swan habitat out there.”

Too ideal, as it turns out. The exquisitely lovely mute swan--symbol of romantic destiny, beloved hero of fairy tales--is fast earning a reputation among North American wildlife biologists as a habitat-hogging cygnet machine.

The issue, the scientists say, is how to control burgeoning flocks without riling a public that is attached to the mute’s arched wings, gracefully curved neck and venerable history as the bird of European royalty.

The outsize, fiercely territorial immigrant from Northern Europe and Asia monopolizes the same limited habitat needed by the less elegant, native tundra swan and an array of other water birds.

The much smaller tundra, formerly known as the whistling swan for the sound its wings make in flight, migrates between arctic and temperate regions of North America. So does its larger cousin, the trumpeter swan, which winters in the interior West. Both species have been the object of extensive efforts to restore flocks that were nearly wiped out by hunters during the 19th Century.

Victorian-era Americans imported mutes to grace estate ponds and city parks. In recent decades, rapidly reproducing descendants of these birds have begun to take over the wetlands used by tundras, especially from Michigan to the East Coast. An estimated 12,000 wild mutes live in the eastern flyway.

Greediness is the mute swan’s hallmark. Unlike other birds, mutes won’t share nesting territory with different species. A pair, tenderly herding its brood with soft honks, can transform instantly into a hissing, wing-furling duo of torpedoes. Anything larger than a sparrow quickly learns to steer clear of a territory as large as 25 acres. The powerful swans have been known to kill dogs and even attack humans.

Crabs, fish and other birds that feed on submerged vegetation lose out to the mute’s voracious appetite. The 25- to 35-pound bird doesn’t just graze marsh grass; it wolfs down 8 to 10 pounds a day, ripping the plants out by the roots. Because mutes don’t migrate, marsh beds don’t have a chance to recover.

“What’s left for waterfowl that come for only a few months? Mutes are destroying habitat,” said Lucretia Krantz, associate director of the Wildfowl Trust of North America, based in Grasonville, Md.

The Chesapeake mutes number only an estimated 2,000, but scientists already link them to troublesome changes in the fragile bay’s ecosystem.

Where mutes have moved in, black ducks have disappeared. In the upper bay, rare terns and skimmers are dwindling because their tiny, ground-level nests are trampled by lead-footed mutes that congregate to molt on the birds’ breeding islands.

Recently half of the estuary’s painstakingly restored population of 40,000 tundra swans began passing up the Chesapeake entirely to winter in North Carolina, where so far there are no mutes.

The real concern, though, is not so much what already has happened as what could happen if the mute is allowed to continue reproducing at its current explosive rate.

The Chesapeake’s mute population descended from only nine birds that escaped from a private preserve in the mid-1960s, a 220-fold increase. That rate extrapolates in another 30 years to nearly 450,000, almost half the number of all waterfowl that now winter on the bay.

“The potential for reproduction is out of control,” said Doug Forsell, a wildlife biologist with the U.S. Fish and Wildlife Service’s bay field office. “The mute is a varmint species that we’re going to have to spend a lot of money controlling.”

Federal law doesn’t apply to mutes, a non-native species, so states may deal with them as they see fit. At least six states on the eastern flyway have control programs, although their approaches vary, usually according to regulations that existed before mutes became a problem. The neighboring Chesapeake Bay states of Virginia and Maryland illustrate the point.

Virginia, which allows limited hunting of tundra swans, has few mutes. “Mutes that wander down there probably get shot during hunting season,” Forsell said. “We’re glad someone’s keeping them from spreading to Virginia.”

Under an old law aimed at protecting native tundras that was enacted before mute swans appeared, Maryland prohibits killing swans of any species. So far, the state’s mute-control program has been limited to destroying eggs, an expensive and often unsuccessful approach.

Officials in the Maryland Department of Natural Resources want authority to cull mutes. But, fearing a no-win confrontation with animal-rights activists, they haven’t asked for it. The officials hope to build public support through a televised video that explains the problems mutes create for native wildlife.

But winning over mute-lovers like Linda Gibson promises to be a tough sell.

“I know real bird people don’t like mute swans, but they don’t hurt anybody,” said Gibson, whose family goes through 100 to 200 pounds of corn a week feeding mutes.

Cyggie, the young swan adopted by the Gibsons, finally flew their coop before Christmas, when he took up with a young swan with a broken wing. But he keeps in touch.

“Cyggie still knows us. When we call, he turns his head our way and talks to us,” Gibson said. She would like to see him choose a mate. “It sure would be fun to have some more little cygnets running around here.”